EXISTS/NOT EXISTS Predicate Syntax | Teradata Vantage - 17.10 - EXISTS/NOT EXISTS Predicate Syntax - Advanced SQL Engine - Teradata Database

[NOT] EXISTS subquery

Syntax Elements

subquery

A subquery that selects the same number of expressions as are specified in the expression or list of expressions.

The subquery cannot specify a SELECT AND CONSUME statement.

The function of the EXISTS predicate is to test the result of subquery.

If execution of the subquery returns response rows then the where condition is considered satisfied.

Using the NOT qualifier for the EXISTS predicate reverses the sense of the test. Execution of the subquery does not, in fact, return any response rows. Instead, it returns a boolean result to indicate whether responses would or would not have been returned had they been requested.