在查詢時，可以為表和字段取一個別名。這個別名可以代替其指定的表和字段

為表取別名

復制代碼 代碼如下:

mysql> SELECT * FROM department d
-> WHERE d.d_id=1001;
+------+-----------+--------------+-------------+
| d_id | d_name | function| address|
+------+-----------+--------------+-------------+
| 1001 | 科技部 | 研發產品| 3號樓5層|
+------+-----------+--------------+-------------+
row in set (0.00 sec)

為字段取別名

復制代碼 代碼如下:

mysql> SELECT d_id AS department_id, d_name AS department_name
-> FROM department;
+---------------+-----------------+
| department_id | department_name |
+---------------+-----------------+
|1001 | 科技部|
|1002 | 生產部|
|1003 | 銷售部|
+---------------+-----------------+
rows in set (0.00 sec)