MySQL Workbench generates combined primary key with unnecessary unique constraints - mysql

Question

I have a problem during SQL generation of my database diagram from MySQL Workbench (UNIQUE constraints are added in every field from combined primary key).
I have following diagram: https://dl.dropboxusercontent.com/u/3843729/baza.png
Moreover, it has following properties set: https://dl.dropboxusercontent.com/u/3843729/indexes.png
SQL generated:
CREATE TABLE IF NOT EXISTS `test`.`User_has_Menu` (
`User_id` BIGINT UNIQUE NOT NULL,
`Menu_id` BIGINT UNIQUE NOT NULL,
PRIMARY KEY (`User_id`, `Menu_id`),
INDEX `fk_User_has_Menu_Menu1_idx` (`Menu_id` ASC),
INDEX `fk_User_has_Menu_User1_idx` (`User_id` ASC),
CONSTRAINT `fk_User_has_Menu_User1`
FOREIGN KEY (`User_id`)
REFERENCES `test`.`User` (`id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `fk_User_has_Menu_Menu1`
FOREIGN KEY (`Menu_id`)
REFERENCES `test`.`Menu` (`id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;
As you can see, 'User_id' and 'Menu_id' have UNIQUE keyword, so as a result I cannot insert single user_id (or menu_id) in two rows, for example:
insert into user_has_menu (user_id, menu_id) values (1,1);
insert into user_has_menu (user_id, menu_id) values (1,3);
Second insert statement is not executed as user_id must be unique.
Note: If I create new diagram in MySQL Workbench, everything is working fine and the SQL generated is without problematic UNIQUE constraints.
How can I remove those constraints without creating new diagram?

Answer 1

first find the unique constraint names:
select *
from
information_schema.key_column_usage
where
and table_schema = 'my_database'
and table_name = 'my_table'
then drop them
alter table my_table drop index my_contraint
And because unique constraints are handled as indexes on MySQL you can try make sure you don't have these indexes on the MySQL graphical interface.