MySQL Error 1064 when creating foreign key - mysql

Question

I created this using MySQL WorkBench
ALTER TABLE `android_marketplace`.`ban_utilizator`
DROP INDEX ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC);
ALTER TABLE `android_marketplace`.`ban_utilizator`
ADD CONSTRAINT `ban_utilizator_id_utilizator`
FOREIGN KEY (`id_utilizator`)
REFERENCES `android_marketplace`.`utilizatori` (`id_utilizator`)
ON DELETE NO ACTION
ON UPDATE NO ACTION;
I am getting this :
Operation failed: There was an error while applying the SQL script to the
database.
Executing:
ALTER TABLE `android_marketplace`.`ban_utilizator`
DROP INDEX ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC);
ALTER TABLE `android_marketplace`.`ban_utilizator`
ADD CONSTRAINT `ban_utilizator_id_utilizator`
FOREIGN KEY (`id_utilizator`)
REFERENCES `android_marketplace`.`utilizatori` (`id_utilizator`)
ON DELETE NO ACTION
ON UPDATE NO ACTION;
ERROR 1064: You have an error in your SQL syntax; check the manual that
corresponds to your MariaDB server version for the right syntax to use near '
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC)' at line 2
SQL Statement:
ALTER TABLE `android_marketplace`.`ban_utilizator`
DROP INDEX ,
ADD INDEX `ban_utilizator_id_utilizator_idx` (`id_utilizator` ASC)

Answer 1

The error has nothing to do with a foreign key.
You must name the index you want to drop.
Syntax error messages include the context of the problem. If the syntax error says:
check ... for the right syntax to use near '
ADD INDEX ban_utilizator_id_utilizator_idx (id_utilizator ASC)'
This means the syntax was expecting to find something else at the point where you provided ADD INDEX.
In this case, it was expecting a name for the index you tried to drop in the clause immediately preceding ADD INDEX.