数据表A(dm,ztz,sj,xj),数据表B(dm1,ztz1,sj1,xj1),表B记录比A更多，求一句简单代码，检索出表A和B对应字段不相等所有记录，即使dm！=dm1或ztz！=ztz1或sj！=sj1或xj！=xj1 的所有记录。
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- SQL code
--dm,ztz,sj,xjselect * from bexceptselect * from a--如果b包含a，可以select *from b twhere not exists (select 1 from a where dm=t.dm and ztz=t.ztz and sj=t.sj and xj=t.xj)--如果b和a不是互相包含的select *from b twhere not exists (select 1 from a where dm=t.dm and ztz=t.ztz and sj=t.sj and xj=t.xj)unionselect *from a twhere not exists (select 1 from b where dm=t.dm and ztz=t.ztz and sj=t.sj and xj=t.xj)