Filters & Conditions

Filtering

Sometimes we may only want to return values that fall within a specific range or based on a particular set of conditions.

-- select all values where country = "DO"
SELECT *
FROM locations
WHERE country='DO';

This query returns all columns from the locations table where data in the country field is equal to DO. The data returned by this query includes all the records for locations in the Dominican Republic.

Other comparison operators in SQL include:

Operator	Description
=	Equal to
>	Greater than
<	Less than
>=	Greater than or equal to
<=	less than or equal to
<>	Not equal to
BETWEEN	Between a specified range
LIKE	Searches for a pattern based on similarity
IN	Specifies multiple possible values for a column

WHERE

For more on operators that can be used in a WHERE clause (from W3Schools SQL Where Clause page).

We can also use operators to specify a range for the WHERE clause.

-- select values where dob is greater than 1996
SELECT *
FROM players
WHERE dob>1996;

This query returns all columns from players where data in the dob field is greater than 1996. SQL query syntax requires single quotes around text values. Numeric fields do not need single quotes.