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

Functions Introduction Types of functions Single row Multiple rows

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

Single Row Functions Character Number Date Conversion General

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

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,’.’)

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

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

List(Characters): SELECT RPAD (Name, 40, ‘.’), GPA FROM Student; JOHN............... 3.1 MARY ............. 3.2 SELECT RPAD (Name, 20), GPA MARY 3.2 MOHAMMAD 3.3 SELECT LPAD (Name, 20), GPA MARY 3.2 MOHAMMAD 3.3

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

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

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;

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;

List(Characters): Character Manipulations REPLACE(string, searchSt [,replace]) REPLACE(address,’21532’, ‘21211’) TRANSLATE (string, fromSt, toSt) TRANSLATE(‘12345678’, ‘123’, ‘999’) ASCII(string) ASCII(‘A’)

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

Character Manipulation New Functions: REGEXP_SUBSTR REGEXP_INSTR REGEXP_LIKE REGEXP_REPLACE

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

LIST(Numbers) SELECT ROUND(Salary,1) FROM Faculty; SELECT TRUNC(234.111,2), FROM DUAL; TRUNC(234.567); TRUNC(234.5678,-2);

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-04 04.15.31.652000 PM

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

Date Date + number Date – number Date – date Date + number/24

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

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

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

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;

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

DATE: LAST_DAY (date) SELECT LAST_DAY (SYSDATE) “Last”, SYSDATE, LAST_DAY (SYSDATE) – SYSDATE “Left” FROM DUAL; Last SYSDATE Left -------------------------------------------------------- 31-MAY-05 28-MAY-05 4

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

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

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

Conversion Function: EXTRACT (YEAR FROM B_Date) MONTH DAY HOUR MINUTE SECOND SELECT EXTRACT (YEAR FROM DATE ‘1999-01-08’) FROM DUAL; --1999 SELECT EXTRACT (YEAR FROM TO_DATE (B_Date, ‘DD-MON-YY’) FROM Student;

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

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

CAST CAST (expression) AS (Type); CAST (B_Date AS CHAR); CHAR NUMBER DATE ROW ROWID VARCHAR2 TIMESTAMP 1 X X X X X 2 X X 3 X X 4 X X 5 X X CAST (B_Date AS CHAR);

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;

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

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

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

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