SQL Server 中的嵌套选择语句

2022-01-07 00:00:00 nested sql subquery sql-server querying

为什么下面的方法不起作用?

Why doesn't the following work?

SELECT name FROM (SELECT name FROM agentinformation)

我想我对 SQL 的理解是错误的，因为我原以为这会返回与

I guess my understanding of SQL is wrong, because I would have thought this would return the same thing as

SELECT name FROM agentinformation

内部的 select 语句不是创建一个结果集，然后外部的 SELECT 语句会查询吗?

Doesn't the inner select statement create a result set which the outer SELECT statement then queries?

推荐答案

您需要为子查询添加别名.

You need to alias the subquery.

SELECT name FROM (SELECT name FROM agentinformation) a

或者更明确

SELECT a.name FROM (SELECT name FROM agentinformation) a

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