DROP COLUMN

    1. CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, col1 INT NOT NULL, col2 INT NOT NULL);
    1. Query OK, 0 rows affected (0.12 sec)
    1. INSERT INTO t1 (col1,col2) VALUES (1,1),(2,2),(3,3),(4,4),(5,5);
    1. Query OK, 5 rows affected (0.02 sec)
    2. Records: 5  Duplicates: 0  Warnings: 0
    1. +----+------+------+
    2. | id | col1 | col2 |
    3. +----+------+------+
    5. |  3 |    3 |    3 |
    6. |  4 |    4 |    4 |
    7. |  5 |    5 |    5 |
    8. +----+------+------+
    9. 5 rows in set (0.01 sec)
    1. ALTER TABLE t1 DROP COLUMN col1, DROP COLUMN col2;
    1. ERROR 1105 (HY000): can't run multi schema change
    1. SELECT * FROM t1;
    1. ALTER TABLE t1 DROP COLUMN col1;
    1. Query OK, 0 rows affected (0.27 sec)
    1. | id | col2 |
    2. +----+------+
    3. |  1 |    1 |
    4. |  2 |    2 |
    5. |  3 |    3 |
    6. |  4 |    4 |
    7. |  5 |    5 |
    8. +----+------+
    9. 5 rows in set (0.00 sec)
    • 目前不支持在一条语句中同时删除多个列。
    • 目前不支持删除主键列或组合索引相关列。