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Synopsis

IF condition
  THEN statements
  [ ELSEIF condition THEN statements ]
  [ ... ]
  [ ELSE statements ]
END IF

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Description

The IF THEN statement is an optional construct to allow conditional processing in SQL routines. Each condition following an IF or ELSEIF must evaluate to a boolean. The result of processing the expression must result in a boolean true value to process the statements in the THEN block. A result of false results in skipping the THEN block and moving to evaluate the next ELSEIF and ELSE blocks in order. The ELSEIF and ELSE segments are optional.

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Examples

FUNCTION simple_if(a bigint)
  RETURNS varchar
  BEGIN
    IF a = 0 THEN
      RETURN 'zero';
    ELSEIF a = 1 THEN
      RETURN 'one';
    ELSE
      RETURN 'more than one or negative';
    END IF;
  END
Further examples of varying complexity that cover usage of the IF statement in combination with other statements are available in the SQL routines examples documentation.

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See also