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union orDEr By

union使用时必须时前后连接的操作语句一模一样,order by 进行排序时也要选取相同的参数。

(select top 9 * from table1 order by id) union (select top 19 * from table2 order by id) union (select top 99 * from table3 order by id) 你如果想union之后再order by的话得使用子查询

select t.* from(select xx,yy,zz from t1union allselect xx,yy,zz from t2union all……) torder by 字段

您好,我来为您解答: select a,b,c,d from (select t1.a,t1.b,t1.c from t1 where t1.e = ' ' union all select t2.a,t2.b,t2.c from t2 where t2.e = ' ') order by a order by的优先级比union all 要低,因此如果有union ,会先执行union,再...

order by只能用于外部查询中,不能应用于子查询中。 上面的sql,union all合并了2个sql查询结果集,order by当成union all合并结果集的排序,但是结果集中无表a和字段bqdm。 select * from (select a.bqdm,sum(a.zyrs) 今日在院人数 from YZCX_Y...

子查询一般是不建议orderby的 可以union之后在orderby 如果有要求需要子查询orderby的话 可以对着需要orderby的sql select top 一下 例如: select top 1000 * from A orderby id union select top 1000 * from A orderby name

union和order by连用需要放在子查询中,否则会报错 例如: 错误写法: select * from dept1 order by deptno union select * from dept2 order by deptno; ORA-00933 "SQL command not properly ended" 正确写法: select * from (select * from...

select * from ( select u.*, r.statusname, p.*, c.* from UserLogin U, RepairStatus R, Product P, Customer C where U.status = R.statusid and U.ProductName = P.ProductName and U.BoatName = C.BoatName and U.RepairDate

union 是去前后两个结果集的并集且取出重复项, 只需要最后order by排序结果就行了,在前面结果1的排序 UNION 结果2的排序 UNION 结果三的排序。 可以直接吧所有表结果并在一起,然后排序. 你可以试试,应该结果一样

在前面在加一列,然后把union all 的结果放到子查询中,用来排序 比如: select * from (select 0+a ord,t.* from where a is not null union all select 1+b ord,t.* from where a is not null ) ta order by ord

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