Chúng ta sẽ minh họa qua ví dụ tạo cột tạo lưu trữ (stored generated column) trong bảng tên employee_data_stored. Như đã biết, cột tạo lưu trữ được tạo bằng từ khóa STORED.
Ví dụ
mysql> Create table employee_data_stored(ID INT AUTO_INCREMENT PRIMARY KEY, First_name VARCHAR(50) NOT NULL, Last_name VARCHAR(50) NOT NULL, FULL_NAME VARCHAR(90) GENERATED ALWAYS AS(CONCAT(First_name,' ',Last_name)) STORED);
Query OK, 0 rows affected (0.52 sec)
mysql> DESCRIBE employee_data_stored;
+------------+-------------+------+-----+---------+------------------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+------------------+
| ID | int(11) | NO | PRI | NULL | auto_increment |
| First_name | varchar(50) | NO | | NULL | |
| Last_name | varchar(50) | NO | | NULL | |
| FULL_NAME | varchar(90) | YES | | NULL | STORED GENERATED |
+------------+-------------+------+-----+---------+------------------+
4 rows in set (0.00 sec)
mysql> INSERT INTO employee_data_stored(first_name, Last_name) values('Gaurav','Kumar');
Query OK, 1 row affected (0.04 sec)
mysql> INSERT INTO employee_data_stored(first_name, Last_name) values('Raman','Singh');
Query OK, 1 row affected (0.09 sec)
mysql> Select * from employee_data_stored;
+----+------------+-----------+--------------+
| ID | First_name | Last_name | FULL_NAME |
+----+------------+-----------+--------------+
| 1 | Gaurav | Kumar | Gaurav Kumar |
| 2 | Raman | Singh | Raman Singh |
+----+------------+-----------+--------------+
2 rows in set (0.00 sec)