1. Chapter Nine Data Manipulation Language (DML) Functions
Objectives
Single Row functions
Character functions
Number functions
Date functions
COSC 640 Chapter 9

2. Functions
Introduction
Types of functions
Single row
Multiple rows

3. Single Row Functions: FACTS: Act on each row Return one result per row
May modify the data type
Can be nested

4. Single Row Functions
Character
Number
Date
Conversion
General

5. Character Manipulation:
LOWER(Col | Exp)
LOWER(‘Database course’)
UPPER (Col | Exp)
UPPER (‘Database course’)
INITCAP (Col | Exp)
INITCAP (‘Database course’)

6. 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,’.’)

7. Character Manipulation
LENGTH(Col | Exp)
LENGTH(‘this is it’)
CHR(integer)
CHR(97)
INSTR(‘Computer’,’m’)

8. List(Characters): Example: SELECT LOWER(name),
UPPER(major), LENGTH(name)
FROM student;
SELECT CONCAT(Name , Address) , GPA
FROM Student;
SELECT Name || ‘--->‘ || Address , GPA

9. List(Characters): SELECT RPAD (Name, 40, ‘.’), GPA FROM Student;
JOHN
MARY
SELECT RPAD (Name, 20), GPA
MARY
MOHAMMAD 3.3
SELECT LPAD (Name, 20), GPA
MARY 3.2
MOHAMMAD 3.3

10. List(Characters): RTRIM(Col) RTRIM (Name) RTRIM (Name, ‘.’)
LTRIM (Name, ‘ABC’)
LTRIM ( RTRIM( Name, ‘.’ ), ‘A’)
From Student;

11. List(Characters): SELECT Name FROM Student
WHERE LENGTH(Address)<20;
SELECT Name, SUBSTR (SSN, 5 ,2)
FROM Student;
SELECT Name, SUBSTR (SSN,5)

12. List(Characters): SELECT RPAD (INITCAP(LOWER(Name)),70,’.’),
SUBSTR (SSN,5)
FROM Student;
SELECT Name
FROM Student
WHERE SUBSTR (SSN,5,2)=’80’;
SELECT Name, SUBSTR (SSN,-4)
FROM Student;

13. List(Characters): ------------------------------------------------
SELECT Name, INSTR (Name,’R’)
FROM Student;  
MARY 3
JOHN 0
ROBIN 1
SELECT Name, INSTR (Name,’R’,1,2)
SELECT Name, INSTR(Address,’FROSTBURG’)
FROM Student;

14. List(Characters): Character Manipulations
REPLACE(string, searchSt [,replace])
REPLACE(address,’21532’, ‘21211’)
TRANSLATE (string, fromSt, toSt)
TRANSLATE(‘ ’, ‘123’, ‘999’)
ASCII(string)
ASCII(‘A’)

15. List(Characters): Character Manipulations SOUNDEX SELECT name, GPA
FROM student
WHERE
SOUNDEX (name)=SOUNDEX(‘LAVALE’);

16. Character Manipulation
New Functions:
REGEXP_SUBSTR
REGEXP_INSTR
REGEXP_LIKE
REGEXP_REPLACE

17. LIST(Numbers) ROUND (value, precision) TRUNC(value, precision)
POWER(value,exponent)
POWER(3,2) 
MOD(value1, value2)
MOD(900,400)

18. LIST(Numbers) SELECT ROUND(Salary,1) FROM Faculty;
SELECT TRUNC( ,2),
FROM DUAL;
TRUNC( );
TRUNC( ,-2);

19. DATE:
Date is stored in an internal numeric format: century, year, month, day, hours, minutes, second
Default date is ‘DD-MON-YY’
SYSDATE
CURRENT_DATE
STSTIMESTAMP
25-OCT PM

20. DATE: Example: List the ages of students SELECT name, SYSDATE - B_Date
SELECT name, SYSDATE - B_Date
FROM student;

21. Date
Date + number
Date – number
Date – date
Date + number/24

22. DATE: MONTHS_BETWEEN(day1,day2)
SELECT name, MONTHS_BETWEEN(SYSDATE , B_Date) age_in_month
FROM Student;

23. DATE: ADD_MONTHS (date,n) SELECT name, ADD_MONTHS(B_Date,5) age
FROM Student;
SELECT name, ADD_MONTHS(B_Date,-15) age

24. DATE: ROUND(date [,fmt]) SELECT name, ROUND (B_Date,’MONTH’)
SELECT name,
ROUND (B_Date,’MONTH’)
FROM Student;
SELECT name, ROUND(B_Date,’YEAR’)

25. DATE: ROUND(date [,fmt]) SELECT ’25-OCT-04’ - ROUND (SYSDATE)
SELECT ’25-OCT-04’ - ROUND (SYSDATE)
FROM DOAL;
SELECT name, ROUND(B_Date,’YEAR’)
FROM Student;

26. DATE: NEXT_DAY SELECT cycledate FROM paydate;
SELECT NEXT_DAY(cycledate, ‘FRIDAY’)

27. DATE: LAST_DAY (date) SELECT LAST_DAY (SYSDATE) “Last”,
SYSDATE, LAST_DAY (SYSDATE) – SYSDATE “Left”
FROM DUAL;
Last SYSDATE Left
31-MAY MAY

28. Conversion Function: Implicit conversion (Automatic):
CHAR or VARCHAR2 to NUMBER
CHAR or VARCHAR2 to DATE
NUMBER to VARCHAR2
DATE to VARCHAR2

29. Conversion Function: Explicit datatype conversion:
TO_CHAR (NUMBER [,‘fmt’] )
TO_CHAR (DATE [,‘fmt’] )
TO_DATE (CHAR [,‘fmt’] )
TO_NUMBER (CHAR [,‘fmt’] )

30. Conversion Function: SELECT TO_CHAR(b_date,’MM/YY’) FROM student;
Format:
YYYY
YYY YY RR
YEAR MM
MONTH DD DY
DAY
HH HH12 HH24 MI SS

31. Conversion Function: EXTRACT (YEAR FROM B_Date)
MONTH
DAY
HOUR
MINUTE
SECOND
SELECT EXTRACT (YEAR FROM DATE ‘ ’)
FROM DUAL;
SELECT EXTRACT (YEAR FROM TO_DATE
(B_Date, ‘DD-MON-YY’)
FROM Student;

32. Conversion Function: SELECT SUBSTR(TO_CHAR(111223333),1,3) ||‘-’ ||
FROM Student;

33. Conversion Function: SELECT SUBSTR(ssn,1,3) || ‘-’ || SUBSTR(ssn,4,2)
FROM Student;

34. CAST CAST (expression) AS (Type); CAST (B_Date AS CHAR);
CHAR NUMBER DATE ROW ROWID
VARCHAR TIMESTAMP
X X X X X
X X
X X
X X
X X
CAST (B_Date AS CHAR);

35. NULLIF NULLIF (Exp1, Exp2) IF Exp1 = Exp2 THEN RETURN NULL ELSE RETURN
SELECT Name, NULLIF (a.major, b.major)
“oldMajor”
FROM Student a, StudentHistory b
WHERE a.ID = b.ID;

36. NVL NVL (Exp1,Exp2) SELECT Name, NVL FROM Sales;
(TO_CHAR (Commission_pct, ‘Not Applicable’)) commission
FROM Sales;

37. NVL2 NVL2 (Exp1, Exp2, Exp3) SELECT Name,
NVL2 (Commission_pct, Salary + Salary * Commission_pct, Salary)
FROM Employee;

38. COALESCE COALESCE (exp_List)
Return the first non_null expression in the expression list:
COALESCE ( , Address, Phone_#, Phone_W)
SELECT Product_ID, Product_Name, List_Price, Min_Price, COALESCE (List_Price, Min_Price, 10) ”Sale Price”
FROM Product;

39. Use of DECODE: DECODE: DECODE (col/exp, compare1, result1
[,default] )
SELECT name, salary,
DECODE (Dept, ‘COSC’, salary*2.2,
‘MATH’, salary*1.2,
‘ART’, salary*0.2,
salary)
FROM Faculty;
COSC 640 Chapter 9