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 程式師世界 >> 數據庫知識 >> MYSQL數據庫 >> MySQL綜合教程 >> MySQL數據庫在指定位置增加字段

MySQL數據庫在指定位置增加字段

編輯:MySQL綜合教程

MySQL數據庫在指定位置增加字段


   MySQL數據庫在指定位置增加字段:

  本身屬於MySQL的基本語法,這裡給出一個例子。

  mysql> -- 測試數據庫在指定位置增加字段

  mysql> drop table if exists t;

  Query OK, 0 rows affected (0.06 sec)

  mysql> create table t(age int,address varchar(50));

  Query OK, 0 rows affected (0.06 sec)

  mysql> desc t;

  +---------+-------------+------+-----+---------+-------+

  | Field | Type | Null | Key | Default | Extra |

  +---------+-------------+------+-----+---------+-------+

  | age | int(11) | YES | | NULL | |

  | address | varchar(50) | YES | | NULL | |

  +---------+-------------+------+-----+---------+-------+

  2 rows in set (0.02 sec)

  mysql> alter table t add column name varchar(20) after age;

  Query OK, 0 rows affected (0.16 sec)

  Records: 0 Duplicates: 0 Warnings: 0

  mysql> desc t;

  +---------+-------------+------+-----+---------+-------+

  | Field | Type | Null | Key | Default | Extra |

  +---------+-------------+------+-----+---------+-------+

  | age | int(11) | YES | | NULL | |

  | name | varchar(20) | YES | | NULL | |

  | address | varchar(50) | YES | | NULL | |

  +---------+-------------+------+-----+---------+-------+

  3 rows in set (0.00 sec)

  mysql> alter table t add column id int FIRST;

  Query OK, 0 rows affected (0.13 sec)

  Records: 0 Duplicates: 0 Warnings: 0

  mysql> desc t;

  +---------+-------------+------+-----+---------+-------+

  | Field | Type | Null | Key | Default | Extra |

  +---------+-------------+------+-----+---------+-------+

  | id | int(11) | YES | | NULL | |

  | age | int(11) | YES | | NULL | |

  | name | varchar(20) | YES | | NULL | |

  | address | varchar(50) | YES | | NULL | |

  +---------+-------------+------+-----+---------+-------+

  4 rows in set (0.00 sec)

  mysql>

  相關的語法描述為

  ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name alter_specification [, alter_specification] ...alter_specification: table_option ...

  | ADD [COLUMN] col_name column_definition [FIRST | AFTER col_name ]

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