Home Database Mysql Tutorial SQL Server 2000的视图中必须小心使用*符号_MySQL

SQL Server 2000的视图中必须小心使用*符号_MySQL

Jun 01, 2016 pm 02:00 PM

SQLServer2000

有些朋友看到这个标题可能会有疑问,难道在视图中使用*符号还有何要注意的地方吗?对于这个问题,我们先不必回答,先看一下例子吧。

我这里,使用的数据库是SqlServer2000自带的Northwind,这样方便大家自己私下里测试。首先,创建两个视图,视图的脚本如下:

--视图 vCustomersA

create view vCustomersA

as

select CustomerID ,CompanyName,ContactName,ContactTitle,

Address,City,Region,PostalCode,Country,Phone,Fax

from dbo.Customers

go

--视图 vCustomersB

create view vCustomersB

as

select * from vCustomersA

go

然后,使用这两个视图查询客户ID为ALFKI的资料,查询语句如下:

select * from vCustomersA where CustomerID = 'ALFKI'

select * from vCustomersB where CustomerID = 'ALFKI'

查询的结果如下:

一切正常,这个时候,需求发生了变化,我们需要改动vCustomersA,改动后的脚本如下:(为了说明问题,我们只是把CompanyName和ContactName互换一下位置)

--改动后的视图vCustomersA

alter view vCustomersA

as

select CustomerID ,ContactName,CompanyName,ContactTitle,

Address,City,Region,PostalCode,Country,Phone,Fax

from dbo.Customers

go

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