WHERE clause
The WHERE
clause specifies any conditions or filters to apply to your data. This allows you to select only a specific subset of the data. The WHERE
clause is used right after the FROM
clause.
Here is the basic syntax of a SELECT statement with the optional WHERE
clause:
Here, condition
is any expression that evaluates to a result of type boolean. Any row that does not satisfy this condition will be removed from the output. A row satisfies the condition if it returns true when the actual row values are substituted for any variable references. Subqueries are allowed in a condition expression.
Basic WHERE
clause example:
This query results in a table with columns for department, job title, and average salary. Each row represents the average salary for a unique combination of department and job title, and only those groups with an average salary of at least $50,000 are returned.
Notice that the WHERE
clause comes before the GROUP BY
clause in this example because the WHERE
clause is used to filter the rows in a table before any aggregations are performed. In contrast, the HAVING
clause filters data after aggregations are performed.
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