WHERE Definition

WHERE clause in SQL SERVER enables you to apply one or multiple conditions before retrieving data from one or multiple tables.

WHERE Usage

We use the WHERE clause by specifying the conditions to be met for the rows to be returned.

SELECT column1, column2,... FROM table_name WHERE Condition

In order to apply multiple conditions in a WHERE query, we use the following logical operators : AND, OR

AND Operator

The AND operator signifies that all conditions must be true for a row in order to return it.

SELECT column1, column2,... FROM table_name WHERE condition1 AND condition2, ...

OR Operator

The OR operator signifies that at least one condition must be true for a row in order to return it.

SELECT column1, column2,... FROM table_name WHERE condition1 OR condition2, ...

WHERE Examples

For our examples, we will use a student table containing 10 rows of data.

To show all students older than 18 years old :

SELECT * FROM Student WHERE Age > 18

To show all male students older than 18 years old :

SELECT * FROM Student WHERE Sex = 'M' AND Age > 18

To show all students that are either born in 1985 or born in Barcelone :

SELECT * FROM Student WHERE YEAR(BirthDate) = 1985 OR City = 'Barcelone'

See also

• SELECT Clause in SQL SERVER