sql03(m) - 3 Single-Row Functions Objectives After...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 3 Single-Row Functions Objectives After completing this lesson, you should be able to do the following: Describe various types of functions available in SQL Use character, number, and date functions in SELECT statements Describe the use of conversion functions 3-2 SQL Functions Input arg 1 arg 2 Output Function Function performs action Result value arg n 3-3 Two Types of SQL Functions Functions Single-row functions Multiple-row functions 3-4 Single-Row Functions Manipulate data items Accept arguments and return one value Act on each row returned Return one result per row May modify the datatype Can be nested function_name (column|expression, [arg1, arg2,...]) 3-5 Single-Row Functions Character General Single-row functions Number Conversion Date 3-6 Character Functions Character functions Case conversion functions LOWER UPPER INITCAP Character manipulation functions CONCAT SUBSTR LENGTH INSTR LPAD | RPAD TRIM 3-7 REPLACE Case Conversion Functions Convert case for character strings Function UPPER('SQL Course') Result SQL COURSE LOWER('SQL Course') sql course INITCAP('SQLCourse') Sql Course 3-8 Using Case Conversion Functions Display the employee number, name, and department number for employee Blake. SQL> SELECT empno, ename, deptno 2 FROM emp 3 WHERE ename = 'blake'; no rows selected SQL> SELECT 2 FROM 3 WHERE empno, ename, deptno emp LOWER(ename) = 'blake'; EMPNO ENAME DEPTNO --------- ---------- --------7698 BLAKE 30 3-9 Character Manipulation Functions Manipulate character strings Function SUBSTR('String',1,3) LENGTH('String') INSTR('String', 'r') LPAD(sal,10,'*') Str 6 3 ******5000 Result CONCAT('Good', 'String') GoodString 3-10 Using the Character Manipulation Functions SQL> SELECT ename, CONCAT (ename, job), LENGTH(ename), 2 INSTR(ename, 'A') 3 FROM emp SUBSTR(job,1,5) = 'SALES'; 4 WHERE ENAME ---------MARTIN ALLEN TURNER WARD CONCAT(ENAME,JOB) LENGTH(ENAME) INSTR(ENAME,'A') ------------------- ------------- ---------------MARTINSALESMAN 6 2 ALLENSALESMAN 5 1 TURNERSALESMAN 6 0 WARDSALESMAN 4 2 3-11 Number Functions ROUND: Rounds value to specified decimal 45.93 Truncates value to specified decimal 45.92 ROUND(45.926, 2) TRUNC: TRUNC(45.926, 2) MOD: Returns remainder of division 100 MOD(1600, 300) 3-12 Using the ROUND Function SQL> SELECT ROUND(45.923,2), ROUND(45.923,0), 2 ROUND(45.923,-1) 3 FROM DUAL; ROUND(45.923,2) ROUND(45.923,0) ROUND(45.923,-1) --------------- -------------- ----------------45.92 46 50 3-13 Using the TRUNC Function SQL> SELECT TRUNC(45.923,2), TRUNC(45.923), 2 TRUNC(45.923,-1) 3 FROM DUAL; TRUNC(45.923,2) TRUNC(45.923) TRUNC(45.923,-1) --------------- ------------- --------------45.92 45 40 3-14 Using the MOD Function Calculate the remainder of the ratio of salary to commission for all employees whose job title is a salesman. SQL> SELECT 2 FROM 3 WHERE ename, sal, comm, MOD(sal, comm) emp job = 'SALESMAN'; ENAME SAL COMM MOD(SAL,COMM) ---------- --------- --------- ------------MARTIN 1250 1400 1250 ALLEN 1600 300 100 TURNER 1500 0 1500 WARD 1250 500 250 3-15 Working with Dates Oracle stores dates in an internal numeric format: Century, year, month, day, hours, minutes, seconds. The default date format is DD-MON-YY. SYSDATE is a function returning date and time. DUAL is a dummy table used to view SYSDATE. 3-16 Working with Dates SYSDATE is a function that returns: Date Time 3-17 Arithmetic with Dates Add or subtract a number to or from a date for a resultant date value. Subtract two dates to find the number of days between those dates. Add hours to a date by dividing the number of hours by 24. 3-18 Using Arithmetic Operators with Dates SQL> SELECT ename, (SYSDATE-hiredate)/7 WEEKS 2 FROM emp 3 WHERE deptno = 10; ENAME ---------KING CLARK MILLER WEEKS --------830.93709 853.93709 821.36566 3-19 Date Functions FUNCTION MONTHS_BETWEEN ADD_MONTHS NEXT_DAY LAST_DAY ROUND TRUNC 3-20 DESCRIPTION Number of months between two dates Add calendar months to date Next day of the date specified Last day of the month Round date Truncate date Using Date Functions MONTHS_BETWEEN ('01-SEP-95','11-JAN-94') 19.6774194 ADD_MONTHS ('11-JAN-94',6) '11-JUL-94' NEXT_DAY ('01-SEP-95','FRIDAY') '08-SEP-95' LAST_DAY('01-SEP-95') 3-21 '30-SEP-95' Using Date Functions ROUND('25-JUL-95','MONTH') ROUND('25-JUL-95','YEAR') TRUNC('25-JUL-95','MONTH') TRUNC('25-JUL-95','YEAR') 01-AUG-95 01-JAN-96 01-JUL-95 01-JAN-95 3-22 Conversion Functions Datatype conversion Implicit datatype conversion Explicit datatype conversion 3-23 Implicit Datatype Conversion For assignments, Oracle can automatically convert From VARCHAR2 or CHAR VARCHAR2 or CHAR NUMBER DATE 3-24 To NUMBER DATE VARCHAR2 VARCHAR2 Implicit Datatype Conversion For expression evaluation, Oracle can automatically convert From VARCHAR2 or CHAR VARCHAR2 or CHAR To NUMBER DATE 3-25 Explicit Datatype Conversion TO_NUMBER TO_DATE NUMBER CHARACTER DATE TO_CHAR TO_CHAR 3-26 TO_CHAR Function with Dates TO_CHAR(date, 'fmt') The format model: Must be enclosed in single quotation marks and is case sensitive Can include any valid date format element Has an fm element to remove padded blanks or suppress leading zeros Is separated from the date value by a comma 3-27 Date Format Model Elements YYYY YEAR MM MONTH DY DAY 3-28 Full year in numbers Year spelled out 2-digit value for month Full name of the month 3-letter abbreviation of the day of the week Full name of the day Date Format Model Elements Time elements format the time portion of the date. HH24:MI:SS AM 15:45:32 PM Add character strings by enclosing them in double quotation marks. DD "of" MONTH ddspth 12 of OCTOBER fourteenth Number suffixes spell out numbers. 3-29 Using TO_CHAR Function with Dates SQL> SELECT ename, 2 TO_CHAR(hiredate, 'fmDD Month YYYY') HIREDATE 3 FROM emp; ENAME HIREDATE ---------- ----------------KING 17 November 1981 BLAKE 1 May 1981 CLARK 9 June 1981 JONES 2 April 1981 MARTIN 28 September 1981 ALLEN 20 February 1981 ... 14 rows selected. 3-30 TO_CHAR Function with Numbers TO_CHAR(number, 'fmt') Use these formats with the TO_CHAR function to display a number value as a character. 9 0 $ L . , 3-31 Represents a number Forces a zero to be displayed Places a floating dollar sign Uses the floating local currency symbol Prints a decimal point Prints a thousand indicator Using TO_CHAR Function with Numbers SQL> SELECT 2 FROM 3 WHERE TO_CHAR(sal,'$99,999') SALARY emp ename = 'SCOTT'; SALARY -------$3,000 3-32 TO_NUMBER and TO_DATE Functions Convert a character string to a number format using the TO_NUMBER function TO_NUMBER(char) Convert a character string to a date format using the TO_DATE function TO_DATE(char[, 'fmt']) 3-33 RR Date Format Current Year 1995 1995 2001 2001 Specified Date 27-OCT-95 27-OCT-17 27-OCT-17 27-OCT-95 RR Format 1995 2017 2017 1995 YY Format 1995 1917 2017 2095 If the specified two-digit year is 0-49 If two digits of the current year are 0-49 The return date is in the current century. The return date is in the century after the current one. 50-99 The return date is in the century before the current one. The return date is in the current century. 50-99 3-34 NVL Function Converts null to an actual value Datatypes that can be used are date, character, and number. Datatypes must match NVL(comm,0) NVL(hiredate,'01-JAN-97') NVL(job,'No Job Yet') 3-35 Using the NVL Function SQL> SELECT ename, sal, comm, (sal*12)+NVL(comm,0) 2 FROM emp; ENAME SAL COMM (SAL*12)+NVL(COMM,0) ---------- --------- --------- -------------------KING 5000 60000 BLAKE 2850 34200 CLARK 2450 29400 JONES 2975 35700 MARTIN 1250 1400 16400 ALLEN 1600 300 19500 ... 14 rows selected. 3-36 Using NVL2 Function NVL2(expr1,expr2,expr3) If expr1 is not null NVL2 returns expr2. If expr1 is null NVL2 returns expr3. SELECT last_name, salary,commission_pct, NVL2(commission_pct, 'SAL+COMM', 'SAL') income FROM employees WHERE department_id IN (50,80); 3-37 Using the NULLIF Function NULLIF(expr1,expr2) Compares two expressions and returns null if they are equal SELECT first_name,LENGTH(first_name) exp1 last_name, LENGTH(last_name) exp2, NULLIF(LENGTH(first_name), LENGTH (last_name)) result FROM employees; 3-38 Conditional Expressions Provide the use of IF-THEN-ELSE logic with in a SQL statement Use two methods: CASE expression DECODE function 3-39 The CASE Expression Facilitates conditional inquires by doing the work of an IF-THEN-ELSE statement: CASE expr WHEN comparison_expr1 THEN return_expr1 [WHEN comparison_expr2 THEN return_expr2 ELSE else_expr] END 3-40 DECODE Function Facilitates conditional inquiries by doing the work of a CASE or IF-THEN-ELSE statement DECODE(col/expression, search1, result1 [, search2, result2,...,] [, default]) 3-41 Using the DECODE Function SQL> SELECT job, sal, 2 DECODE(job, 'ANALYST', SAL*1.1, 3 'CLERK', SAL*1.15, 4 'MANAGER', SAL*1.20, 5 SAL) 6 REVISED_SALARY 7 FROM emp; JOB SAL REVISED_SALARY --------- --------- -------------PRESIDENT 5000 5000 MANAGER 2850 3420 MANAGER 2450 2940 ... 14 rows selected. 3-42 Nesting Functions Single-row functions can be nested to any level. Nested functions are evaluated from deepest level to the least deep level. F3(F2(F1(col,arg1),arg2),arg3) Step 1 = Result 1 Step 2 = Result 2 Step 3 = Result 3 3-43 Nesting Functions SQL> SELECT 2 3 FROM 4 WHERE ename, NVL(TO_CHAR(mgr),'No Manager') emp mgr IS NULL; ENAME NVL(TO_CHAR(MGR),'NOMANAGER') ---------- ----------------------------KING No Manager 3-44 Summary Use functions to: Perform calculations on data Modify individual data items Manipulate output for groups of rows Alter date formats for display Convert column datatypes 3-45 ...
View Full Document

This note was uploaded on 06/27/2011 for the course COMPUTER S 133 taught by Professor Andrewstrauss during the Spring '11 term at Bucks Community College.

Page1 / 45

sql03(m) - 3 Single-Row Functions Objectives After...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online