SQL Alias(别名)
通过使用 SQL,别名(Alias)可用于列名称和表名称。
列名别名
语法:
SELECT 列名称 AS 列的别名 FROM 表名称
表名称别名
语法:
SELECT 列名称 FROM 表名称 AS 表的别名
实例: 使用一个列名别名
表 Persons:
LastName |
FirstName |
Address |
City |
Adams |
John |
Oxford Street |
London |
Bush |
George |
Fifth Avenue |
New York |
Carter |
Thomas |
Changan Street |
Beijing |
SQL:
SELECT LastName AS Family
, FirstName AS Name
FROM Persons
结果:
Family |
Name |
Adams |
John |
Bush |
George |
Carter |
Thomas |
实例: 使用一个表名称别名
表 Persons:
LastName |
FirstName |
Address |
City |
Adams |
John |
Oxford Street |
London |
Bush |
George |
Fifth Avenue |
New York |
Carter |
Thomas |
Changan Street |
Beijing |
SQL:
SELECT LastName, FirstName FROM Persons AS Employees
结果:
表 Employees:
LastName |
FirstName |
Adams |
John |
Bush |
George |
Carter |
Thomas |