Chapter Six Data Manipulation Language (DML) Functions Objectives Single Row functions Character functions Number functions Date functions.

Chapter SixData Manipulation Language (DML)Functions

Objectives Single Row functions Character functions Number functions Date functions

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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 returned type Can be nested

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Single Row Functions Character Number Date Conversion General

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Character Manipulation: LOWER(Col | Exp)

LOWER(‘Database course’)

UPPER (Col | Exp)UPPER (‘Database course’)

INITCAP (Col | Exp)INITCAP (‘Database course’)

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Practice:

Display last name and first name of customers. Last name in upper case. First character of each first name in upper case, the rest in lower case.

Example:

SMITH Lori

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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,’.’)

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Character Manipulation LENGTH(Col | Exp)

LENGTH(‘this is it’)

CHR(integer)CHR(97)

INSTR(‘Computer’,’m’)

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List(Characters): Example:

SELECT LOWER(name), UPPER(major), LENGTH(name)

FROM student;

SELECT CONCAT(Name , Address) , GPAFROM Student;

  SELECT Name || ‘--->‘ || Address , GPA

FROM Student;

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List(Characters): SELECT RPAD (Name, 40, ‘.’), GPA

FROM Student;JOHN............... 3.1MARY ............. 3.2

SELECT RPAD (Name, 20), GPAFROM Student;

MARY 3.2 MOHAMMAD 3.3

SELECT LPAD (Name, 20), GPAFROM Student;

MARY 3.2 MOHAMMAD 3.3

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Practice:

Display the last name and address of each customer together. In the next column display customer phone number.

SMITH 11 MAIN ST FROSTBURG MD……..301 689 1111

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List(Characters): RTRIM(Col)

RTRIM (Name)RTRIM (Name, ‘.’)LTRIM (Name, ‘ABC’)

 LTRIM ( RTRIM( Name, ‘.’ ), ‘a’)From Student;

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Practice:

Customer phone number is stored as: -301-689-1111:

Part 1- We would like to delete the first dash and the last colon from the phone numbers:

-301-689-1111:Part 2- Remove all dashes and colon

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List(Characters): SELECT Name

FROM StudentWHERE LENGTH(Address)<20;

SELECT Name, SUBSTR (SSN, 5 ,2)

FROM Student;

SELECT Name, SUBSTR (SSN,5)FROM Student;

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List(Characters): SELECT RPAD

(INITCAP(LOWER(Name)),70,’.’), SUBSTR (SSN,5)

FROM Student;

SELECT NameFROM StudentWHERE SUBSTR (SSN,5,2)=’80’;

SELECT Name, SUBSTR (SSN,-4)FROM Student;

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Practice:

Display the 10 characters from OrderPart description starting at location 6.

Example:Door Replacement Handle

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List(Characters): SELECT Name, INSTR (Name,’r’)

FROMStudent;  ------------------------------------------------

MARY 3JOHN 0ROBIN 1

SELECT Name, INSTR (Name,’r’,1,2)FROMStudent;

SELECT Name, INSTR(Address,’Frostburg’)FROMStudent;

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Practice:

We would like to switch the position of last name with the first name. Assume the attribute name consists of both first and last names with a blank character in between.

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LIST(Numbers) ROUND (value, precision)

ROUND(234.1161,2)

TRUNC(value, precision)TRUNC(234.1161,2)

POWER(value,exponent)POWER(3,2) 

MOD(value1, value2)MOD(900,400)

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LIST(Numbers) SELECT ROUND(Salary,1)

FROM Faculty;

SELECT TRUNC(234.111,2), FROM DUAL;

TRUNC(234.567);TRUNC(234.5678,-2);

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DATE: Date is stored in an internal numeric

format: century, year, month, day, hours, minutes, second

Default date is DD-MON-YY

SYSDATE

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DATE: Example:

List the ages of students  SELECT name, SYSDATE -

B_DateFROM student;

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Practice:

Display today’s date.

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

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DATE: MONTHS_BETWEEN(day1,day2)

SELECT name, MONTHS_BETWEEN(SYSDATE , B_Date)

age_in_month

FROM Student;

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DATE: ADD_MONTHS (date,n) SELECT name,

ADD_MONTHS(B_Date,5) age

FROM Student;

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DATE: ROUND(date [,fmt])  SELECT name, ROUND

(B_Date,’MONTH’)FROM Student;

SELECT name, ROUND(B_Date,’YEAR’)FROM Student;

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Conversion Function:

Implicit conversion (Automatic):

CHAR or VARCHAR2 to NUMBER CHAR or VARCHAR2 to DATE NUMBER to VARCHAR2 DATE to VARCHAR2

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Conversion Function:

Explicit datatype conversion:

TO_CHAR (NUMBER [,‘fmt’] ) TO_CHAR (DATE [,‘fmt’] ) TO_DATE (CHAR [,‘fmt’] ) TO_NUMBER (CHAR [,‘fmt’] )

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Conversion Function:

SELECT TO_CHAR(b_date,’MM/YY’)FROM student;

Format: YYYY YEAR MM MONTH DY DAY

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Conversion Function:

SELECTSUBSTR(TO_CHAR(111223333),1,3)

||‘-’ || SUBSTR

(TO_CHAR(111223333),4,2) || ‘-’ ||SUBSTR(TO_CHAR(111223333),6)

FROM Student;

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Conversion Function:

SELECT SUBSTR(ssn,1,3) || ‘-’ || SUBSTR(ssn,4,2) || ‘-’ ||SUBSTR(ssn,6)

FROM Student;