chapter six data manipulation language (dml) functions objectives single row functions character...
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Chapter SixData Manipulation Language (DML)Functions
Objectives Single Row functions Character functions Number functions Date functions
Single Row Functions:
FACTS: Act on each row Return one result per row May modify the data type returned type Can be nested
5
Character Manipulation: LOWER(Col | Exp)
LOWER(‘Database course’)
UPPER (Col | Exp)UPPER (‘Database course’)
INITCAP (Col | Exp)INITCAP (‘Database course’)
6
Practice:
Display last name and first name of customers. Last name in upper case. First character of each first name in upper case, the rest in lower case.
Example:
SMITH Lori
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Character Manipulation CONCAT (Col1 | Exp1, Col2 | Exp2)
CONCAT(‘This ‘,’that’)
SUBSTR(Col | Exp,n,[m])SUBSTR(‘This is it’,2,5)
LPAD(Col | Exp,n,’string’)LPAD(name,9,’.’)
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Character Manipulation LENGTH(Col | Exp)
LENGTH(‘this is it’)
CHR(integer)CHR(97)
INSTR(‘Computer’,’m’)
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List(Characters): Example:
SELECT LOWER(name), UPPER(major), LENGTH(name)
FROM student;
SELECT CONCAT(Name , Address) , GPAFROM Student;
SELECT Name || ‘--->‘ || Address , GPA
FROM Student;
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List(Characters): SELECT RPAD (Name, 40, ‘.’), GPA
FROM Student;JOHN............... 3.1MARY ............. 3.2
SELECT RPAD (Name, 20), GPAFROM Student;
MARY 3.2 MOHAMMAD 3.3
SELECT LPAD (Name, 20), GPAFROM Student;
MARY 3.2 MOHAMMAD 3.3
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Practice:
Display the last name and address of each customer together. In the next column display customer phone number.
SMITH 11 MAIN ST FROSTBURG MD……..301 689 1111
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List(Characters): RTRIM(Col)
RTRIM (Name)RTRIM (Name, ‘.’)LTRIM (Name, ‘ABC’)
LTRIM ( RTRIM( Name, ‘.’ ), ‘a’)From Student;
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Practice:
Customer phone number is stored as: -301-689-1111:
Part 1- We would like to delete the first dash and the last colon from the phone numbers:
-301-689-1111:Part 2- Remove all dashes and colon
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List(Characters): SELECT Name
FROM StudentWHERE LENGTH(Address)<20;
SELECT Name, SUBSTR (SSN, 5 ,2)
FROM Student;
SELECT Name, SUBSTR (SSN,5)FROM Student;
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List(Characters): SELECT RPAD
(INITCAP(LOWER(Name)),70,’.’), SUBSTR (SSN,5)
FROM Student;
SELECT NameFROM StudentWHERE SUBSTR (SSN,5,2)=’80’;
SELECT Name, SUBSTR (SSN,-4)FROM Student;
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Practice:
Display the 10 characters from OrderPart description starting at location 6.
Example:Door Replacement Handle
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List(Characters): SELECT Name, INSTR (Name,’r’)
FROMStudent; ------------------------------------------------
MARY 3JOHN 0ROBIN 1
SELECT Name, INSTR (Name,’r’,1,2)FROMStudent;
SELECT Name, INSTR(Address,’Frostburg’)FROMStudent;
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Practice:
We would like to switch the position of last name with the first name. Assume the attribute name consists of both first and last names with a blank character in between.
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LIST(Numbers) ROUND (value, precision)
ROUND(234.1161,2)
TRUNC(value, precision)TRUNC(234.1161,2)
POWER(value,exponent)POWER(3,2)
MOD(value1, value2)MOD(900,400)
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LIST(Numbers) SELECT ROUND(Salary,1)
FROM Faculty;
SELECT TRUNC(234.111,2), FROM DUAL;
TRUNC(234.567);TRUNC(234.5678,-2);
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DATE: Date is stored in an internal numeric
format: century, year, month, day, hours, minutes, second
Default date is DD-MON-YY
SYSDATE
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DATE: MONTHS_BETWEEN(day1,day2)
SELECT name, MONTHS_BETWEEN(SYSDATE , B_Date)
age_in_month
FROM Student;
27
DATE: ROUND(date [,fmt]) SELECT name, ROUND
(B_Date,’MONTH’)FROM Student;
SELECT name, ROUND(B_Date,’YEAR’)FROM Student;
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Conversion Function:
Implicit conversion (Automatic):
CHAR or VARCHAR2 to NUMBER CHAR or VARCHAR2 to DATE NUMBER to VARCHAR2 DATE to VARCHAR2
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Conversion Function:
Explicit datatype conversion:
TO_CHAR (NUMBER [,‘fmt’] ) TO_CHAR (DATE [,‘fmt’] ) TO_DATE (CHAR [,‘fmt’] ) TO_NUMBER (CHAR [,‘fmt’] )
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Conversion Function:
SELECT TO_CHAR(b_date,’MM/YY’)FROM student;
Format: YYYY YEAR MM MONTH DY DAY
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Conversion Function:
SELECTSUBSTR(TO_CHAR(111223333),1,3)
||‘-’ || SUBSTR
(TO_CHAR(111223333),4,2) || ‘-’ ||SUBSTR(TO_CHAR(111223333),6)
FROM Student;
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