MySQL Database Error: You have an error in your SQL syntax....

MySQL Database Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHILE label1;

DROP FUNCTION IF EXISTS ExtractInteger;

CREATE FUNCTION ExtractInteger ( _String VARCHAR(20) )
RETURNS INT
BEGIN
SET @Count = 0;
SET @IntNumbers = '';

   label1: WHILE (@Count <= LEN(_String)) DO
    IF (SUBSTRING(_String,@Count,1) >= '0' AND SUBSTRING(_String,@Count,1) <= '9') then
    begin
    SET @IntNumbers = @IntNumbers + SUBSTRING(_String,@Count,1);
    end;
     SET @Count = (@Count + 1);
   END WHILE label1;

   RETURN @IntNumbers;

END;