在 MySQL 中用 DEFAULT 创建具有特定选项的新表?
mysqlmysqli database
为此，请在列数据类型后使用 DEFAULT 关键字。
让我们创建一个表 −
mysql> create table demo33
−> (
−> id int not null auto_increment primary key,
−> name varchar(20) not null,
−> start_date date default(current_date),
−> end_date date default NULL,
−> category enum('Good','Medium','Low') default 'Low'
−> );
Query OK, 0 rows affected (2.32 sec)
使用 insert 命令向表中插入一些记录 −
mysql> insert into demo33(name) values('John');
Query OK, 1 row affected (0.15 sec)
mysql> insert into demo33(name,end_date,category) values('David','2020−12−21','Medium');
Query OK, 1 row affected (0.09 sec)
mysql> insert into demo33(name,start_date,category) values('David','2020−04−01','Good');
Query OK, 1 row affected (0.14 sec)
mysql> insert into demo33(name,start_date,end_date,category) values('David','2020−03−10','2020−08−22','Good');
Query OK, 1 row affected (0.17 sec)
使用 select 语句显示表中的记录 −
mysql> select *from demo33;
这将产生以下输出 −
+----+-------+------------+------------+----------+ | id | name | start_date | end_date | category | +----+-------+------------+------------+----------+ | 1 | John | 2020−10−28 | NULL | Low | | 2 | David | 2020−10−28 | 2020−12−21 | Medium | | 3 | David | 2020−04−01 | NULL | Good | | 4 | David | 2020−03−10 | 2020−08−22 | Good | +----+-------+------------+------------+----------+ 4 rows in set (0.00 sec)
