我有一张桌子:
id group_id name linked_group
1 1 Name1
2 1 Name2
3 1 Name3
4 1 Name4
5 2 Name5
6 2 Name6 3
7 2 Name7
8 3 Name8
9 3 Name9
10 4 Name10
11 4 Name11
我需要使用linked_group检索每个组中的最后一条记录:
id group_id name linked_group
4 1 Name4
9 3 Name9
11 4 Name11
怎么做? 附:我需要忽略group_id = 2,因为这个group_id需要与group_id = 3
结合答案 0 :(得分:0)
SELECT Your_tableName.id ,Your_tableName.group_id ,name,linked_group
FROM Your_tableName
JOIN (SELECT MAX(id) id, group_id
FROM Your_tableName
GROUP BY group_id) A ON A.id = Your_tableName.id
答案 1 :(得分:0)
试试这个
SELECT g.id,g.group_id,g.name,g.linked_group
FROM GroupTable g LEFT JOIN GroupTable g2
ON (g.group_id = g2.group_id AND g.id < g2.id)
WHERE g2.id IS NULL;
答案 2 :(得分:0)
如果表格不是太大,请使用以下查询。
select max_id, group_id, name from table_name , (select max(id) as max_id from table_name group by group_id) tmp where id = max_id ;
答案 3 :(得分:0)
这是使用行号模拟的另一种方法。请注意where not exists语句,以忽略具有链接组的group_ids。
select s.id,s.group_id,s.name,s.linked_group
from
(
select t.*,
if(t.group_id <> @p , @rownumber:=1,@rownumber:=@rownumber + 1) rownumber,
@p:=t.group_id
from t t, (select @rownumber:=0,@p:=0) rn
where not exists (select * from t t1 where t1.group_id = t.group_id and t1.linked_group is not null)
order by t.group_id,t.id desc
) s
where s.rownumber = 1
答案 4 :(得分:0)
试一试。希望它能起作用:))
SELECT a.*
FROM table_name a LEFT JOIN table_name b
ON (a.group_id = b.group_id AND a.id < b.id)
WHERE a.group_id <> 2 AND b.id IS NULL;