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HomeBackend DevelopmentPHP Tutorial来帮我看看这个mysql语句该怎么写!

test
name      add           num

a               wefsv         3

b               asdf          4
b               wers         9
b               w1rs         10

as             asdf          11
as             wers         12
as            w3rs         13

例如上面这个表,我需要用select * from test......

来选出如下结果(每个name中num最大的那个,只要一行,其它不管!)
a               wefsv         3
b               w1rs         10
as            w3rs         13

再多此一问,如果要选择2行怎么办?

b               wers         9
b               w1rs         10

as             wers         12
as            w3rs         13

a               wefsv         3


回复讨论(解决方案)

slect name,add,num from test group by add order by add desc

slect name,add,num from test group by add order by add desc


大神!不行啊!每个选出num不是最大的

每个name最大的一行
select *
from test a
where not exists (select 1 from test where name=a.name and num>a.num);

第一问

select * from (select * from test order by num desc) t group by name
name add   num a    wefsv 3 as   w3rs  13 b    w1rs  10 

第一问

select * from (select * from test order by num desc) t group by name
name add   num a    wefsv 3 as   w3rs  13 b    w1rs  10 

1 行

select * from test a where 0 =  (select count(*) from test where name = a.name and num > a.num)

2 行

select * from test a where 2 >  (select count(*) from test where name = a.name and num > a.num)

1 行

select * from test a where 0 =  (select count(*) from test where name = a.name and num > a.num)

2 行

select * from test a where 2 >  (select count(*) from test where name = a.name and num > a.num)



太牛了!昨天我弄了半小时都弄不出来!,谢谢!你这方法我感觉最好!

问题二

select * from test t where 2>(select count(*) from test where num>t.num and name=t.name);
name add   num a    wefsv 3 b    wers  9 b    w1rs  10 as   wers  12 as   w3rs  13 


所以问题一的又一写法是
select * from test t
 where  1>(select count(*) from test1 where num>t.num and name=t.name)

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