You can use DECLARE CONDITION statement to declare a user-defined condition.

Then you can define a handler for this condition using DECLARE HANDLER, and raise the condition using the SIGNAL statement.

Syntax:

DECLARE condition_name CONDITION;

Example:

Raise a condition if the number of rows is not equal to the specified number:

DECLARE cnt INT DEFAULT 0; 
DECLARE wrong_cnt_condition CONDITION;
 
DECLARE EXIT HANDLER FOR wrong_cnt_condition
  PRINT 'Wrong number of rows';  
 
SELECT COUNT(*) INTO cnt FROM TABLE (VALUES (1,2));
 
IF cnt <> 1 THEN
  SIGNAL wrong_cnt_condition;
END IF;

Compatibility: IBM DB2, Teradata and MySQL.

Version: PL/HQL 0.3.1

See also:

• Error Handling
• DECLARE HANDLER
• SQLCODE
• SQLSTATE
• GET DIAGNOSTICS
• SIGNAL
• RESIGNAL