SQL 一个表的多个别名
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Multiple Alias names for a table
提问by Deviprasad Das
Can we have multiple alias names for a single table?
一个表可以有多个别名吗?
回答by ConcernedOfTunbridgeWells
Yes. You need to do this for a self join,for example f you have a table storing a hierarchy:
是的。您需要为自联接执行此操作,例如,如果您有一个存储层次结构的表:
create table Foo (
FooID int
,ParentFooID int
,[columns]
)
You can do a join to get the children of parents that satisfy a particular condition with a query like:
您可以使用以下查询进行连接以获取满足特定条件的父母的孩子:
Select b.*
from Foo a
join Foo b
on a.FooID = b.ParentFooID
and [some condition filtering a]
回答by Chris Diver
No, not on the same table, but you can select the same table twice and give each a different alias.
不,不是在同一张桌子上,但是您可以两次选择同一张桌子并给每个桌子赋予不同的别名。
SELECT alias1.*, alias2.*
FROM mytable alias1, mytable alias2
This will then allow you to use the same table for a different purpose within a single query.
这将允许您在单个查询中将同一个表用于不同的目的。