Description
A basic predicate compares two values using a relational operator (see Relational Operators for information). If a basic predicate specifies a query expression, then the query expression must return a single value. Basic predicates often specify an inner join. See Inner Joins for more detail.
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.
Syntax
basic_predicate ::
expr relop { expr | (query_expression) }