Thursday, 15 December 2011

SQL Where

The WHERE clause is used to extract only those records that fulfill a specified criterion.


SQL WHERE Syntax



SELECT column_name(s)
FROM table_name
WHERE column_name operator value

The "CustMast" Table

custcode
custname
city
qty
rate
1
Siva
Srivilliputtur
50
70
2
Bala
Sivakasi
30
56
3
Kanna
Madurai
100
200
4
Vijay
Chennai
30
30
5
Kodee
Srivilliputtur
60
30
5
Kodee
Srivilliputtur
60
30

                                                         
                                                           For TEXT  values Examples: 

Ex: 1

Select CustName,City from CustMast where Custname='Siva'

OutPut :

custname
city
Siva
Srivilliputtur


Ex: 2

Wrong Below Coding

Select CustName,City from CustMast where Custname=Siva

Error : Invalid column name 'siva'.

Note: ( SQL uses single quotes around text values (most database systems will also accept double quotes).Although, numeric values should not be enclosed in quotes.)



                                                   For NUMERIC  values Examples:


This is correct:


SELECT * FROM Persons WHERE Year=1965


This is wrong:


SELECT * FROM Persons WHERE Year='1965'




Operators Allowed in the WHERE Clause. With the WHERE clause, the following operators can be used:





Operator
Description
=
Equal
<>
Not equal
>
Greater then
<
Less than
>=
Greater than or equal
<=
Less than or equal
BETWEEN
Between an inclusive range
LIKE
Search for a pattern
IN
If you know the exact value you want to return for at least one of the columns




Note: In some versions of SQL the <> operator may be written as !=

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