Multi level unique is very important feature in mysql. This feature is present all databases. Using composite unique key we can achieve multilevel uniqueness. In article for create multi level unique id in mysql. Using this composite unique key we can achieve multilevel uniqueness.
create multi level unique id in mysql
Here I am going to give you how to create the composite unique key in mysql.
mysql> alter table `user` add unique `DATE_uuid` (`date`, `uuid`)
how to check indexes on table
mysql> show index from user;
+—————-+————+————+————–+————-+———–+————-+———-+——–+——+————+———+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+—————-+————+————+————–+————-+———–+————-+———-+——–+——+————+———+
| user | 0 | PRIMARY | 1 | user_id | A | 0 | NULL | NULL | | BTREE | |
| user | 0 | DATE_uuid | 1 | date | A | NULL | NULL | NULL | | BTREE | |
| user | 0 | DATE_uuid | 2 | uuid | A | 0 | NULL | NULL | | BTREE | |
+—————-+————+————+————–+————-+———–+————-+———-+——–+——+————+———+
3 rows in set (0.01 sec)
mysql>
