A predicate is specified in a WHERE condition in a statement which is "true", "false", or "unknown". The result is generated by applying the predicate to a specific row in a result table or to a group of rows in a table that was formed by the GROUP condition.
· Columns in a table with the same code attribute can be compared.
· Columns that have different code attributes such as ASCII and UNICODE can be compared.
· LONG columns can only be used in the NULL predicate.