Search conditions

To specify a search condition for a WHERE clause, a HAVING clause, a CHECK clause, a JOIN clause, or an IF expression.

{ expression compare expression
| expression compare { ANY | SOME| ALL } ( subquery )
| expression IS [ NOT ] NULL
| expression [ NOT ] BETWEEN expression AND expression
| expression [ NOT ] LIKE expression [ESCAPE expression]
| expression [ NOT ] IN ( { expression  | subquery  |
... value-expr1 , value-expr2 [, value-expr3 ] … } )
| column-name [ NOT ] CONTAINS ( … word1  [, word2,] [, word3 ] … )
| EXISTS ( subquery )
| NOT condition
| condition AND condition
| condition OR condition
| ( condition )
| ( condition , estimate )
| condition IS [ NOT ] { TRUE | FALSE | UNKNOWN }

compare:
{  = | > | < | >= | <= | <> | != | !<  | !> }

Anywhere

Must be connected to the database

For example, the following query retrieves the names and birth years of the oldest employees:

SELECT name, year_of_birth 
FROM employees 
WHERE year_of_birth <= ALL (SELECT year_of_birth FROM employees);

The subqueries that provide comparison values for quantified comparison predicates might retrieve multiple rows but can have only one column.

None

Conditions are used to choose a subset of the rows from a table, or in a control statement such as an IF statement to determine control of flow.