作业帮select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么?
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select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么?
select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么?
select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么?
我是这样理解的：因为TOP 子句用于规定要返回的记录的数目,作用于整张表,例如SELECT TOP 50 PERCENT ,只是显示整张表的一半数目,后台数据库处理还是一张表,前台查询的返回结果是不同于临时表.所以虽然你查询出前五条,但是后台数据库处理max还是作用于整张account表 .所以得到的值是整张account表中account_id的最大值.select max(account_id) from account where account_id in (select top 5 account_id from account)
sql=select * from x where Min>2 and max
select max(account_id ) from(select top 5 account_id from account)子查询没起作用为什么?
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