3 Using SingleRow Functions to Customize Output Copyright

Practice • Display the data for those employees whose salary grater than number that

Single-Row Functions Character Single-row functions General Conversion 3 -3 Number Date Copyright © 2004,

Working with Dates • • The Oracle database stores dates in an internal numeric

Working with Dates SYSDATE is a function that returns: • • 3 -5 Date

Arithmetic with Dates • • • 3 -6 Add or subtract a number to

Using Arithmetic Operators with Dates Display the last name and the number of weeks

Exercise on Arithmetic with Dates Display the name and hire date of employees whose

Date Functions 3 -9 Function MONTHS_BETWEEN Result ADD_MONTHS Add calendar months to date NEXT_DAY

Using Date Functions Function Result MONTHS_BETWEEN (date 1, date 2) MONTHS_BETWEEN('01 -SEP-95', '11 -JAN-94')

Using Date Functions NEXT_DAY (date, day(‘string or value’)) NEXT_DAY ('01 -SEP-95', 'FRIDAY') '08 -SEP-95'

Using Date Functions Assume SYSDATE = '25 -JUL-03': 3 -12 Function ROUND(SYSDATE, 'MONTH') Result

Practice 3: Overview of Part 1 This practice covers the following topics: • Writing

Conversion Functions Data type conversion Implicit data type conversion 3 -14 Explicit data type

Implicit Data Type Conversion For assignments, the Oracle server can automatically convert the following:

Implicit Data Type Conversion For expression evaluation, the Oracle Server can automatically convert the

Explicit Data Type Conversion TO_NUMBER CHARACTER TO_CHAR 3 -17 TO_DATE TO_CHAR Copyright © 2004,

Using the TO_CHAR Function with Dates TO_CHAR(date, 'format_model') The format model: • Must be

Elements of the Date Format Model 3 -19 Element YYYY Result YEAR Year spelled

Elements of the Date Format Model • Time elements format the time portion of

Using the TO_CHAR Function with Dates SELECT last_name, TO_CHAR(hire_date, 'fm. DD Month YYYY') AS

Using the TO_CHAR Function with Numbers TO_CHAR(number, 'format_model') These are some of the format

Using the TO_CHAR Function with Numbers SELECT TO_CHAR(salary, '$99, 999. 00') SALARY FROM employees

Using the TO_NUMBER and TO_DATE Functions • Convert a character string to a number

General Functions NVL Function Converts a null value to an actual value: • Data

Using the NVL Function 1 SELECT last_name, salary, NVL(commission_pct, 0), (salary*12) + (salary*12*NVL(commission_pct, 0))

Conditional Expressions • • Provide the use of IF-THEN-ELSE logic within a SQL statement

CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: CASE

Using the CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE

DECODE Function Facilitates conditional inquiries by doing the work of a CASE expression or

Using the DECODE Function SELECT last_name, job_id, salary, DECODE(job_id, 'IT_PROG', 1. 10*salary, 'ST_CLERK', 1.

Using the DECODE Function Display the applicable tax rate for each employee in department

Using the DECODE Function The output is: 3 -33 Copyright © 2004, Oracle. All

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Practice • Display the data for those employees whose salary grater than number that entered by the user? ? ? Select * From employees Where salary > (: Enter the salary) • (: ) see the first word and display for user 3 -2 Copyright © 2004, Oracle. All rights reserved.

Working with Dates • • The Oracle database stores dates in an internal numeric format: century, year, month, day, hours, minutes, and seconds. The default date display format is DD-MON-RR. SELECT last_name, hire_date FROM employees WHERE hire_date < '01 -FEB-88'; 3 -4 Copyright © 2004, Oracle. All rights reserved.

Arithmetic with Dates • • • 3 -6 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. Copyright © 2004, Oracle. All rights reserved.

Using Arithmetic Operators with Dates Display the last name and the number of weeks employed for all employees in depatment 90 SELECT last_name, (SYSDATE-hire_date)/7 AS WEEKS FROM employees WHERE department_id = 90; Display the result rounded to the nearest number? SELECT last_name, round( (SYSDATE-hire_date)/7) AS WEEKS FROM employees WHERE department_id = 90; 3 -7 Copyright © 2004, Oracle. All rights reserved.

Exercise on Arithmetic with Dates Display the name and hire date of employees whose work in the company more than 10 years? Select last_name, hire_date From employees Where (sysdate-hire_date) /365 >10 3 -8 Copyright © 2004, Oracle. All rights reserved.

Date Functions 3 -9 Function MONTHS_BETWEEN Result ADD_MONTHS Add calendar months to date NEXT_DAY LAST_DAY Next day of the date specified ROUND Round date TRUNC Truncate date Number of months between two dates Last day of the month Copyright © 2004, Oracle. All rights reserved.

Using Date Functions Function Result MONTHS_BETWEEN (date 1, date 2) MONTHS_BETWEEN('01 -SEP-95', '11 -JAN-94') 19. 6774194 Try: MONTHS_BETWEEN (sysdate, ’ 01 -SEP-95’) ADD_MONTHS (date, number) ADD_MONTHS ('11 -JAN-94', 6) Try: ADD_MONTHS (SYSDATE, 3) ADD_MONTHS (sysdate, -3) ADD_MONTHS (SYSDATE, -2) 3 -10 Copyright © 2004, Oracle. All rights reserved. '11 -JUL-94'

Using Date Functions NEXT_DAY (date, day(‘string or value’)) NEXT_DAY ('01 -SEP-95', 'FRIDAY') '08 -SEP-95' Try: NEXT-DAY (sysdate, ‘Sunday') NEXT_DAY (sysdate, 1) NEXT_DAY (sysdate, -1) NEXT_DAY (sysdate, 0) LAST_DAY (date) LAST_DAY ('01 -FEB-95') Try: LAST_DAY (sysdate) 3 -11 Copyright © 2004, Oracle. All rights reserved. '28 -FEB-95'

Using Date Functions Assume SYSDATE = '25 -JUL-03': 3 -12 Function ROUND(SYSDATE, 'MONTH') Result 01 -AUG-03 ROUND(SYSDATE , 'YEAR') 01 -JAN-04 TRUNC(SYSDATE , 'MONTH') TRUNC(SYSDATE , 'YEAR') 01 -JUL-03 01 -JAN-03 Copyright © 2004, Oracle. All rights reserved.

Practice 3: Overview of Part 1 This practice covers the following topics: • Writing a query that displays the current date Select sysdate from dual • Creating queries that require the use of numeric, character, and date functions • Performing calculations of years and months of service for an employee 3 -13 Copyright © 2004, Oracle. All rights reserved.

Implicit Data Type Conversion For assignments, the Oracle server can automatically convert the following: From 3 -15 VARCHAR 2 or CHAR To NUMBER VARCHAR 2 or CHAR DATE NUMBER VARCHAR 2 DATE VARCHAR 2 Copyright © 2004, Oracle. All rights reserved.

Implicit Data Type Conversion For expression evaluation, the Oracle Server can automatically convert the following: From 3 -16 VARCHAR 2 or CHAR To NUMBER VARCHAR 2 or CHAR DATE Copyright © 2004, Oracle. All rights reserved.

Using the TO_CHAR Function with Dates TO_CHAR(date, 'format_model') The format model: • Must be enclosed by single quotation marks • 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 -18 Copyright © 2004, Oracle. All rights reserved.

Elements of the Date Format Model 3 -19 Element YYYY Result YEAR Year spelled out (in English) MM MONTH Two-digit value for 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 Full year in numbers Full name of the month Copyright © 2004, Oracle. All rights reserved.

Elements of the Date Format Model • Time elements format the time portion of the date: HH 24: MI: SS AM • 15: 45: 32 PM Add character strings by enclosing them in double quotation marks: DD "of" MONTH 12 of OCTOBER SELECT first_name, last_name, TO_CHAR(hire_date, 'DD ”of” Month “in” YYYY') AS HIREDATE FROM employees; 3 -20 Copyright © 2004, Oracle. All rights reserved.

Using the TO_CHAR Function with Numbers TO_CHAR(number, 'format_model') These are some of the format elements that you can use with the TO_CHAR function to display a number value as a character: 3 -22 Element 9 Result 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 comma as thousands indicator Represents a number Copyright © 2004, Oracle. All rights reserved.

Using the TO_NUMBER and TO_DATE Functions • Convert a character string to a number format using the TO_NUMBER function: TO_NUMBER(char[, 'format_model']) • Convert a character string to a date format using the TO_DATE function: TO_DATE(char[, 'format_model']) 3 -24 Copyright © 2004, Oracle. All rights reserved.

General Functions NVL Function Converts a null value to an actual value: • Data types that can be used are date, character, and number. • Data types must match: – – – If we Select from 3 -25 NVL(commission_pct, 0) NVL(hire_date, '01 -JAN-97') NVL(job_id, 'No Job Yet') write this, what is the result? first_name, salary, commission_pct-5 employees Copyright © 2004, Oracle. All rights reserved.

Using the NVL Function 1 SELECT last_name, salary, NVL(commission_pct, 0), (salary*12) + (salary*12*NVL(commission_pct, 0)) AN_SAL FROM employees; … 1 3 -26 Copyright © 2004, Oracle. All rights reserved. 2 2

CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: CASE expr WHEN [WHEN ELSE END 3 -28 comparison_expr 1 THEN return_expr 1 comparison_expr 2 THEN return_expr 2 comparison_exprn THEN return_exprn else_expr] Copyright © 2004, Oracle. All rights reserved.

Using the CASE Expression Facilitates conditional inquiries by doing the work of an IF-THEN-ELSE statement: SELECT last_name, job_id, salary, CASE job_id WHEN 'IT_PROG' THEN 1. 10*salary WHEN 'ST_CLERK' THEN 1. 15*salary WHEN 'SA_REP' THEN 1. 20*salary ELSE salary END "REVISED_SALARY" FROM employees; … … 3 -29 Copyright © 2004, Oracle. All rights reserved.

DECODE Function Facilitates conditional inquiries by doing the work of a CASE expression or an IF-THEN-ELSE statement: DECODE(col|expression, search 1, result 1 [, search 2, result 2, . . . , ] [, default]) 3 -30 Copyright © 2004, Oracle. All rights reserved.

Using the DECODE Function SELECT last_name, job_id, salary, DECODE(job_id, 'IT_PROG', 1. 10*salary, 'ST_CLERK', 1. 15*salary, 'SA_REP', 1. 20*salary, salary) REVISED_SALARY FROM employees; If the JOB is IT_PROG, the salary increase is 10%, If the JOB is ST_CLERK, the salary increase is 15%, If the JOB is SA_REP, the salary increas is 20%, Other , the salary is not change … … 3 -31 Copyright © 2004, Oracle. All rights reserved.

Using the DECODE Function Display the applicable tax rate for each employee in department 80? ? ? we determine the tax rate for each employee in department 80 based on the monthly salary: SELECT last_name, salary, DECODE (TRUNC(salary/2000, 0), 0, 0. 00, 1, 0. 09, 2, 0. 20, 3, 0. 30, 4, 0. 40, 5, 0. 42, 6, 0. 44, 0. 45) TAX_RATE FROM employees WHERE department_id = 80; 3 -32 Copyright © 2004, Oracle. All rights reserved. Monthly salary range Rate (0, 1000) 0% (1000, 2000) 9% (2000, 3000) 20% (3000, 4000) 30% (4000, 5000) 40% (5000, 6000) 42% (6000, 7000) 44% >=7000 45%