Release 10.1A: OpenEdge Data Management:
SQL Reference

Basic Predicate

A basic predicate compares two values using a relational operator. If a basic predicate specifies a query expression, then the query expression must return a single value. Basic predicates often specify an inner join.

If the value of any expression is null or the query_expression does not return any value, then the result of the predicate is set to false.

This is the syntax for a basic_predicate:

Syntax

expression relop { expression | ( query_expression ) }