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
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