确定fk的行是否存在于20个表中的任何一个表中

我不确定我是否理解这个问题。以下情况会改善您的情况吗?

if exists(select * from Table1 where ForeignKeyColumn = searchValue)
  or exists(select * from Table2 where ForeignKeyColumn = searchValue)
  or exists(select * from Table3 where ForeignKeyColumn = searchValue)
  or ...

假设这20个表保持一致,那么对每个表使用一个左外部联接怎么样。这可能是一种低效的方法,但应该有效

select Id from 
    (Select PK.id, isnull(tbl1.fk,0) as fk1, isnull(tbl2.fk,0) as fk2 ... etc
    from pk left join tbl1 on pk.id = tbl1.fk left join
        tbl2 on pk.id = tbl2.fk ... etc) as VirtualTable
Where fk1>0 or fk2>0 ... etc

那么,您正在尝试确定是否可以删除某一行?

begin tran;
delete tablename
where id = 3;
rollback tran;

比如说:

if exists (
 select * from Table1 where MyKey = @key
 union
 select * from Table2 where MyKey = @key
 union
 select * from Table3 where MyKey = @key
 ...
)

我面前没有打开一个SQL server实例,所以我肯定它的某个地方有语法错误,但您知道的是=)