SQL Functions - Oracle SQL Fundamentals

SQL Fundamentals Oracle 11g
M U H A M M A D WA H E E D
O R AC L E DATA BA S E D E V E LO P E R
E M A I L : m .wa h e e d 3 6 6 8 @ g m a i l . co m
Lecture#6
SQL Functions

SQL Functions(cont’d)
Functions are powerful feature of SQL and can be used to do the
following:
•Perform calculations on data
•Modify individual data items
•Manipulate output for group of rows
•Format dates and numbers for display
•Convert column data type
3

SQL Functions(cont’d)
There are following two types of SQL functions:
•Single Row Functions
Operate on single rows only and return single result per row.
•Multiple Row Functions
Can be used to manipulate group of rows to generate single result
against group of rows and also known as “Group Functions”.
*For now, We will consider only single-row functions.
4

Single-Row Functions
There are following types of single-row functions:
5

Single-Row(cont’d)
There are following types of character function:
6

Character Functions
There are following case-manipulation functions:
•LOWER(<column_name>|<expression>)
converts alpha characters to lowercase
•UPPER(<column_name>|<expression>)
converts alpha characters to uppercase
•INITCAP(<column_name>|<expression>)
capitalize the first letter of each word
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Character Functions(cont’d)
•CONCAT(<column_name1>|<expression1>,
(<column_name2>|<expression2>))
equivalent to concatination operator
•SUBSTR(<column_name>|<expression>,M[,N])
returns characters starting from m and ending at n. As n is optional
if it is skipped then by default characters are returned from m to end
of characters.
•LENGTH(<column_name>|<expression>)
returns total no. of characters
8

9

10

Use of Character Functions
11
•Example:
SELECT std_id, CONCAT(std_first_name,std_last_name) AS
std_name, LENGTH(std_address), INSTR( std_address, ‘#’)
FROM student
WHERE SUBSTR(std_name,2,3) = ‘ai’;

Number Functions
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•Number functions input as well as output only numeric values.

Number Functions(cont’d)
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•Number functions input as well as output only numeric values.

Number Functions(cont’d)
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•It can have negative value of ‘n’.
•Example:
SELECT ROUND(45.926,-1) FROM DUAL;
Result: 50
SELECT TRUNC(45.926,-2) FROM DUAL;
Result: 0

Date Functions
15
•For current date we use:
SELECT SYSDATE FROM DUAL;
Result( standard/default format): 26-APR-18

Arithmetic - Date Functions(cont’d)
18

Use Date Functions(cont’d)
19
•Example:
SELECT std_id, (SYSDATE - admission_date)/ 7 AS weeks
FROM student;

Use Date Functions(cont’d)
20

Implicit type casting
21
•For assignments, Oracle server can automatically convert following:

Implicit type casting(cont’d)
22
•For expression, Oracle server can automatically convert following:

Explicit type casting(cont’d)
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Type casting - Date Functions(cont’d)
25
•Example:
i- SELECT std_id, TO_CHAR(admission_date,’MM/YY’)
FROM student;
ii- SELECT std_id, TO_CHAR(admission_date,’Day Month DD,YYYY’)
AS “Admission Date”
FROM student;
iii- SELECT std_id, TO_CHAR(admission_date,’fmDay Month DD,YYYY’)
AS “Admission Date”
FROM student;

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•Example:
i- SELECT std_id, TO_DATE(’27-APR-2018,’MM/YY’)
FROM student;
ii- SELECT std_id, TO_DATE(‘MAY 27,2018’,’fxMonth DD,YYYY’) AS
“Admission Date”
FROM student;

27
•Example:
SELECT std_id, TO_CHAR(admission_date,’ fmDD MONTH,YYYY
fmHH12:MI:SS AM’)
FROM student;
•Result(TO_CHAR): 26 APRIL,2018 2:00:00 PM

NVL Function
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•Converts a null value to an actual value
•Syntax:
NVL(<column/experession>,<value>)
•Used with NUMBER,VARCHAR2 and DATE datatypes
•Data types must match for actual value
- NVL(std_age,0)
- NVL(std_address,’Pakistan’)
- NVL(std_dob,’01-JAN-00’)

CASE Function
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•It provides IF-THEN-ELSE nesting facility in SQL
•Syntax:

CASE Function(cont’d)
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•Example:
SELECT tch_id,tch_name,tch_salary,
CASE tch_designation WHEN ‘VISITING’ salary*1.1
WHEN ‘ASSISTANT LECTURER’ salary*1.2
WHEN ‘LECTURER’ salary*1.5
ELSE salary END AS “Revised Salary”
FROM teacher;
•*Note: same functionality can be performed using DECODE in
Oracle. Do it by yourself.

Records Manipulation Function
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•There are few such functions: COUNT,MAX,MIN
•Example:
i- SELECT COUNT(*) FROM student;
ii- SELECT MAX(tch_salary) FROM teacher;
iii- SELECT MIN(std_dob) FROM student;

Nested Single-row Functions
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•Single functions can be nested to any level.

Nested Single-row Functions
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•Single functions can be nested to any level.
SELECT NVL(TO_CHAR(std_dob,’MON DD,YYYY’),’NO VALUE’)
FROM student;

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SQL Functions - Oracle SQL Fundamentals

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