Tutorial for SQL Keyword WHERE - u3schools

Back Next

SQL WHERE

The sql WHERE statement is used to select the data from the table with some conditions. This WHERE keyword comes follwed by the table name in SELECT statement. The General syntax of the sql WHERE statement is given below:

SELECT *
FROM table_name
WHERE column_name operator value

In WHERE statement used operators for checking the conditions. Some of the major operators list is given below.

Operator	Operator description
=	Check the column_name and value is equal
<>	Check the column_name and value is not equal
>	Check the column_name is greater than value
<	Check the column_name is less than value
>=	Check the column_name is greater than or equal to value
<=	Check the column_name is less than or equal to value
LIKE	allows you to do search based on pattern
IN	allows you to do search based on value
BETWEEN	allows you to do search based on range

Let us assume that we have the following table it shows the temperature information about the cities in india. Table name is temperature_information:

City	AverageTemperature	Date
Chennai	26 C	11/21/2008
Bombay	27 C	11/10/2008
Calcutta	30 C	11/25/2008
Bangalore	18 C	10/09/2008
Delhi	28 C	12/29/2008
Kochin	17 C	12/19/2008

Example 1:

Executed Query:

SELECT * FROM temperature_information WHERE City = 'Chennai'

Result:

City	AverageTemperature	Date
Chennai	26 C	11/21/2008

Description:
it shows the chennai city temperature status with all columns.

Example 2:

Executed Query:

SELECT
AverageTemperature
FROM temperature_information WHERE City = 'Bangalore'

Result:

AverageTemperature

18 C

Description:
it shows only the average temperature of the city bangalore.

Example 3:

Executed Query:

SELECT * FROM temperature_information WHERE AverageTemperature > 20

Result:

City	AverageTemperature	Date
Chennai	26 C	11/21/2008
Bombay	27 C	11/10/2008
Calcutta	30 C	11/25/2008
Delhi	28 C	12/29/2008

Description:
it shows the temperature details which average temperature is above than 20.

Example 4:

Executed Query:

SELECT * FROM temperature_information WHERE Date = '10/09/2008'

Result:

City	AverageTemperature	Date
Bangalore	18 C	10/09/2008

Description:
it shows the temperature details which is Date equals 10/09/2008.

Back Next