カラム名の変更
changeの場合
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ALTER TABLE [テーブル名] CHANGE [現在のカラム名] [新しいカラム名] [型]; |
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mysql> describe test; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | age | int | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.01 sec) mysql> alter table test change age years_old int; Query OK, 0 rows affected (0.00 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> describe test; +-----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | years_old | int | YES | | NULL | | +-----------+-------------+------+-----+---------+-------+ 2 rows in set (0.01 sec) |
カラムの型の変更
changeの場合
ALTER TABLE … CHANGEで変更するが、新しいカラムでも現在のカラム名を指定する必要がある。
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ALTER TABLE [テーブル名] CHANGE [現在のカラム名] [新しいカラム名｝[変更後の型]; |
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mysql> describe test; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | age | int | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) mysql> alter table test change age age tinyint; Query OK, 0 rows affected (0.02 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> describe test; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | age | tinyint | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) |
modifyの場合
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ALTER TABLE test MODIFY [カラム名] [変更後の型]; |
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mysql> describe test; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | age | int | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) mysql> alter table test modify age tinyint; Query OK, 0 rows affected (0.03 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> describe test; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | age | tinyint | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) |