如何使用 CREATE TABLE 语句在 MySQL 表中拥有多个虚拟生成列?

如何使用 CREATE TABLE 语句在 MySQL 表中拥有多个虚拟生成列?

很可能在 MySQL 表中添加多个虚拟生成列。可以用以下示例来说明:

示例

mysql> Create table profit(cost int, price int, profit int AS (price-cost), price_revised int AS (price-2));
Query OK, 0 rows affected (0.73 sec)
mysql> Describe profit;
+---------------+---------+------+-----+---------+-------------------+
| Field         | Type    | Null | Key | Default | Extra             |
+---------------+---------+------+-----+---------+-------------------+
| cost          | int(11) | YES  |     | NULL    |                   |
| price         | int(11) | YES  |     | NULL    |                   |
| profit        | int(11) | YES  |     | NULL    | VIRTUAL GENERATED |
| price_revised | int(11) | YES  |     | NULL    | VIRTUAL GENERATED |
+---------------+---------+------+-----+---------+-------------------+
4 rows in set (0.00 sec)
mysql> Insert into profit(Cost, Price) values(100,110);
Query OK, 1 row affected (0.04 sec)
mysql> Insert into profit(Cost, Price) values(200,220);
Query OK, 1 row affected (0.04 sec)
mysql> Select * from profit;
+------+-------+--------+---------------+
| cost | price | profit | price_revised |
+------+-------+--------+---------------+
| 100  | 110   | 10     | 108           |
| 200  | 220   | 20     | 218           |
+------+-------+--------+---------------+
2 rows in set (0.00 sec)
原文来自:www.php.cn
© 版权声明
THE END
喜欢就支持一下吧
点赞15 分享
评论 抢沙发
头像
欢迎您留下宝贵的见解!
提交
头像

昵称

取消
昵称表情代码图片

    暂无评论内容