chapter04 rev

7/18/2019 Chapter04 Rev

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McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc !llrights reser"e#

Chapter 4

Query Formulation with SQL



4-2

Outline

Background

Getting started

Joining tables Summariing tables

!roblem sol"ing guidelines

#d"anced problems

$ata manipulation statements



4-3

%hat is SQL&

Structured Query Language

Language 'or database de'inition(

manipulation( and control

)nternational standard

Standalone and embedded usage

)ntergalactic database speak



4-4

SQL Statements

Statement Chapter

C*+#,+ ,#BL+ -( ./

S+L+C, -( 0( .1

)2S+*,( 3!$#,+ -( .1

$+L+,+ -( 0( .1

C*+#,+ )+% .1

C*+#,+ ,*)GG+* ..G*#2,( *+O5+ .4

CO66),( *OLLB#C5 .7

C*+#,+ ,8!+ ./



4-5

SQL Standardiation

*elati"ely simple standard9 SQL:/; and

re"ision <SQL:/0=

6odestly comple> standard9 SQL:0?

Comple> standards9 SQL9.000 and

SQL9?11-



4-6

SQL Con'ormance

2o o''icial con'ormance testing

endor claims about con'ormance

*easonable con'ormance on Core SQL Large "ariance on con'ormance outside o'

Core SQL

$i''icult to write portable SQL code outsideo' Core SQL



4-7

S+L+C, Statement O"er"iew

SELECT @list o' column e>pressionsA

FROM @list o' tables and oin operationsA

WHERE @list o' logical e>pressions 'or rowsA

GROUP BY @list o' grouping columnsA HAVING @list o' logical e>pressions 'or groupsA

ORDER BY @list o' sorting speci'icationsA

+>pression9 combination o' columns( constants(operators( and 'unctions



4-8

3ni"ersity $atabase



4-9

First S+L+C, +>amples

Example 1

SELECT * FROM Faculty

Example 2 (Access)

SELECT *

FROM Faculty WHERE FacSSN = '!"#$%&('

Example 3

SELECT FacF)+tNa,-. FacLa+tNa,-. FacSalay

FROM Faculty

Example 4

SELECT FacF)+tNa,-. FacLa+tNa,-. FacSalay

FROM Faculty

WHERE FacSalay / 0%%% AND FacRa12 = 'PROF'



4-10

3sing +>pressions

Example 5 (Access)

SELECT FacF)+tNa,-. FacLa+tNa,-. FacC)ty.

FacSalay*$3$ AS I1c-a+-4Salay.

FacH)-Dat-

FROM FacultyWHERE y-a5FacH)-Dat-6 / $&&0

Example 5 (Oracle)

SELECT FacF)+tNa,-. FacLa+tNa,-. FacC)ty.

FacSalay*$3$ AS I1c-a+-4Salay.FacH)-Dat-

FROM Faculty

WHERE t781u,9-5t78c:a5FacH)-Dat-. 'YYYY'66

/ $&&0



4-11

)ne>act 6atching

• Match against a pattern: LIKE peratr

• !se meta characters t speci"# patterns

$ %il&car& (' r )

$ An# single character ( r *)

Example + (Access)

SELECT *

FROM O;;-)1<

WHERE C7u+-N7 LIE 'IS*'

Example + (Oracle)

SELECT *

FROM O;;-)1<

WHERE C7u+-N7 LIE 'IS>'



4-12

3sing $ates

• ,ates are n-m.ers

• ,ate cnstants an& "-nctins are nt stan&ar&

Example / (Access)

SELECT FacF)+tNa,-. FacLa+tNa,-. FacH)-Dat-

FROM Faculty

WHERE FacH)-Dat- BETWEEN ?$@$@$&&&?

AND ?$#@"$@#%%%?

Example / (Oracle)SELECT FacF)+tNa,-. FacLa+tNa,-. FacH)-Dat-

FROM Faculty

WHERE FacH)-Dat- BETWEEN '$a1$&&&'

AND '"$D-c#%%%'



4-13

Other Single ,able +>amples

Example 0: esting "r n-ll al-es

SELECT O;;-N7. C7u+-N7

FROM O;;-)1<

WHERE FacSSN IS NULL AND O;;T-, = 'SUMMER'

AND O;;Y-a = #%%0

Example : Mixing A, an& O

SELECT O;;-N7. C7u+-N7. FacSSN

FROM O;;-)1<WHERE 5O;;T-, = 'FALL' AND O;;Y-a = #%%6

OR 5O;;T-, = 'WINTER' AND O;;Y-a = #%%06



4-14

Join Operator

6ost databases ha"e many tables

Combine tables using the oin operator

Speci'y matching condition Can be any comparison but usually

!5 F5 most common oin condition

*elationship diagram use'ul when combining

tables



4-15

Join +>ample

FacSSN FacName

...:..:.... oe

???:??:???? sue

---:--:---- sara

OfferNo FacSSN

.... ...:..:....

???? ???:??:????

---- ...:..:....

FacSSN FacName OfferNo

...:..:.... oe ....

???:??:???? sue ????

...:..:.... oe ----

Faculty

Offern!

Natural "on of Offern! an#

Faculty



4-16

Cross !roduct Style

• List ta.les in the 6OM cla-se

• List 7in cn&itins in the %8EE cla-se

Example 19 (Access)

SELECT O;;-N7. C7u+-N7. FacF)+tNa,-.

FacLa+tNa,-

FROM O;;-)1<. Faculty

WHERE O;;T-, = 'FALL' AND O;;Y-a = #%%AND FacRa12 = 'ASST' AND C7u+-N7 LIE 'IS*'

AND Faculty3FacSSN = O;;-)1<3FacSSN



4-17

Join Operator Style

• !se IE OI an& O ;e#<r&s

• 6OM cla-se cntains 7in peratins

Example 11 (Access)

SELECT O;;-N7. C7u+-N7. FacF)+tNa,-.

FacLa+tNa,-

FROM O;;-)1< INNER OIN Faculty

ON Faculty3FacSSN = O;;-)1<3FacSSN WHERE O;;T-, = 'FALL' AND O;;Y-a = #%%

AND FacRa12 = 'ASST' AND C7u+-N7 LIE 'IS*'



4-18

2ame Quali'ication

#mbiguous column re'erence 6ore than one table in the Duery contains a

column re'erenced in the Duery

#mbiguity determined by the Duery not thedatabase

3se column name alone i' Duery is notambiguous

Quali'y with table name i' Duery isambiguous

*eadability "ersus writability



4-19

Summariing ,ables

*ow summaries important 'or decision:making

tasks

*ow summary

*esult contains statistical <aggregate= 'unctions Conditions in"ol"e statistical 'unctions

SQL keywords

#ggregate 'unctions in the output list G*O3! B89 summary columns

E#)2G9 summary conditions



4-20

G*O3! B8 +>amples

Example 12: =r-ping n a single cl-mn

SELECT FacRa12. AVG5FacSalay6 AS A<Salay

FROM Faculty

GROUP BY FacRa12

Example 13: < an& gr-p cn&itins

SELECT St4Ma7. AVG5St4GPA6 AS A<Ga

FROM Stu4-1t

WHERE St4Cla++ IN 5'R'. 'SR'6

GROUP BY St4Ma7

HAVING AVG5St4GPA6 / "3$



4-21

SQL Summariation *ules

Columns in S+L+C, and G*O3! B8

S+L+C,9 non aggregate and aggregate

columns

G*O3! B89 list all non aggregate columns

%E+*+ "ersus E#)2G

*ow conditions in %E+*+

Group conditions in E#)2G



4-22

Summariation and Joins

• ><er"-l cm.inatin

• List 7in cn&itins in the %8EE cla-se

Example 14: List the n-m.er " st-&ents enrlle& in each "all 2993

""ering?

SELECT O;;-)1<3O;;-N7.

COUNT5*6 AS Nu,Stu4-1t+

FROM E17ll,-1t. O;;-)1<WHERE O;;-)1<3O;;-N7 = E17ll,-1t3O;;-N7

AND O;;Y-a = #%%0

GROUP BY O;;-)1<3O;;-N7



4-23

Conceptual +"aluation !rocess

F*O6 ,ables9

Cross !roduct and

Join Operations

G*O3!

B8&

*estriction

on %E+*+

Conditions

Sort on

G*O3! B8

Columns

Compute

#ggregates

and *educe

+ach Group

to . *ow

O*$+*

B8&

SortColumns in

O*$+* B8

.

?

-

4

;

8es

2o

8es

2o

Finish

*estriction

on E#)2G

Conditions

7

!roect

Columns in

S+L+C,



4-24

Conceptual +"aluation

Lessons *ow operations be'ore group operations

F*O6 and %E+*+ be'ore G*O3! B8 and

E#)2G

Check row operations 'irst

Grouping occurs only one time

3se small sample tables



4-25

Conceptual +"aluation !roblem

Example 15: List the n-m.er " ""erings ta-ght in 299+ .#

"ac-lt# ran; an& &epartment? Excl-&e cm.inatins " "ac-lt#

ran; an& &epartment <ith less than t< ""erings ta-ght?

SELECT FacRa12. FacD-t.

COUNT5*6 AS Nu,O;;-)1<+

FROM Faculty. O;;-)1<

WHERE O;;-)1<3FacSSN = Faculty3FacSSNAND O;;Y-a = #%%0

GROUP BY FacRa12. FacD-t

HAVING COUNT5*6 / $



4-26

Query Formulation !rocess

>r.lem

@tatement

>r.lem

@tatement

,ata.ase

epresentatin

,ata.ase Lang-age

@tatement



4-27

Critical Questions

%hat tables&

Columns in output

Conditions to test <including oin conditions=

Eow to combine the tables& 3sually oin !5 to F5

6ore comple> ways to combine

)ndi"idual rows or groups o' rows&

#ggregate 'unctions in output

Conditions with aggregate 'unctions



4-28

+''iciency Considerations

Little concern 'or e''iciency

)ntelligent SQL compilers

Correct and non redundant solution

2o e>tra tables

2o unnecessary grouping

3se E#)2G 'or group conditions only

Chapter / pro"ides additional tips 'or

a"oiding ine''icient S+L+C, statements



4-29

#d"anced !roblems

Joining multiple tables

Sel' oins

Grouping a'ter oining multiple tables

,raditional set operators



4-30

Joining ,hree ,ables

+>ample .;9 List Leonard inces teaching schedule in 'all?117H For each course( list the o''ering number( coursenumber( number o' units( days( location( and timeH

SELECT O;;-N7. O;;-)1<3C7u+-N7. O;;Day+.

C+U1)t+. O;;L7cat)71. O;;T),-

FROM Faculty. C7u+-. O;;-)1<

WHERE Faculty3FacSSN = O;;-)1<3FacSSN

AND O;;-)1<3C7u+-N7 = C7u+-3C7u+-N7

AND O;;Y-a = #%% AND O;;T-, = 'FALL'AND FacF)+tNa,- = 'L-71a4'

AND FacLa+tNa,- = 'V)1c-'



4-31

Joining Four ,ables

+>ample .9 List Bob 2orberts course schedule in spring ?11;HFor each course( list the o''ering number( course number( days(location( time( and 'aculty nameH

SELECT O;;-)1<3O;;-N7. O;;-)1<3C7u+-N7.

O;;Day+. O;;L7cat)71. O;;T),-. FacF)+tNa,-. FacLa+tNa,-

FROM Faculty. O;;-)1<. E17ll,-1t. Stu4-1t

WHERE O;;-)1<3O;;-N7 = E17ll,-1t3O;;-N7

AND Stu4-1t3St4SSN = E17ll,-1t3St4SSN

AND Faculty3FacSSN = O;;-)1<3FacSSN

AND O;;Y-a = #%%0 AND O;;T-, = 'SPRING'

AND St4F)+tNa,- = 'BOB'

AND St4La+tNa,- = 'NORBERT'



4-32

Sel':Join

Join a table to itsel' 3sually in"ol"e a sel':re'erencing

relationship

3se'ul to 'ind relationships among rows o'the same table Find subordinates within a preset number o'

le"els

Find subordinates within any number o' le"elsreDuires embedded SQL



4-33

Sel':Join +>ample

+>ample ./9 List 'aculty members who ha"e a highersalary than their super"isorH List the social securitynumber( name( and salary o' the 'aculty and super"isorH

SELECT Su93FacSSN. Su93FacLa+tNa,-. Su93FacSalay. Su3FacSSN.

Su3FacLa+tNa,-. Su3FacSalay

FROM Faculty Su9. Faculty Su

WHERE Su93FacSu-)+7 = Su3FacSSN

AND Su93FacSalay / Su3FacSalay



4-34

6ultiple Joins Between ,ables

+>ample .09 List the names o' 'aculty members and thecourse number 'or which the 'aculty member teaches thesame course number as his or her super"isor in ?11;H

SELECT FacF)+tNa,-. FacLa+tNa,-. O$3C7u+-N7

FROM Faculty. O;;-)1< O$. O;;-)1< O#

WHERE Faculty3FacSSN = O$3FacSSN

AND Faculty3FacSu-)+7 = O#3FacSSNAND O$3O;;Y-a = #%%0 AND O#3O;;Y-a = #%%0

AND O$3C7u+-N7 = O#3C7u+-N7



4-35

6ultiple Column Grouping

+>ample ?19 List the course number( the o''ering number(

and the number o' students enrolledH Only include courses

o''ered in spring ?11;H

SELECT C7u+-N7. E17ll,-1t3O;;-N7.

C7u1t5*6 AS Nu,Stu4-1t+

FROM O;;-)1<. E17ll,-1t

WHERE O;;-)1<3O;;-N7 = E17ll,-1t3O;;-N7

AND O;;Y-a = #%%0 AND O;;T-, = 'SPRING'

GROUP BY E17ll,-1t3O;;-N7. C7u+-N7



4-36

,raditional Set Operators

A !IO

A IE@EB

A MI!@



4-37

3nion Compatibility

*eDuirement 'or the traditional set

operators

Strong reDuirement

Same number o' columns

+ach corresponding column is compatible

!ositional correspondence

#pply to similar tables by remo"ing

columns 'irst



4-38

SQL 32)O2 +>ample

+>ample ?.9 *etrie"e basic data about all uni"ersity people

S+L+C, FacSS2 #S SS2( FacFirst2ame #S First2ame(

FacLast2ame #S Last2ame( FacCity #S City(

FacState #S State

F*O6 Faculty

32)O2

S+L+C, StdSS2 #S SS2( StdFirst2ame #S First2ame( StdLast2ame #S Last2ame( StdCity #S City(

StdState #S State F*O6 Student



4-39

Oracle )2,+*S+C, +>ample

+>ample ??9 Show teaching assistants( 'aculty who arestudentsH Only show the common columns in the resultH

SELECT FacSSN AS SSN. FacF)+tNa,- AS

F)+tNa,-. FacLa+tNa,- AS La+tNa,-.FacC)ty AS C)ty. FacStat- AS Stat-

FROM Faculty

INTERSECT

SELECT St4SSN AS SSN. St4F)+tNa,- AS F)+tNa,-. St4La+tNa,- AS La+tNa,-.

St4C)ty AS C)ty. St4Stat- AS Stat-

FROM Stu4-1t



4-40

Oracle 6)23S +>ample

+>ample ?-9 Show 'aculty who are not students <pure'aculty=H Only show the common columns in the resultH

SELECT FacSSN AS SSN. FacF)+tNa,- AS

F)+tNa,-. FacLa+tNa,- AS La+tNa,-.FacC)ty AS C)ty. FacStat- AS Stat-

FROM Faculty

MINUS

SELECT St4SSN AS SSN. St4F)+tNa,- AS F)+tNa,-. St4La+tNa,- AS La+tNa,-.

St4C)ty AS C)ty. St4Stat- AS Stat-

FROM Stu4-1t



4-41

$ata 6anipulation Statements

)2S+*,9 adds one or more rows

3!$#,+9 modi'ies one or more rows

$+L+,+9 remo"es one or more rows

3se S+L+C, statement to )2S+*,

multiple rows

3!$#,+ and $+L+,+ can use a %E+*+clause

2ot as widely used as S+L+C, statement



4-42

)2S+*, +>ample

+>ample ?49 )nsert a row into the Student table supplying

"alues 'or all columnsH

INSERT INTO Stu4-1t5St4SSN. St4F)+tNa,-. St4La+tNa,-.

St4C)ty. St4Stat-. St4). St4Cla++.

St4Ma7. St4GPA6

VALUES5'&&&&&&&&&'.'OE'.'STUDENT'.'SEATAC'.

'WA'.'&%!#$$#$'.'FR'.'IS'. %3%6



4-43

3!$#,+ +>ample

+>ample ?79 Change the maor and class o'Eomer %ellsH

UPDATE Stu4-1tSET St4Ma7 = 'ACCT'.

St4Cla++ = 'SO'

WHERE St4F)+tNa,- = 'HOMER'AND St4La+tNa,- = 'WELLS'



4-44

$+L+,+ +>ample

+>ample ?;9 $elete all )S maors who are seniorsH

DELETE FROM Stu4-1t

WHERE St4Ma7 = 'IS'

AND St4Cla++ = 'SR'



Summary

SQL is a broad language

S+L+C, statement is comple>

3se problem sol"ing guidelines

Lots o' practice to master Duery

'ormulation and SQL

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