SQL WHERE Clause

SQL > SQL Commands > WHERE Clause

We can use the WHERE clause to filter the result set based on certain conditions. The syntax for using WHERE in the SELECT statement is as follows:

SELECT "column_name"
FROM "table_name"
WHERE "condition";

"Condition" can include a single comparison clause (called simple condition) or multiple comparison clauses combined together using AND or OR operators (compound condition).

Example 1: WHERE Clause With Simple Condition

To select all stores with sales above $1,000 in Table Store_Information,

Table Store_Information

Store_Name	Sales	Txn_Date
Los Angeles	1500	Jan-05-1999
San Diego	250	Jan-07-1999
Los Angeles	300	Jan-08-1999
Boston	700	Jan-08-1999

we key in,

SELECT Store_Name
FROM Store_Information
WHERE Sales > 1000;

Result:

Store_Name

Los Angeles

Example 2: WHERE Clause With OR Operator

To view all data with sales greater than $1,000 or with transaction date of 'Jan-08-1999', we use the following SQL,

SELECT *
FROM Store_Information
WHERE Sales > 1000 OR Txn_Date = 'Jan-08-1999';

Result:

Store_Name	Sales	Txn_Date
Los Angeles	1500	Jan-05-1999
Los Angeles	300	Jan-08-1999
Boston	700	Jan-08-1999

Using WHERE With UPDATE and DELETE

In addition to the SELECT statement, the WHERE clause can also be used with UPDATE andDELETE statements. Examples of how to use the WHERE clause with these two commands can be seen in the UPDATE and DELETE sections.