Condition

Use a condition to test whether data meets certain qualifications. Use this segment wherever you see a reference to a condition in a syntax diagram.

Syntax


Condition

   .-Logical_Operator-----------------------------.   
   V                                      (1)     |   
|----+-----+--+-| Comparison Conditions |-------+-+-------------|
     '-NOT-'  |                             (2) |     
              +-| Condition with Subquery |-----+     
              |                           (3)   |     
              '-| User-Defined Function |-------'

Notes:

Element	Description	Restrictions	Syntax
Logical _Operator	Combines two conditions	Valid options are OR ( = logical union) or AND ( = logical intersection)	Conditions with AND or OR

Usage

A condition is a search criterion, optionally connected by the logical operators AND or OR. Conditions can be classified into the following categories:

Comparison conditions (also called filters or Boolean expressions)
Conditions with a subquery
User-defined functions (Informix® only)

A condition can contain an aggregate function only if it is used in the HAVING clause of a SELECT statement or in the HAVING clause of a subquery.

No aggregate function can appear in a condition in the WHERE clause of a DELETE, SELECT, or UPDATE statement unless both of the following are TRUE:

Aggregate is on a correlated column originating from a parent query.
The WHERE clause appears in a subquery within a HAVING clause.

In Informix, user-defined functions are not valid as conditions in the following contexts:

In the HAVING clause of a SELECT statement
In the definition of a check constraint

SPL routines are not valid as conditions in the following contexts:

In the definition of a check constraint
In the ON clause of a SELECT statement
In the WHERE clause of a DELETE, SELECT, or UPDATE statement

External routines are not valid as conditions in the following contexts:

In the definition of a check constraint
In the ON clause of a SELECT statement
In the WHERE clause of a DELETE, SELECT, or UPDATE statement
In the WHEN clause of CREATE TRIGGER
In the IF, CASE, or WHILE statements of SPL