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SQL SErvEr 查询的并交差集合运算的实际开发的实用性

将两条查询语句作为子查询的一部分连表. select t1.count1+t2.count2 as 'countSum',t1.branch (select count as count1, branch from table1 group by branch)t1 (select count as count2, branch from table2 group by branch)t2 on t1.branch...

--SQL集合操作 UNION --并集 INTERSECT --交集 EXCEPT --差集

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