在 MySQL 中将 tinyint 默认值更改为 1?
mysqlmysqli database
您可以使用 DEFAULT 命令来实现此目的。以下是语法 −
alter table yourTableName change yourColumnName yourColumnName TINYINT(1) DEFAULT 1 NOT NULL;
首先我们创建一个表 −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserName varchar(20), UserAge int, isMarried tinyint(1) ); Query OK, 0 rows affected (0.80 sec)
让我们检查一下表的描述 −
mysql> desc DemoTable;
这将产生以下输出 −
+-----------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+----------------+ | Id | int(11) | NO | PRI | NULL | auto_increment | | UserName | varchar(20) | YES | | NULL | | | UserAge | int(11) | YES | | NULL | | | isMarried | tinyint(1) | YES | | NULL | | +-----------+-------------+------+-----+---------+----------------+ 4 rows in set (0.21 sec)
以下是将 tinyint 默认值更改为 1 的查询 −
mysql> alter table DemoTable change isMarried isMarried TINYINT(1) DEFAULT 1 NOT NULL; Query OK, 0 rows affected (1.29 sec) Records: 0 Duplicates: 0 Warnings: 0
让我们再次检查表的描述。tinyint 的默认值已更改为 1 −
mysql> desc DemoTable;
这将产生以下输出 −
+-----------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+----------------+ | Id | int(11) | NO | PRI | NULL | auto_increment | | UserName | varchar(20) | YES | | NULL | | | UserAge | int(11) | YES | | NULL | | | isMarried | tinyint(1) | NO | | 1 | | +-----------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)
