主从表查询,该如何处理_Sql Server

主从表查询
主表字段

SQL code

id inttitle varchar

从表字段

SQL code

id intparentid int  --主表的IDfilename varchar

简单的1对n的关系,要求查出主表中的25条,filename不为空的记录;从表的记录没有约定,只要一条filename不为空即满足条件.

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SQL code

select top 25 a.* from ta a join tb b on a.id=b.parentid where b.filename is not null or filename<>''
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SQL codeselect top 25 a.* from tb a,tb b where a.id=b.id and b.filename is not null
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SQL codeSELECT  TOP 25 a.* FROM  ta a,tb b WHERE a.id=b.parentid AND( b.filename is not null AND b.filename<>'')
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SQL codeselect top 25 p.id,p.title,s.filename from temp_main as p inner join temp_detail as son p.id=s.parentid where filename is not null or filename<>''