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

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Condition

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

Notes:
  1. See Comparison Conditions (Boolean Expressions)
  2. See Condition with Subquery
  3. See User-Defined Functions

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