MySQL 중복 제거

개요

MySQL 중복 제거

mysql> SELECT * FROM test1;
+----+-------+-----------+
| id | id2   | str       |
+----+-------+-----------+
|  1 | 11111 | hello     |
|  2 | 11111 | world     |
|  3 | 22222 | hello     |
|  4 | 22222 | world     |
|  5 | 11111 | my friend |
+----+-------+-----------+
5 rows in set (0.00 sec)

mysql> ALTER IGNORE TABLE test1 ADD UNIQUE INDEX(id2);
Query OK, 5 rows affected (0.05 sec)
Records: 5  Duplicates: 3  Warnings: 0

mysql> SELECT * FROM test1;
+----+-------+-------+
| id | id2   | str   |
+----+-------+-------+
|  1 | 11111 | hello |
|  3 | 22222 | hello |
+----+-------+-------+
2 rows in set (0.00 sec)