DELIMITER $$

DROP PROCEDURE IF EXISTS drop_index_if_exists $$
CREATE PROCEDURE drop_index_if_exists(in theTable varchar(128), in theIndexName varchar(128) )
BEGIN
 IF((SELECT COUNT(*) AS index_exists FROM information_schema.statistics WHERE TABLE_SCHEMA = DATABASE() and table_name =
theTable AND index_name = theIndexName) > 0) THEN
   SET @s = CONCAT('DROP INDEX `' , theIndexName , '` ON `' , theTable, '`');
   PREPARE stmt FROM @s;
   EXECUTE stmt;
 END IF;
END $$

DELIMITER ;

-- CALL drop_index_if_exists('#{index_name}','#{model_id}');