SQL. - single row functions - Database Design ( 데이터베이스설계 ) JUNG, Ki-Hyun ( 정기현 )

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1 SQL Database Design ( 데이터베이스설계 ) - single row functions - JUNG, Ki-Hyun ( 정기현 ) 1

2 SQL Functions Input Function Output Function performs action that defined already before execution 2

3 Two Types of SQL Functions Functions Single-row Function Multiple-row Function... 3

4 Single-Row Functions 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 data type Can be nested Accept arguments which can be a column or an expression 4 Function_name [(argument1, argument2, )]

5 Kinds of Single-Row Functions Single-row Functions Character Number Date Conversion General 5

6 Character Functions Character functions Case-manipulation Functions LOWER, UPPER, INITCAP Character-manipulation Functions CONCAT, SUBSTR, LENGTH, INSTR LPAD, RPAD, TRIM, REPLACE 6

7 Case Manipulation Functions These functions convert case for character strings Function LOWER( SQL course ) UPPER( SQL course ) INITCAP( SQL course ) Result sql course SQL COURSE Sql Course 7

8 Using Case Manipulation Functions Display the employee number, name, and department number for employee king SELECT empno, ename, deptno FROM emp WHERE ename = king ; SELECT empno, ename, deptno FROM emp WHERE LOWER(ename) = king ; 8 Not supported by MySQL

9 Character Manipulation Functions These functions manipulate character strings 9 Function Result CONCAT( Hello, World ) HelloWorld SUBSTR( HelloWorld, 1, 5) Hello LENGTH( HelloWorld ) 10 INSTR( HelloWorld, W ) 6 LPAD(salary, 10, * ) *****24000 RPAD(salary, 10, * ) 24000***** TRIM( H FROM HelloWorld ) elloworld

10 Using the Character Manipulation Functions SELECT empno, CONCAT(ename, job) NAME, LENGTH(ename), INSTR(ename, a ) Contains a? FROM emp WHERE substr(job, 2, 3) = ANA ; 10

11 Number Functions ROUND Rounds value to specified decimal ROUND(45.926, 2) -> TRUNC Truncates value to specified decimal TRUNC(45.926, 2) -> MOD Returns remainder of division MOD(1600, 300) ->

12 Using the ROUND Function SELECT ROUND(45.923, 2), ROUND(45.923, 0), ROUND(45.923, -1) FROM DUAL; DUAL is a dummy table you can use to view results from functions and calculations 12

13 Using the TRUNC and MOD Function SELECT TRUNC(45.923, 2), TRUNC(45.923), TRUNC(45.923, -2) FROM DUAL; Calculate the remainder of a salary after it is divided by 5000 for all employee whose job title is sales representative SELECT ename, sal, MOD(sal, 5000) FROM emp WHERE job = MANAGER ; 13

14 Working with Dates SELECT hiredate FROM emp WHERE ename LIKE A% ; The default date display format is DD-MON-RR (ORACLE) YYYY-MM-DD (MySQL) a function that returns Date and Time SYSDATE (ORACLE) NOW() (MySQL) cf. CURDATE() SELECT ename, (now() hiredate) / 7 AS WEEKS FROM emp 14 WHERE deptno = 30;

15 MySQL Date Format select DATE_FORMAT(hiredate, %M %d, %Y ) from emp; 15 %Y : Four-digit year %y : Two-digit year %M : complete month name %b : month name, initial three letters %m : Two-digit month of year (01 12) %c : month of year (1 12) %d : Two-digit day of month (01 31) %e : Day of month (1 31) %r : 12-hour time with AM or PM suffix %T : 24-hour time %H : Two-digit hour %i : Two-digit minute %s : Two-digit second %% : literal %

16 MySQL Date Function select YEAR(hiredate), DAYNAME(hiredate) from emp; YEAR() MONTH() MONTHNAME() DAYOFMONTH() DAYNAME() DAYOFWEEK() WEEKDAY() DAYOFYEAR() HOUR() MINUTE() SECOND() 16

17 ORACLE Data Type Conversion TO_NUMBER TO_CHAR NUMBER CHARACTER DATE TO_CHAR TO_DATE 17

18 Using the TO_CHAR Function with Dates ORACLE TO_CHAR(date, format_model ) format_model 18 YYYY Full year in numbers YEAR Year spelled out MM Two-digit value for month MONTH Full name of the month MON Three-letter abbreviation of the month DY Three-letter abbreviation of the day of the week DAY Full name of the day of the week DD Numeric day of the month

19 Using the TO_CHAR Function with Dates ORACLE SELECT last_name, TO_CHAR(hire_date, fmdd Month YYYY ) AS HIREDATE FROM employees; fm Element to remove padded blanks or suppress leading zeros 19

20 Using the TO_CHAR Function with Numbers ORACLE TO_CHAR(number, format_model ) format_model 9 Represents a number 0 Forces a zero to be displayed $ Places a floating dollar sign L Uses the floating local currency symbol. Prints a decimal point, Prints a thousand indicator 20

21 Using the TO_CHAR Function with Numbers ORACLE SELECT TO_CHAR(salary, $99, ) SALARY FROM employees WHERE last_name = Ernst ; 21

22 ORACLE NVL Function Converts a null to an actual value Data types that can be used are date, character, and number Data types must match NVL(comm, 0) NVL(hiredate, 01-JAN-97 ) NVL(job, No Job Yet ) 22 MySQL : IFNULL( )

23 Using the NVL Function ORACLE SELECT ename, sal, NVL(comm, 0), (sal*12) + (sal*12* NVL(comm, 0)) AnnalSalary FROM emp; 23

24 Summary You should have learned how to Perform calculations on data using functions Modify individual data items using functions Manipulate output for groups of rows using functions Alter date formats for display using functions Convert column data types using functions Use NVL functions 24

GIFT Department of Computing Science. [Spring 2016] CS-217: Database Systems. Lab-3 Manual. Single Row Functions in SQL

GIFT Department of Computing Science [Spring 2016] CS-217: Database Systems Lab-3 Manual Single Row Functions in SQL V3.0 4/26/2016 Introduction to Lab-3 Functions make the basic query block more powerful,