what is sql1

8/16/2019 What is SQL1

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What is SQL?

SQL is Structured Query Language, which is a computer language for storing, manipulatingand retrieving data stored in relational database. SQL is the standard language for RelationDatabase System. All relational database management systems like ySQL, S Access,!racle, Sybase, "nformi#, postgres and SQL Server use SQL as standard database language.

History:

•

1970 -- Dr. $dgar %. &'ed& (odd of ") is known as the father of relational databases.*e described a relational model for databases.

• 1974 -- Structured Query Language appeared.

• 1978 -- ") worked to develop (odd+s ideas and released a product named SystemR.

• 1986 -- ") developed the first prototype of relational database and standardi-ed by

AS". 'he first relational database was released by Relational Software and its laterbecoming !racle.

Advantages SQL?• Allows users to access data in relational database management systems.

• Allows users to describe the data.

• Allows users to define the data in database and manipulate that data.

• Allows to embed within other languages using SQL modules, libraries / pre0compilers.

• Allows users to create and drop databases and tables.

• Allows users to create view, stored procedure, functions in a database.

• Allows users to set permissions on tables, procedures, and views

SQL Proess! SQL Arhitet"re:

1hen you are e#ecuting an SQL command for any RD)S, the system determines the best

way to carry out your re2uest and SQL engine figures out how to interpret the task.

'here are various components included in the process. 'hese components are QueryDispatcher, !ptimi-ation $ngines, (lassic Query $ngine and SQL Query $ngine, etc. (lassic2uery engine handles all non0SQL 2ueries but SQL 2uery engine won+t handle logical files.

%ollowing is a simple diagram showing SQL Architecture3


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SQL #o$$ands:

'he standard SQL commands to interact with relational databases are (R$A'$, S$L$(',"S$R', 45DA'$, D$L$'$ and DR!5. 'hese commands can be classified into groups basedon their nature3

%%L - %ata %e&inition Lang"age:

Data Definition Language '%%L( is a standard &or o$$ands that define the di&&erent

str"t"res in a data)ase* %%L state$ents reate+ $odi&y+ and re$ove data)ase o),ets

s"h as ta)es+ inde.es+ and "sers* #o$$on %%L state$ents are #/A+ AL/+ and

%/2P*

#o$$and %esri3tion

(R$A'$ (reates a new table, a view of a table, or other ob6ect in database

AL'$R odifies an e#isting database ob6ect, such as a table.

DR!5 Deletes an entire table, a view of a table or other ob6ect in the database.

%L - %ata ani3"ation Lang"age:

A data manipulation language '%L( is a &a$iy o& synta. ee$ents si$iar to a o$3"ter

3rogra$$ing language "sed &or seeting+ inserting+ deeting and "3dating data in a

data)ase* Per&or$ing read-ony 5"eries o& data is so$eti$es aso onsidered a

o$3onent o& %L

#o$$and %esri3tion

S$L$(' Retrieves certain records from one or more tables

"S$R' (reates a record

45DA'$ odifies records

D$L$'$ Deletes records

%#L - %ata #ontro Lang"age:

A data control language '%#L( is a synta. si$iar to a o$3"ter

3rogra$$ing language "sed to control aess to data stored in a data)ase

'A"thoriation(* n 3arti"ar+ it is a o$3onent o& Str"t"red Q"ery Language 'SQL(*

.a$3es o& %#L o$$ands in"de: /A to ao s3ei&ied "sers to 3er&or$

s3ei&ied tas;s*

#o$$and %esri3tion


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7RA' 7ives a privilege to user

R$8!9$ 'akes back privileges granted from user

A ransation #ontro Lang"age :'(L; is a computer ang"age and a subset of SQL, usedto ontro transationa processing in a database. A transation is logical unit of work thatcomprises one or more SQL statements, usually a group of Data

anipulation Lang"age :DL; statements.

What is table?

The data in RDBMS is stored in database objects called tables. The table is a

collection of related data entries and it consists of columns and rows.

Remember, a table is the most common and simplest form of data storage in a

relational database. Following is the example of a !ST"M#RS table$

+----+----------+-----+-----------+----------+| ID | NAME | AGE | ADDRESS | SALARY |

+----+----------+-----+-----------+----------+

| 1 | Ramesh | 32 | Ahmedabad | 2000.00 |

| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

What is field?

#%er& table is bro'en up into smaller entities called fields. The fields in the

!ST"M#RS table consist of (D, )*M#, *+#, *DDR#SS and S**R-.

* field is a column in a table that is designed to maintain specific information

about e%er& record in the table.

What is record or row?

* record, also called a row of data, is each indi%idual entr& that exists in a table.

For example there are records in the abo%e !ST"M#RS table. Following is a

single row of data or record in the !ST"M#RS table$


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+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+

* record is a hori/ontal entit& in a table.

What is column?* column is a %ertical entit& in a table that contains all information associated with

a specific field in a table.

For example, a column in the !ST"M#RS table is *DDR#SS, which represents

location description and would consist of the following$

+-----------+

| ADDRESS |

+-----------+

| Ahmedabad |

| Delhi |

| K#$a |

| M"mbai |

| h#,al |

| M |

| Ind#)e |

+----+------+

SQL Syntax

S0 is followed b& uni1ue set of rules and guidelines called S&ntax. *ll the S0

statements start with an& of the 'e&words li'e S##T, ()S#RT, !2D*T#, D##T#,

*T#R, DR"2, R#*T#, !S#, S3"4 and all the statements end with a semicolon

567.

(mportant point to be noted is that S0 is case insensitive, which means S##T

and select ha%e same meaning in S0 statements

S0 S##T Statement$

SELE& #l"mn1 #l"mn2....#l"mnN

4R5M $able6name7


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S0 D(ST()T lause$

SELE& DISIN& #l"mn1 #l"mn2....#l"mnN

4R5M $able6name7

S0 43#R# lause$


4R5M $able6name

8(ERE &5NDII5N7

S0 *)D8"R lause$


4R5M $able6name

8(ERE &5NDII5N-1 9AND|5R: &5NDII5N-27

S0 () lause$


4R5M $able6name

8(ERE #l"mn6name IN ;


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SELE& S>M;#l"mn6name=

4R5M $able6name

8(ERE &5NDII5N

GR5> Y #l"mn6name7

S0 "!)T lause$

SELE& &5>N;#l"mn6name=

4R5M $able6name

8(ERE &5NDII5N7

S0 3*:()+ lause$

SELE& S>M;#l"mn6name=

4R5M $able6name

8(ERE &5NDII5N

GR5> Y #l"mn6name

(A?ING ;a)i$hema$i @"n$i#n #ndi$i#n=7

S0 R#*T# T*B# Statement$

&REAE ALE $able6name;

#l"mn1 da$a$,e

#l"mn2 da$a$,e

#l"mn3 da$a$,e.....

#l"mnN da$a$,e

RIMARY KEY; #ne #) m#)e #l"mns =

=7

S0 DR"2 T*B# Statement$

DR5 ALE $able6name7

S0 R#*T# ()D#; Statement $

&REAE >NI>E INDEB indeC6name

5N $able6name ; #l"mn1 #l"mn2...#l"mnN=7

S0 DR"2 ()D#; Statement $

ALER ALE $able6name


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DR5 INDEB indeC6name7

S0 D#S Statement $

DES& $able6name7

S0 TR!)*T# T*B# Statement$

R>N&AE ALE $able6name7

S0 *T#R T*B# Statement$

ALER ALE $able6name 9ADD|DR5|M5DI4Y: #l"mn6name 9da$a6,e:7

S0 *T#R T*B# Statement 5Rename7 $

ALER ALE $able6name RENAME 5 ne6$able6name7

S0 ()S#RT ()T" Statement$

INSER IN5 $able6name; #l"mn1 #l"mn2....#l"mnN=?AL>ES ; SE da$abase6name7

S0 "MM(T Statement$

&5MMI7


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S0 R"B*9 Statement$

R5LLA&K 7

Data 'ype

S0 data t&pe is an attribute that specifies t&pe of data of an& object. #achcolumn, %ariable and expression has related data t&pe in S0.

-ou would use these data t&pes while creating &our tables. -ou would choose a

particular data t&pe for a table column based on &our re1uirement.

S0 Ser%er offers six categories of data t&pes for &our use <

#xact )umeric Data T&pes

DATATYP !"#$ T#

bigint =>,??@,@?,A@,CE,,CAC >,??@,@?,A@,CE,,CA

int =?,E,EC@,EC ?,E,EC@,E

smallint =@?,C @?,

tin&int A ?

bit A

decimal =AG@C H AG@C =

numeric =AG@C H AG@C =

mone& =>??,@@,?A@,C,E.CAC H>??,@@,?A@,C,E.CA

smallmone& =?E,EC.@EC H?E,EC.@E


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*pproximate )umeric Data T&pes

DATA TYP !"#$ T#

float =.># H @AC .># H @AC

real [email protected]# H @C @.EA# H @C

Date and Time Data T&pes

DATA TYP !"#$ T#

datetime Ian , @ Dec @, >>>>

smalldatetime Ian , >AA Iun , ?A>

date Stores a date li'e Iune @A, >>

time Stores a time of da& li'e ?$@A 2.M.

%ote < 3ere, datetime has @.@@ milliseconds accurac& where as smalldatetime

has minute accurac&.

haracter Strings Data T&pes

DATA TYP Descri&tion

char Maximum length of C,AAA characters.5 Fixed length

non=!nicode characters7

%archar Maximum of C,AAA characters.5:ariable=length

non=!nicode data7.

%archar5max7 Maximum length of ?@characters, :ariable=lengthnon=!nicode data 5S0 Ser%er ?AA onl&7.

text :ariable=length non=!nicode data with a maximum


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length of ?,E,EC@,E characters.

!nicode haracter Strings Data T&pes


nchar Maximum length of E,AAA characters.5 Fixed length!nicode7

n%archar Maximum length of E,AAA characters.5:ariable length

!nicode7

n%archar5max7 Maximum length of ?@characters 5S0 Ser%er ?AA

onl&7.5 :ariable length !nicode7

ntext Maximum length of ,A@,E,C?@ characters.

5 :ariable length !nicode 7

Binar& Data T&pes


binar& Maximum length of C,AAA b&tes5Fixed=length binar&

data 7

%arbinar& Maximum length of C,AAA b&tes.5:ariable length

binar& data7

%arbinar&5max7 Maximum length of ?@ b&tes 5S0 Ser%er ?AA

onl&7. 5 :ariable length Binar& data7

image Maximum length of ?,E,EC@,E b&tes. 5 :ariablelength Binar& Data7

Misc Data T&pes



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s1lJ%ariant Stores %alues of %arious S0 Ser%er=supported datat&pes, except text, ntext, and timestamp.

timestamp Stores a database=wide uni1ue number that getsupdated e%er& time a row gets updated

uni1ueidentifier Stores a globall& uni1ue identifier 5+!(D7

xml Stores ;M data. -ou can store xml instances in a

column or a %ariable 5S0 Ser%er ?AA onl&7.

cursor Reference to a cursor object

table Stores a result set for later processing

4hat is an "perator in S0K

*n operator is a reser%ed word or a character used primaril& in an S0 statementLs

43#R# clause to perform operation5s7, such as comparisons and arithmetic

operations.

"perators are used to specif& conditions in an S0 statement and to ser%e asconjunctions for multiple conditions in a statement.

• *rithmetic operators

• omparison operators

• ogical operators

• "perators used to negate conditions

S0 *rithmetic "perators$

*ssume %ariable a holds A and %ariable b holds ?A, then$

#&erator Descri&tion xam&le


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H *ddition = *dds %alues on either side of theoperator

a H b willgi%e @A

= Subtraction = Subtracts right hand operand fromleft hand operand

a = b willgi%e =A

Multiplication = Multiplies %alues on either side of

the operator

a b will

gi%e ?AA

8 Di%ision = Di%ides left hand operand b& right hand

operand

b 8 a will

gi%e ?

N Modulus = Di%ides left hand operand b& right hand

operand and returns remainder

b N a will

gi%e A

S0 omparison "perators$

*ssume %ariable a holds A and %ariable b holds ?A, then$

#&erator Descri&tion xam&le

O hec's if the %alues of two operands are e1ual or

not, if &es then condition becomes true.

5a O b7 is

not true.

PO hec's if the %alues of two operands are e1ual or

not, if %alues are not e1ual then condition

becomes true.

5a PO b7 is

true.

Q hec's if the %alues of two operands are e1ual or

not, if %alues are not e1ual then conditionbecomes true.

5a Q b7 is

true.

hec's if the %alue of left operand is greater thanthe %alue of right operand, if &es then condition

becomes true.

5a b7 isnot true.

Q hec's if the %alue of left operand is less than the%alue of right operand, if &es then condition

5a Q b7 is


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becomes true. true.

O hec's if the %alue of left operand is greater than

or e1ual to the %alue of right operand, if &es thencondition becomes true.

5a O b7 is

not true.

QO hec's if the %alue of left operand is less than or

e1ual to the %alue of right operand, if &es thencondition becomes true.

5a QO b7 is

true.

PQ hec's if the %alue of left operand is not less thanthe %alue of right operand, if &es then condition

becomes true.

5a PQ b7 isfalse.

P hec's if the %alue of left operand is not greaterthan the %alue of right operand, if &es then

condition becomes true.

5a P b7 istrue.

S0 ogical "perators$

3ere is a list of all the logical operators a%ailable in S0.

#&erator Descri&tion

* The * operator is used to compare a %alue to all %alues inanother %alue set.

*)D The *)D operator allows the existence of multiple conditions

in an S0 statementLs 43#R# clause.

*)- The *)- operator is used to compare a %alue to an&

applicable %alue in the list according to the condition.

B#T4##) The B#T4##) operator is used to search for %alues that are

within a set of %alues, gi%en the minimum %alue and the

maximum %alue.

#;(STS The #;(STS operator is used to search for the presence of a


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row in a specified table that meets certain criteria.

() The () operator is used to compare a %alue to a list of literal

%alues that ha%e been specified.

(9# The (9# operator is used to compare a %alue to similar

%alues using wildcard operators.

)"T The )"T operator re%erses the meaning of the logical

operator with which it is used. #g$ )"T #;(STS, )"T

B#T4##), )"T (), etc. This is a ne'ate o&erator(

"R The "R operator is used to combine multiple conditions in an

S0 statementLs 43#R# clause.

(S )! The )! operator is used to compare a %alue with a )!

%alue.

!)(0!# The !)(0!# operator searches e%er& row of a specified tablefor uni1ueness 5no duplicates7.

x&ression

*n expression is a combination of one or more %alues, operators, and S0

functions that e%aluate to a %alue.

S0 #;2R#SS(")s are li'e formulas and the& are written in 1uer& language. -ou

can also use them to 1uer& the database for specific set of data.

S&ntax$

onsider the basic s&ntax of the S##T statement as follows$

SELE& #l"mn1 #l"mn2 #l"mnN

4R5M $able6name

8(ERE F&5NDII5N|EBRESSI5N7

There are different t&pes of S0 expressions, which are mentioned below$


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S0 = Boolean #xpressions$

S0 Boolean #xpressions fetch the data on the basis of matching single %alue.

Following is the s&ntax$


4R5M $able6name

8(ERE SINGLE ?AL>E MA&(ING EBRESSI5N7

onsider the !ST"M#RS table ha%ing the following records$

SLH SELE& 4R5M &>S5MERS7

+----+----------+-----+-----------+----------+

| ID | NAME | AGE | ADDRESS | SALARY |

+----+----------+-----+-----------+----------+

| 1 | Ramesh | 32 | Ahmedabad | 2000.00 || 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+* )#s in se$ ;0.00 se=

3ere is simple example showing usage of S0 Boolean #xpressions$

SLH SELE& 4R5M &>S5MERS 8(ERE SALARY 100007

+----+-------+-----+---------+----------+


+----+-------+-----+---------+----------+

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+-------+-----+---------+----------+

1 )# in se$ ;0.00 se=

S0 = )umeric #xpression$


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This expression is used to perform an& mathematical operation in an& 1uer&.

Following is the s&ntax$

SELE& n"me)ial6eC,)essi#n as 5ERAI5N6NAME

F4R5M $able6name

8(ERE &5NDII5N 7

3ere numericalJexpression is used for mathematical expression or an& formula.

Following is a simple examples showing usage of S0 )umeric #xpressions$

SLH SELE& ;1 + '= AS ADDII5N

+----------+

| ADDII5N |

+----------+

| 21 |+----------+

1 )# in se$ ;0.00 se=

There are se%eral built=in functions li'e a%g57, sum57, count57, etc., to perform

what is 'nown as aggregate data calculations against a table or a specific table

column.

SLH SELE& &5>N;= AS JRE&5RDSJ 4R5M &>S5MERS7

+---------+

| RE&5RDS |

+---------+

| * |

+---------+

1 )# in se$ ;0.00 se=

S0 = Date #xpressions$

Date #xpressions return current s&stem date and time %alues$

SLH SELE& &>RREN6IMESAM7

+---------------------+

| &"))en$6imes$am, |

+---------------------+


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| 200-11-12 0'%023 |

+---------------------+

1 )# in se$ ;0.00 se=

*nother date expression is as follows$

SLH SELE& GEDAE;=77+-------------------------+

| GEDAE |

+-------------------------+

| 200-10-22 120*1.1%0 |

+-------------------------+

1 )# in se$ ;0.00 se=

)"AT DATA*AS statement

The S0 )"AT DATA*AS statement is used to create new S0 database.


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S&ntax$

Basic s&ntax of R#*T# D*T*B*S# statement is as follows$

&REAE DAAASE Da$abaseName7

*lwa&s database name should be uni1ue within the RDBMS.

#xample$

(f &ou want to create new database QtestDB, then R#*T# D*T*B*S# statement

would be as follows$

SLH &REAE DAAASE $es$D7

Ma'e sure &ou ha%e admin pri%ilege before creating an& database. "nce a

database is created, &ou can chec' it in the list of databases as follows$

SLH S(58 DAAASES7+--------------------+

| Da$abase |

+--------------------+

| in@#)ma$i#n6shema |

| AMR55D |

| >5RIALS5IN |

| msl || #)i |

| $es$ |

| $es$D |

+--------------------+

* )#s in se$ ;0.00 se=

D"#P DATA*AS statement

The S0 D"#P DATA*AS statement is used to drop an existing database in S0

schema.


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S&ntax$

Basic s&ntax of DR"2 D*T*B*S# statement is as follows$

DR5 DAAASE Da$abaseName7


#xample$

(f &ou want to delete an existing database QtestDB, then DR"2 D*T*B*S#

statement would be as follows$

SLH DR5 DAAASE $es$D7

%#T+ Be careful before using this operation because b& deleting an existing

database would result in loss of complete information stored in the database.

Ma'e sure &ou ha%e admin pri%ilege before dropping an& database. "nce adatabase is dropped, &ou can chec' it in the list of databases as follows$

SLH S(58 DAAASES7

+--------------------+

| Da$abase |

+--------------------+

| in@#)ma$i#n6shema |

| AMR55D |

| >5RIALS5IN |

| msl |

| #)i |

| $es$ |

+--------------------+

' )#s in se$ ;0.00 se=

,S statement

4hen &ou ha%e multiple databases in &our S0 Schema, then before starting &our

operation, &ou would need to select a database where all the operations would be

performed.


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The S0 ,S statement is used to select an& existing database in S0 schema.

S&ntax$

Basic s&ntax of !S# statement is as follows$

>SE Da$abaseName7


)ow, if &ou want to wor' with *MR""D database, then &ou can execute the

following S0 command and start wor'ing with *MR""D database$

SLH >SE AMR55D7

reating a basic table in%ol%es naming the table and defining its columns and each

columnLs data t&pe.

)"AT TA*L statement

The S0 )"AT TA*L statement is used to create a new table.

S&ntax$

Basic s&ntax of R#*T# T*B# statement is as follows$

&REAE ALE $able6name;

#l"mn1 da$a$,e

#l"mn2 da$a$,e

#l"mn3 da$a$,e

.....

#l"mnN da$a$,e

RIMARY KEY; #ne #) m#)e #l"mns =

=7

R#*T# T*B# is the 'e&word telling the database s&stem what &ou want to do. (n

this case, &ou want to create a new table. The uni1ue name or identifier for the

table follows the R#*T# T*B# statement.

Then in brac'ets comes the list defining each column in the table and what sort of

data t&pe it is. The s&ntax becomes clearer with an example below.


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* cop& of an existing table can be created using a combination of the R#*T#

T*B# statement and the S##T statement. -ou can chec' complete details at

reate Table !sing another Table.

#xample$

Following is an example, which creates a !ST"M#RS table with (D as primar& 'e&

and )"T )! are the constraints showing that these fields can not be )! whilecreating records in this table$

SLH &REAE ALE &>S5MERS;

ID IN N5 N>LL

NAME ?AR&(AR ;20= N5 N>LL

AGE IN N5 N>LL

ADDRESS &(AR ;2=

SALARY DE&IMAL ;1 2= RIMARY KEY ;ID=

=7

-ou can %erif& if &our table has been created successfull& b& loo'ing at the

message displa&ed b& the S0 ser%er, otherwise &ou can use DS) command as

follows$

SLH DES& &>S5MERS7

+---------+---------------+------+-----+---------+-------+

| 4ield | ,e | N"ll | Ke | De@a"l$ | EC$)a |

+---------+---------------+------+-----+---------+-------+

| ID | in$;11= | N5 | RI | | |

| NAME | LL | |

| SALARY | deimal;12= | YES | | N>LL | |

+---------+---------------+------+-----+---------+-------+

)#s in se$ ;0.00 se=

)ow, &ou ha%e !ST"M#RS table a%ailable in &our database which &ou can use to

store re1uired information related to customers.

http://www.tutorialspoint.com/sql/sql-create-table-using-tables.htmhttp://www.tutorialspoint.com/sql/sql-create-table-using-tables.htm


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S0 D"#P TA*L statement

The S0 D"#P TA*L statement is used to remo%e a table definition and all data,

indexes, triggers, constraints, and permission specifications for that table.

%#T+ -ou ha%e to be careful while using this command because once a table is

deleted then all the information a%ailable in the table would also be lost fore%er.

S&ntax$

Basic s&ntax of DR"2 T*B# statement is as follows$

DR5 ALE $able6name7

#xample$

et us first %erif& !ST"M#RS table and then we would delete it from the

database$

SLH DES& &>S5MERS7

+---------+---------------+------+-----+---------+-------+

| 4ield | ,e | N"ll | Ke | De@a"l$ | EC$)a |

+---------+---------------+------+-----+---------+-------+

| ID | in$;11= | N5 | RI | | |

| NAME | LL | |

| SALARY | deimal;12= | YES | | N>LL | |

+---------+---------------+------+-----+---------+-------+

)#s in se$ ;0.00 se=

This means !ST"M#RS table is a%ailable in the database, so let us drop it as

follows$

SLH DR5 ALE &>S5MERS7

"e) 5K 0 )#s a/e$ed ;0.01 se=

)ow, if &ou would tr& D#S command, then &ou would get error as follows$

SLH DES& &>S5MERS7

ERR5R 11%' ;%2S02= able OES.&>S5MERSO d#esnO$ eCis$


23/62

3ere, T#ST is database name which we are using for our examples.

-%S"T -%T# Statement

The S0 -%S"T -%T# Statement is used to add new rows of data to a table in

the database.

S&ntax$

There are two basic s&ntaxes of ()S#RT ()T" statement as follows$

INSER IN5 ALE6NAME ;#l"mn1 #l"mn2 #l"mn3...#l"mnN=

?AL>ES ;


24/62

-ou can populate data into a table through select statement o%er another table

pro%ided another table has a set of fields, which are re1uired to populate first

table. 3ere is the s&ntax$

INSER IN5 P)s$6$able6name F;#l"mn1 #l"mn2 ... #l"mnN=

SELE& #l"mn1 #l"mn2 ...#l"mnN

4R5M se#nd6$able6name

F8(ERE #ndi$i#n7

SL)T statement

S0 SL)T statement is used to fetch the data from a database table which

returns data in the form of result table. These result tables are called result=sets.

S&ntax$

The basic s&ntax of S##T statement is as follows$

SELE& #l"mn1 #l"mn2 #l"mnN 4R5M $able6name7

3ere, column, column?...are the fields of a table whose %alues &ou want to fetch.

(f &ou want to fetch all the fields a%ailable in the field, then &ou can use the

following s&ntax$

SELE& 4R5M $able6name7

#xample$

Following is an example, which would fetch (D, )ame and Salar& fields of the

customers a%ailable in !ST"M#RS table$

SLH SELE& ID NAME SALARY 4R5M &>S5MERS7

This would produce the following result$

(f &ou want to fetch all the fields of !ST"M#RS table, then use the following

1uer&$

SLH SELE& 4R5M &>S5MERS7


25/62

The S0 W." clause is used to specif& a condition while fetching the data from

single table or joining with multiple tables.

(f the gi%en condition is satisfied then onl& it returns specific %alue from the table.

-ou would use 43#R# clause to filter the records and fetching onl& necessar&

records.

The 43#R# clause is not onl& used in S##T statement, but it is also used in

!2D*T#, D##T# statement, etc., which we would examine in subse1uent

chapters.

S&ntax$

The basic s&ntax of S##T statement with 43#R# clause is as follows$


4R5M $able6name

8(ERE F#ndi$i#n

-ou can specif& a condition using comparison or logical operators li'e , Q, O,

(9#, )"T, etc. Below examples would ma'e this concept clear.

#xample$


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

http://www.tutorialspoint.com/sql/sql-operators.htmhttp://www.tutorialspoint.com/sql/sql-operators.htm


26/62

Following is an example which would fetch (D, )ame and Salar& fields from the

!ST"M#RS table where salar& is greater than ?AAA$

SLH SELE& ID NAME SALARY

4R5M &>S5MERS

8(ERE SALARY H 20007


+----+----------+----------+

| ID | NAME | SALARY |

+----+----------+----------+

| % | &hai$ali | '00.00 |

| | (a)di! | 00.00 |

| ' | K#mal | %00.00 || * | M"/ | 10000.00 |

+----+----------+----------+

Following is an example, which would fetch (D, )ame and Salar& fields from the

!ST"M#RS table for a customer with name .ardi/. 3ere, it is important to note

that all the strings should be gi%en inside single 1uotes 5LL7 where as numeric

%alues should be gi%en without an& 1uote as in abo%e example$


4R5M &>S5MERS

8(ERE NAME O(a)di!O7


+----+----------+----------+


+----+----------+----------+| | (a)di! | 00.00 |

+----+----------+----------+


27/62

The S0 A%D and #" operators are used to combine multiple conditions to

narrow data in an S0 statement. These two operators are called conjuncti%e

operators.

These operators pro%ide a means to ma'e multiple comparisons with different

operators in the same S0 statement.

The *)D "perator$

The A%D operator allows the existence of multiple conditions in an S0

statementLs 43#R# clause.

S&ntax$

The basic s&ntax of *)D operator with 43#R# clause is as follows$


4R5M $able6name

8(ERE F#ndi$i#n1 AND F#ndi$i#n2...AND F#ndi$i#nN7

-ou can combine ) number of conditions using *)D operator. For an action to be

ta'en b& the S0 statement, whether it be a transaction or 1uer&, all conditions

separated b& the *)D must be TR!#.

#xample$


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+


28/62


!ST"M#RS table where salar& is greater than ?AAA *)D age is less tan ? &ears$


4R5M &>S5MERS

8(ERE SALARY H 2000 AND ae Q 27


+----+-------+----------+


+----+-------+----------+

| ' | K#mal | %00.00 |

| * | M"/ | 10000.00 |

+----+-------+----------+

The "R "perator$

The "R operator is used to combine multiple conditions in an S0 statementLs

43#R# clause.

S&ntax$

The basic s&ntax of "R operator with 43#R# clause is as follows$

SELE& #l"mn1 #l"mn2 #l"mnN4R5M $able6name

8(ERE F#ndi$i#n1 5R F#ndi$i#n2...5R F#ndi$i#nN

-ou can combine ) number of conditions using "R operator. For an action to be

ta'en b& the S0 statement, whether it be a transaction or 1uer&, onl& an& ")# of

the conditions separated b& the "R must be TR!#.

#xample$


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+



29/62

| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |+----+----------+-----+-----------+----------+


!ST"M#RS table where salar& is greater than ?AAA "R age is less tan ? &ears$


4R5M &>S5MERS

8(ERE SALARY H 2000 5R ae Q 27


+----+----------+----------+


+----+----------+----------+

| 3 | !a"shi! | 2000.00 |

| % | &hai$ali | '00.00 |

| | (a)di! | 00.00 |

| ' | K#mal | %00.00 |

| * | M"/ | 10000.00 |

+----+----------+----------+

,PDAT 0uer&

The S0 ,PDAT 0uer& is used to modif& the existing records in a table.

-ou can use 43#R# clause with !2D*T# 1uer& to update selected rows otherwise

all the rows would be affected.

S&ntax$

The basic s&ntax of !2D*T# 1uer& with 43#R# clause is as follows$


30/62

>DAE $able6name

SE #l"mn1 DAE &>S5MERS

SE ADDRESS O"neO

8(ERE ID '7

)ow, !ST"M#RS table would ha%e the following records$

+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |


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| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | "ne | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

(f &ou want to modif& all *DDR#SS and S**R- column %alues in !ST"M#RS

table, &ou do not need to use 43#R# clause and !2D*T# 1uer& would be as

follows$

SLH >DAE &>S5MERS

SE ADDRESS O"neO SALARY 1000.007


+----+----------+-----+---------+---------+


+----+----------+-----+---------+---------+

| 1 | Ramesh | 32 | "ne | 1000.00 |

| 2 | Khilan | 2 | "ne | 1000.00 |

| 3 | !a"shi! | 23 | "ne | 1000.00 |

| % | &hai$ali | 2 | "ne | 1000.00 |

| | (a)di! | 2* | "ne | 1000.00 |

| ' | K#mal | 22 | "ne | 1000.00 |

| * | M"/ | 2% | "ne | 1000.00 |

+----+----------+-----+---------+---------+

DLT 0uer&

The S0 DLT 0uer& is used to delete the existing records from a table.

-ou can use 43#R# clause with D##T# 1uer& to delete selected rows, otherwise

all the records would be deleted.

S&ntax$

The basic s&ntax of D##T# 1uer& with 43#R# clause is as follows$


32/62

DELEE 4R5M $able6name

8(ERE F#ndi$i#n7

-ou can combine ) number of conditions using *)D or "R operators.

#xample$


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

Following is an example, which would D##T# a customer, whose (D is $

SLH DELEE 4R5M &>S5MERS8(ERE ID '7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |


33/62

+----+----------+-----+-----------+----------+

(f &ou want to D##T# all the records from !ST"M#RS table, &ou do not need to

use 43#R# clause and D##T# 1uer& would be as follows$

SLH DELEE 4R5M &>S5MERS7

)ow, !ST"M#RS table would not ha%e an& record.

S0 L-0 clause

The S0 L-0 clause is used to compare a %alue to similar %alues using wildcard

operators. There are two wildcards used in conjunction with the (9# operator$

• The percent sign 5N7

• The underscore 5J7

The percent sign represents /ero, one, or multiple characters. The underscore

represents a single number or character. The s&mbols can be used in

combinations.

S&ntax$

The basic s&ntax of N and J is as follows$

SELE& 4R5M $able6name

8(ERE #l"mn LIKE OBBBBO

#)


8(ERE #l"mn LIKE OBBBBO

#)


8(ERE #l"mn LIKE OBBBB6O

#)


34/62


8(ERE #l"mn LIKE O6BBBBO

#)


8(ERE #l"mn LIKE O6BBBB6O

-ou can combine ) number of conditions using *)D or "R operators. 3ere, ;;;;

could be an& numeric or string %alue.

#xample$

3ere are number of examples showing 43#R# part ha%ing different (9# clause

with LNL and LJL operators$

Statement Descri&tion

43#R# S**R- (9#

L?AANL

Finds an& %alues that start with ?AA

43#R# S**R- (9#

LN?AANL

Finds an& %alues that ha%e ?AA in an& position

43#R# S**R- (9#

LJAANL

Finds an& %alues that ha%e AA in the second and

third positions

43#R# S**R- (9#L?JNJNL

Finds an& %alues that start with ? and are atleast @ characters in length

43#R# S**R- (9#LN?L

Finds an& %alues that end with ?

43#R# S**R- (9#

LJ?N@L

Finds an& %alues that ha%e a ? in the second

position and end with a @


35/62

43#R# S**R- (9#L?JJJ@L

Finds an& %alues in a fi%e=digit number that startwith ? and end with @

et us ta'e a real example, consider the !ST"M#RS table ha%ing the following

records$


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 || ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

Following is an example, which would displa& all the records from !ST"M#RS

table where S**R- starts with ?AA$

SLH SELE& 4R5M &>S5MERS

8(ERE SALARY LIKE O200O7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 3 | !a"shi! | 23 | K#$a | 2000.00 |

+----+----------+-----+-----------+----------+

The S0 T#P clause is used to fetch a T"2 ) number or ; percent records from a

table.


36/62

%ote+ *ll the databases do not support T"2 clause. For example M&S0

supports L-$-T clause to fetch limited number of records and "racle

uses"#W%,$ to fetch limited number of records.

S&ntax$

The basic s&ntax of T"2 clause with S##T statement would be as follows$

SELE& 5 n"mbe)|,e)en$ #l"mn6name;s=

4R5M $able6name

8(ERE F#ndi$i#n

#xample$


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 || * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

Following is an example on S0 ser%er, which would fetch top @ records from

!ST"M#RS table$

SLH SELE& 5 3 4R5M &>S5MERS7


+----+---------+-----+-----------+---------+


+----+---------+-----+-----------+---------+



37/62

| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

+----+---------+-----+-----------+---------+

(f &ou are using M&S0 ser%er, then here is an e1ui%alent example$

SLH SELE& 4R5M &>S5MERSLIMI 37


+----+---------+-----+-----------+---------+


+----+---------+-----+-----------+---------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

+----+---------+-----+-----------+---------+

(f &ou are using "racle ser%er, then here is an e1ui%alent example$


8(ERE R58N>M Q 37


+----+---------+-----+-----------+---------+


+----+---------+-----+-----------+---------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |+----+---------+-----+-----------+---------+

The SQL ORDER BY clause is used to sort the data in ascending or descending order, based on one ormore columns. Some database sorts query results in ascending order by deault.


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Synta!"The basic synta! o ORDER BY clause is as ollo#s"

SELE$T column%list

&RO' table(name)*+ERE condition

)ORDER BY column-, column, .. column/ )0S$ 1 DES$2

You can use more than one column in the ORDER BY clause. 'a3e sure #hate4er column you are using

to sort, that column should be in column%list.

E!am5le"$onsider the $6STO'ERS table ha4ing the ollo#ing records"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%71 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 1

1 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7&ollo#ing is an e!am5le, #hich #ould sort the result in ascending order by /0'E and S0L0RY"

SQLC SELE$T &RO' $6STO'ERS

ORDER BY /0'E, S0L0RY2This #ould 5roduce the ollo#ing result"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%71 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 > 1 $haitali 1 = 1 'umbai 1 ?=;;.;; 11 = 1 +ardi3 1 @ 1 Bho5al 1 A=;;.;; 1

1 : 1 3aushi3 1 : 1 1 8ndore 1 -;;;;.;; 1

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7&ollo#ing is an e!am5le, #hich #ould sort the result in descending order by /0'E"

SQLC SELE$T &RO' $6STO'ERS ORDER BY /0'E DES$2

This #ould 5roduce the ollo#ing result"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7


39/62

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 11 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

1 ? 1


40/62

First, let us see how the following S##T 1uer& returns duplicate salar& records$

SLH SELE& SALARY 4R5M &>S5MERS

5RDER Y SALARY7

This would produce the following result where salar& ?AAA is coming twice which is

a duplicate record from the original table.

+----------+

| SALARY |

+----------+

| 100.00 |

| 2000.00 |

| 2000.00 |

| %00.00 || '00.00 |

| 00.00 |

| 10000.00 |

+----------+

)ow, let us use D(ST()T 'e&word with the abo%e S##T 1uer& and see the

result$

SLH SELE& DISIN& SALARY 4R5M &>S5MERS

5RDER Y SALARY7

This would produce the following result where we do not ha%e an& duplicate entr&$

+----------+

| SALARY |

+----------+

| 100.00 |

| 2000.00 |

| %00.00 |

| '00.00 |

| 00.00 |


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| 10000.00 |

+----------+

The S0 #"D" *Y clause is used to sort the data in ascending or descending

order, based on one or more columns. Some database sorts 1uer& results in

ascending order b& default.

S&ntax$

The basic s&ntax of "RD#R B- clause which would be used to sort result in

ascending or descending order is as follows$

SELE& #l"mn-lis$

4R5M $able6name

F8(ERE #ndi$i#n F5RDER Y #l"mn1 #l"mn2 .. #l"mnN FAS& | DES&7

-ou can use more than one column in the "RD#R B- clause. Ma'e sure whate%er

column &ou are using to sort, that column should be in column=list.

#xample$



+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

Following is an example, which would sort the result in ascending order b& )*M#

and S**R-$


42/62


5RDER Y NAME SALARY7


+----+----------+-----+-----------+----------+

| ID | NAME | AGE | ADDRESS | SALARY |+----+----------+-----+-----------+----------+

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| 2 | Khilan | 2 | Delhi | 100.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |


+----+----------+-----+-----------+----------+

Following is an example, which would sort the result in descending order b& )*M#$


5RDER Y NAME DES&7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| * | M"/ | 2% | Ind#)e | 10000.00 |

| ' | K#mal | 22 | M | %00.00 |

| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

+----+----------+-----+-----------+----------+


43/62

To fetch the rows with own preferred order, the S##T 1uer& would as follows$


5RDER Y ;&ASE ADDRESS

8(EN ODEL(IO (EN 1

8(EN O(5ALO (EN 2

8(EN OK5AO (EN 3

8(EN OA(MADAADO (EN %

8(EN OMO (EN

ELSE 100 END= AS& ADDRESS DES&7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+

| 2 | Khilan | 2 | Delhi | 100.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| ' | K#mal | 22 | M | %00.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 || 1 | Ramesh | 32 | Ahmedabad | 2000.00 |

+----+----------+-----+-----------+----------+

This will sort customers b& *DDR#SS in &our owno"rder of preference first and in

a natural order for the remaining addresses. *lso remaining *ddresses will be

sorted in the re%erse alpha order.

Constraints

$onstraints are the rules enorced on data columns on table. These are used to limit the ty5e o data thatcan go into a table. This ensures the accuracy and reliability o the data in the database.

$onstraints could be column le4el or table le4el. $olumn le4el constraints are a55lied only to one

column, #hereas table le4el constraints are a55lied to the #hole table.

&ollo#ing are commonly used constraints a4ailable in SQL. These constraints ha4e already been

discussed in SQL % RDB'S $once5ts cha5ter but its #orth to re4ise them at this 5oint.


44/62

/OT /6LL $onstraint" Ensures that a column cannot ha4e /6LL 4alue.

DE&06LT $onstraint" ro4ides a deault 4alue or a column #hen none is s5eciied.

6/8Q6E $onstraint" Ensures that all 4alues in a column are dierent.

R8'0RY


45/62

+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 || % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

5b7 *nother table is "RD#RS as follows$

+-----+---------------------+-------------+--------+

|5ID | DAE | &>S5MER6ID | AM5>N |

+-----+---------------------+-------------+--------+

| 102 | 200-10-0 000000 | 3 | 3000 |

| 100 | 200-10-0 000000 | 3 | 100 |

| 101 | 200-11-20 000000 | 2 | 1'0 |

| 103 | 200-0-20 000000 | % | 20'0 |

+-----+---------------------+-------------+--------+

)ow, let us join these two tables in our S##T statement as follows$

SLH SELE& ID NAME AGE AM5>N

4R5M &>S5MERS 5RDERS

8(ERE &>S5MERS.ID 5RDERS.&>S5MER6ID7


+----+----------+-----+--------+

| ID | NAME | AGE | AM5>N |

+----+----------+-----+--------+

| 3 | !a"shi! | 23 | 3000 |


46/62

| 3 | !a"shi! | 23 | 100 |

| 2 | Khilan | 2 | 1'0 |

| % | &hai$ali | 2 | 20'0 |

+----+----------+-----+--------+

3ere, it is noticeable that the join is performed in the 43#R# clause. Se%eral

operators can be used to join tables, such as O, Q, , Q, QO, O, PO, B#T4##),

(9#, and )"T6 the& can all be used to join tables. 3owe%er, the most common

operator is the e1ual s&mbol.

S0 Ioin T&pes$

There are different t&pes of joins a%ailable in S0$

• ())#R I"()$ returns rows when there is a match in both tables.

•

#FT I"()$ returns all rows from the left table, e%en if there are no matchesin the right table.

• R(+3T I"()$ returns all rows from the right table, e%en if there are no

matches in the left table.

• F! I"()$ returns rows when there is a match in one of the tables.

• S#F I"()$ is used to join a table to itself as if the table were two tables,

temporaril& renaming at least one table in the S0 statement.

• *RT#S(*) I"()$ returns the artesian product of the sets of records from

the two or more joined tables.

The most requently used and im5ortant o the Ioins is the 8//ER JO8/. They are also reerred to as anEQ68JO8/.

The 8//ER JO8/ creates a ne# result table by combining column 4alues o t#o tables Gtable- andtableH based u5on the Ioin%5redicate. The query com5ares each ro# o table- #ith each ro# o table to

ind all 5airs o ro#s #hich satisy the Ioin%5redicate. *hen the Ioin%5redicate is satisied, column 4alues

or each matched 5air o ro#s o 0 and B are combined into a result ro#.

Synta!"

The basic synta! o 8//ER JO8/ is as ollo#s"

SELE$T table-.column-, table.column...

&RO' table-

8//ER JO8/ table

http://www.tutorialspoint.com/sql/sql-inner-joins.htmhttp://www.tutorialspoint.com/sql/sql-left-joins.htmhttp://www.tutorialspoint.com/sql/sql-right-joins.htmhttp://www.tutorialspoint.com/sql/sql-full-joins.htmhttp://www.tutorialspoint.com/sql/sql-self-joins.htmhttp://www.tutorialspoint.com/sql/sql-cartesian-joins.htmhttp://www.tutorialspoint.com/sql/sql-inner-joins.htmhttp://www.tutorialspoint.com/sql/sql-left-joins.htmhttp://www.tutorialspoint.com/sql/sql-right-joins.htmhttp://www.tutorialspoint.com/sql/sql-full-joins.htmhttp://www.tutorialspoint.com/sql/sql-self-joins.htmhttp://www.tutorialspoint.com/sql/sql-cartesian-joins.htm


47/62

O/ table-.common(ield K table.common(ield2E!am5le"

$onsider the ollo#ing t#o tables, GaH $6STO'ERS table is as ollo#s"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%71 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 1

1 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 17%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

GbH 0nother table is ORDERS as ollo#s"

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71 O8D 1 D0TE 1 8D 1 0'O6/T 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 11 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 1

1 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 17%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, let us Ioin these t#o tables using 8//ER JO8/ as ollo#s"

SQLC SELE$T 8D, /0'E, 0'O6/T, D0TE &RO' $6STO'ERS

8//ER JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D2This #ould 5roduce the ollo#ing result"

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 : 1 3aushi3 1 :;;; 1 ;;%-;%;A ;;";;";; 11 : 1 3aushi3 1 -=;; 1 ;;%-;%;A ;;";;";; 1

1 1 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

The SQL LE&T JO8/ returns all ro#s rom the let table, e4en i there are no matches in the right table.

This means that i the O/ clause matches ; GMeroH records in right table, the Ioin #ill still return a ro# inthe result, but #ith /6LL in each column rom right table.


48/62

This means that a let Ioin returns all the 4alues rom the let table, 5lus matched 4alues rom the righttable or /6LL in case o no matching Ioin 5redicate.

Synta!"

The basic synta! o LE&T JO8/ is as ollo#s"


&RO' table-

LE&T JO8/ tableO/ table-.common(ield K table.common(ield2

+ere gi4en condition could be any gi4en e!5ression based on your requirement.

E!am5le"


7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%71 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 11 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7


7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1 O8D 1 D0TE 1 $6STO'ER(8D 1 0'O6/T 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 1

1 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 11 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, let us Ioin these t#o tables using LE&T JO8/ as ollo#s"

SQLC SELE$T 8D, /0'E, 0'O6/T, D0TE

&RO' $6STO'ERS

LE&T JO8/ ORDERS O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D2


7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 - 1 Ramesh 1 /6LL 1 /6LL 1

1 1


49/62

1 : 1 3aushi3 1 -=;; 1 ;;%-;%;A ;;";;";; 11 > 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 = 1 +ardi3 1 /6LL 1 /6LL 1

1 ? 1


50/62

+----+----------+-----+-----------+----------+

5b7 *nother table is "RD#RS as follows$

+-----+---------------------+-------------+--------+

|5ID | DAE | &>S5MER6ID | AM5>N |

+-----+---------------------+-------------+--------+| 102 | 200-10-0 000000 | 3 | 3000 |

| 100 | 200-10-0 000000 | 3 | 100 |

| 101 | 200-11-20 000000 | 2 | 1'0 |

| 103 | 200-0-20 000000 | % | 20'0 |

+-----+---------------------+-------------+--------+

)ow, let us join these two tables using R(+3T I"() as follows$

SLH SELE& ID NAME AM5>N DAE

4R5M &>S5MERS

RIG( 5IN 5RDERS

5N &>S5MERS.ID 5RDERS.&>S5MER6ID7


+------+----------+--------+---------------------+

| ID | NAME | AM5>N | DAE |

+------+----------+--------+---------------------+

| 3 | !a"shi! | 3000 | 200-10-0 000000 |

| 3 | !a"shi! | 100 | 200-10-0 000000 |

| 2 | Khilan | 1'0 | 200-11-20 000000 |

| % | &hai$ali | 20'0 | 200-0-20 000000 |

+------+----------+--------+---------------------+

The SQL &6LL JO8/ combines the results o both let and right outer Ioins.

The Ioined table #ill contain all records rom both tables, and ill in /6LLs or missing matches oneither side.


51/62

Synta!"The basic synta! o &6LL JO8/ is as ollo#s"


&RO' table-&6LL JO8/ table

O/ table-.common(ield K table.common(ield2


E!am5le"


7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 17%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 11 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7


7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1O8D 1 D0TE 1 $6STO'ER(8D 1 0'O6/T 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 1

1 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 11 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, let us Ioin these t#o tables using &6LL JO8/ as ollo#s"


&RO' $6STO'ERS &6LL JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D2


7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 - 1 Ramesh 1 /6LL 1 /6LL 1

1 1 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 = 1 +ardi3 1 /6LL 1 /6LL 1


52/62

1 ? 1


53/62

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | %00.00 |

| * | M"/ | 2% | Ind#)e | 10000.00 |

+----+----------+-----+-----------+----------+

)ow, let us join this table using S#F I"() as follows$

SLH SELE& a.ID b.NAME a.SALARY

4R5M &>S5MERS a &>S5MERS b

8(ERE a.SALARY Q b.SALARY7


+----+----------+---------+


+----+----------+---------+

| 2 | Ramesh | 100.00 |

| 2 | !a"shi! | 100.00 |

| 1 | &hai$ali | 2000.00 |

| 2 | &hai$ali | 100.00 |

| 3 | &hai$ali | 2000.00 |

| ' | &hai$ali | %00.00 |

| 1 | (a)di! | 2000.00 |

| 2 | (a)di! | 100.00 |

| 3 | (a)di! | 2000.00 |

| % | (a)di! | '00.00 |

| ' | (a)di! | %00.00 |

| 1 | K#mal | 2000.00 |

| 2 | K#mal | 100.00 |

| 3 | K#mal | 2000.00 |

| 1 | M"/ | 2000.00 |

| 2 | M"/ | 100.00 |

| 3 | M"/ | 2000.00 |


54/62

| % | M"/ | '00.00 |

| | M"/ | 00.00 |

| ' | M"/ | %00.00 |

+----+----------+---------+

The $0RTES80/ JO8/ or $ROSS JO8/ returns the $artesian 5roduct o the sets o records rom the

t#o or more Ioined tables. Thus, it equates to an inner Ioin #here the Ioin%condition al#ays e4aluates to

True or #here the Ioin%condition is absent rom the statement.

Synta!"

The basic synta! o $0RTES80/ JO8/ or $ROSS JO8/ is as ollo#s"


&RO' table-, table ), table: E!am5le"$onsider the ollo#ing t#o tables, GaH $6STO'ERS table is as ollo#s"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%71 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 11 1 =;;.;; 1

1 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7GbH 0nother table is ORDERS as ollo#s"

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71O8D 1 D0TE 1 $6STO'ER(8D 1 0'O6/T 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 11 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 1

1 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7 /o#, let us Ioin these t#o tables using 8//ER JO8/ as ollo#s"

SQLC SELE$T 8D, /0'E, 0'O6/T, D0TE &RO' $6STO'ERS, ORDERS2



55/62

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 - 1 Ramesh 1 :;;; 1 ;;%-;%;A ;;";;";; 1

1 - 1 Ramesh 1 -=;; 1 ;;%-;%;A ;;";;";; 11 - 1 Ramesh 1 -=?; 1 ;;%--%; ;;";;";; 1

1 - 1 Ramesh 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 1 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 = 1 +ardi3 1 :;;; 1 ;;%-;%;A ;;";;";; 11 = 1 +ardi3 1 -=;; 1 ;;%-;%;A ;;";;";; 11 = 1 +ardi3 1 -=?; 1 ;;%--%; ;;";;";; 1

1 = 1 +ardi3 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 ? 1


56/62

)*+ERE condition

6/8O/

SELE$T column- ), column &RO' table- ), table

)*+ERE condition


E!am5le"


7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 17%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 11 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7


7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1O8D 1 D0TE 1 $6STO'ER(8D 1 0'O6/T 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%71 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 1

1 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 11 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, let us Ioin these t#o tables in our SELE$T statement as ollo#s"


&RO' $6STO'ERS LE&T JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D

6/8O/

SELE$T 8D, /0'E, 0'O6/T, D0TE &RO' $6STO'ERS

R89+T JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D2This #ould 5roduce the ollo#ing result"

7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 - 1 Ramesh 1 /6LL 1 /6LL 1


57/62

1 1 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 = 1 +ardi3 1 /6LL 1 /6LL 11 ? 1


58/62

1 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 17%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, let us Ioin these t#o tables in our SELE$T statement as ollo#s"

SQLC SELE$T 8D, /0'E, 0'O6/T, D0TE &RO' $6STO'ERS

LE&T JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D

6/8O/ 0LL SELE$T 8D, /0'E, 0'O6/T, D0TE

&RO' $6STO'ERS R89+T JO8/ ORDERS

O/ $6STO'ERS.8D K ORDERS.$6STO'ER(8D2


7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%7

1 8D 1 /0'E 1 0'O6/T 1 D0TE 1

7%%%%%%7%%%%%%%%%%7%%%%%%%%7%%%%%%%%%%%%%%%%%%%%%71 - 1 Ramesh 1 /6LL 1 /6LL 1

1 1 1 $haitali 1 ;?; 1 ;;A%;=%; ;;";;";; 1

1 = 1 +ardi3 1 /6LL 1 /6LL 11 ? 1


59/62

S&ntax$

The basic s&ntax of %,LL while creating a table$

SLH &REAE ALE &>S5MERS;

ID IN N5 N>LL

NAME ?AR&(AR ;20= N5 N>LL

AGE IN N5 N>LL

ADDRESS &(AR ;2=

SALARY DE&IMAL ;1 2=

RIMARY KEY ;ID=

=7

3ere, %#T %,LL signifies that column should alwa&s accept an explicit %alue of

the gi%en data t&pe. There are two columns where we did not use )"T )!,

which means these columns could be )!.

* field with a )! %alue is one that has been left blan' during record creation.

#xample$

The )! %alue can cause problems when selecting data, howe%er, because when

comparing an un'nown %alue to an& other %alue, the result is alwa&s un'nown and

not included in the final results.

-ou must use the -S %,LL or -S %#T %,LL operators in order to chec' for a)! %alue.

onsider the following table, !ST"M#RS ha%ing the following records$

+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

| ' | K#mal | 22 | M | |


60/62

| * | M"/ | 2% | Ind#)e | |

+----+----------+-----+-----------+----------+

)ow, following is the usage of -S %#T %,LL operator$

SLH SELE& ID NAME AGE ADDRESS SALARY

4R5M &>S5MERS 8(ERE SALARY IS N5 N>LL7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+


| 2 | Khilan | 2 | Delhi | 100.00 |

| 3 | !a"shi! | 23 | K#$a | 2000.00 |

| % | &hai$ali | 2 | M"mbai | '00.00 |

| | (a)di! | 2* | h#,al | 00.00 |

+----+----------+-----+-----------+----------+

)ow, following is the usage of -S %,LL operator$

SLH SELE& ID NAME AGE ADDRESS SALARY

4R5M &>S5MERS

8(ERE SALARY IS N>LL7


+----+----------+-----+-----------+----------+


+----+----------+-----+-----------+----------+| ' | K#mal | 22 | M | |

| * | M"/ | 2% | Ind#)e | |

+----+----------+-----+-----------+----------+

rename table


61/62

You can rename a table or a column tem5orarily by gi4ing another name 3no#n as alias.

The use o table aliases means to rename a table in a 5articular SQL statement. The renaming is a

tem5orary change and the actual table name does not change in the database.

The column aliases are used to rename a tableNs columns or the 5ur5ose o a 5articular SQL query.

Synta!"The basic synta! o table alias is as ollo#s"

SELE$T column-, column....

&RO' table(name 0S alias(name

*+ERE )condition2The basic synta! o column alias is as ollo#s"

SELE$T column(name 0S alias(name

&RO' table(name*+ERE )condition2

E!am5le"$onsider the ollo#ing t#o tables, GaH $6STO'ERS table is as ollo#s"

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 8D 1 /0'E 1 09E 1 0DDRESS 1 S0L0RY 17%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7

1 - 1 Ramesh 1 : 1 0hmedabad 1 ;;;.;; 1

1 1 =;;.;; 11 @ 1 'uy 1 > 1 8ndore 1 -;;;;.;; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%%%%7%%%%%%%%%%7


7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1O8D 1 D0TE 1 $6STO'ER(8D 1 0'O6/T 17%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

1 -; 1 ;;%-;%;A ;;";;";; 1 : 1 :;;; 1

1 -;; 1 ;;%-;%;A ;;";;";; 1 : 1 -=;; 1

1 -;- 1 ;;%--%; ;;";;";; 1 1 -=?; 11 -;: 1 ;;A%;=%; ;;";;";; 1 > 1 ;?; 1

7%%%%%7%%%%%%%%%%%%%%%%%%%%%7%%%%%%%%%%%%%7%%%%%%%%7

/o#, ollo#ing is the usage o table alias"

SQLC SELE$T $.8D, $./0'E, $.09E, O.0'O6/T

&RO' $6STO'ERS 0S $, ORDERS 0S O *+ERE $.8D K O.$6STO'ER(8D2



62/62

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%71 8D 1 /0'E 1 09E 1 0'O6/T 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%7

1 : 1 3aushi3 1 : 1 :;;; 1

1 : 1 3aushi3 1 : 1 -=;; 11 1 1 $haitali 1 = 1 ;?; 1

7%%%%7%%%%%%%%%%7%%%%%7%%%%%%%%7

&ollo#ing is the usage o column alias"

SQLC SELE$T 8D 0S $6STO'ER(8D, /0'E 0S $6STO'ER(/0'E &RO' $6STO'ERS

*+ERE S0L0RY 8S /OT /6LL2


7%%%%%%%%%%%%%7%%%%%%%%%%%%%%%7

1 $6STO'ER(8D 1 $6STO'ER(/0'E 1

7%%%%%%%%%%%%%7%%%%%%%%%%%%%%%71 - 1 Ramesh 1

1 1 1 $haitali 1

1 = 1 +ardi3 1

1 ? 1

what is sql1

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