怎么把这两条SQL语句写成一条语句_ASP.NET

如何把这两条SQL语句写成一条语句。
两个表中通过iDCID关联
首先通过一次查询得到A表的iDCID值，然后用这个之去查B表。

步骤是：1〉select iDCID from KHGL_Customer where iCustomerId=@iCustomerId

2〉select iDCID,cDCName from basic_DistrictClass where basic_DistrictClass.iDCID=KHGL_Customer.iDCID

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select iDCID,cDCName from basic_DistrictClass where basic_DistrictClass.iDCID in ( select iDCID from KHGL_Customer where iCustomerId=@iCustomerId )
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SQL code

select iDCID,cDCName from basic_DistrictClass where basic_DistrictClass.iDCID in ( select iDCID from KHGL_Customer where  iCustomerId=@iCustomerId )
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C# codeselect iDCID,cDCName from basic_DistrictClass where basic_DistrictClass.iDCID in ( select iDCID from KHGL_Customer where  iCustomerId=@iCustomerId )
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select k.iDCID,b.cDCName from KHGL_Customer as k join basic_DistrictClass b on k.iDCID=b.iDCID where  iCustomerId=@iCustomerId