mysql 數據操作 單表查詢 通過四則運算查詢

 

 

#通過四則運算查詢

SELECT name, salary*12 FROM employee;
    SELECT name, salary*12 AS Annual_salary FROM employee;
    SELECT name, salary*12 Annual_salary FROM employee;

 

查看年薪
salary*12

mysql> select name,salary*12 from employee;
+------------+-------------+
| name       | salary*12   |
+------------+-------------+
| alex       | 12000003.72 |
| yuanhao    |    42000.00 |
| liwenzhou  |    25200.00 |
| jingliyang |   108000.00 |
| jinxin     |   360000.00 |
| 成龍       |   120000.00 |
| 歪歪       |    36001.56 |
| 丫丫       |    24004.20 |
| 丁丁       |    12004.44 |
| 星星       |    36003.48 |
| 格格       |    48003.96 |
| 張野       |   120001.56 |
| 程咬金     |   240000.00 |
| 程咬銀     |   228000.00 |
| 程咬銅     |   216000.00 |
| 程咬鐵     |   204000.00 |
+------------+-------------+
16 rows in set (0.10 sec)

 

查出來的結果 這是一張虛擬表 

因為查出來結果 標注紅色的 salary*12 不太直觀 利用另外一種方式查表

 

as 給字段起別名

 

select 字段 as 別名 from 表名

mysql> select name,salary*12 as Annual_salary from employee;
+------------+---------------+
| name       | Annual_salary |
+------------+---------------+
| alex       |   12000003.72 |
| yuanhao    |      42000.00 |
| liwenzhou  |      25200.00 |
| jingliyang |     108000.00 |
| jinxin     |     360000.00 |
| 成龍       |     120000.00 |
| 歪歪       |      36001.56 |
| 丫丫       |      24004.20 |
| 丁丁       |      12004.44 |
| 星星       |      36003.48 |
| 格格       |      48003.96 |
| 張野       |     120001.56 |
| 程咬金     |     240000.00 |
| 程咬銀     |     228000.00 |
| 程咬銅     |     216000.00 |
| 程咬鐵     |     204000.00 |
+------------+---------------+
16 rows in set (0.10 sec)

 

不加as也可以 默認后面就是別名

 

mysql> select name,salary*12 Annual_salary from employee;
+------------+---------------+
| name       | Annual_salary |
+------------+---------------+
| alex       |   12000003.72 |
| yuanhao    |      42000.00 |
| liwenzhou  |      25200.00 |
| jingliyang |     108000.00 |
| jinxin     |     360000.00 |
| 成龍       |     120000.00 |
| 歪歪       |      36001.56 |
| 丫丫       |      24004.20 |
| 丁丁       |      12004.44 |
| 星星       |      36003.48 |
| 格格       |      48003.96 |
| 張野       |     120001.56 |
| 程咬金     |     240000.00 |
| 程咬銀     |     228000.00 |
| 程咬銅     |     216000.00 |
| 程咬鐵     |     204000.00 |
+------------+---------------+
16 rows in set (0.00 sec)