Tạo nhiều cột GENERATED COLUMNS lưu trữ (STORED) trong MySQL với CREATE TABLE

Hoàn toàn có thể thêm nhiều cột tạo lưu trữ (stored generated columns) trong một bảng MySQL. Chúng ta minh họa qua ví dụ sau:

Ví dụ

mysql> Create table profit1(cost int, price int, profit int AS (price-cost) STORED, price_revised int AS (price-2) STORED);
Query OK, 0 rows affected (0.36 sec)
mysql> Describe profit1;
+---------------+---------+------+-----+---------+------------------+
| Field         | Type    | Null | Key | Default | Extra            |
+---------------+---------+------+-----+---------+------------------+
| cost          | int(11) | YES  |     | NULL    |                  |
| price         | int(11) | YES  |     | NULL    |                  |
| profit        | int(11) | YES  |     | NULL    | STORED GENERATED |
| price_revised | int(11) | YES  |     | NULL    | STORED GENERATED |
+---------------+---------+------+-----+---------+------------------+
4 rows in set (0.00 sec)
mysql> Insert into profit1(Cost, Price) values(100,110);
Query OK, 1 row affected (0.09 sec)
mysql> Insert into profit1(Cost, Price) values(200,220);
Query OK, 1 row affected (0.09 sec)
mysql> Select * from profit1;
+------+-------+--------+---------------+
| cost | price | profit | price_revised |
+------+-------+--------+---------------+
| 100  | 110   | 10     | 108           |
| 200  | 220   | 20     | 218           |
+------+-------+--------+---------------+
2 rows in set (0.00 sec)