HP 3000 Manuals

ALLBASE/SQL Reference Manual

EXISTS Predicate 

An EXISTS predicate tests for the existence of a row satisfying the
search condition of a subquery.  The predicate evaluates to TRUE if at
least one row satisfies the search condition of the subquery.

Scope 

SQL Data Manipulation Statements

SQL Syntax 

EXISTS SubQuery 

Parameters 

SubQuery                A subquery is a nested query.  The syntax of
                        subqueries is presented in the description of the
                        SELECT statement in the "SQL Statements" chapter.

Description 

Unlike other places in which subqueries occur, the EXISTS predicate
allows the subquery to specify more than one column in its select list.

Example 

Get supplier names for suppliers who provide at least one part.

     SELECT S.SNAME
       FROM S
      WHERE EXISTS  ( SELECT * FROM SP
                     WHERE SP.SNO = S.SNO );

MPE/iX 5.5 Documentation