Question

我有一个SQL查询，为我提供了一个包含数据库中双记录的列表。

select periodid, itemid from periodscore  
group by periodid, itemid
having count(*) > 1

这可以按预期工作，但现在我想检索这些记录的其他字段（例如上次更新的日期等）。所以我试过了：

select * from periodscore where periodscoreid in
(select periodscoreid from periodscore  
group by periodid, itemid
having count(*) > 1)

当然这不起作用并给我错误：

列'periodscore.PeriodScoreID'是因为它在选择列表中无效不包含在任何一个聚合函数或GROUP BY 子句。

如何检索此查询中的额外字段？

Answer 1

select ps.* 
from periodscore ps
inner join (
    select periodid, itemid 
    from periodscore   
    group by periodid, itemid 
    having count(*) > 1
) psm on ps.periodid = psm.periodid and ps.itemid = psm.itemid

Answer 2

  select p1.* from periodscore p1 JOIN 
  (select periodid, itemid from periodscore  
   group by periodid, itemid
   having count(*) > 1) p2
   ON (p1.periodId = p2.periodId
       AND p1.itemid = p2.itemid)

如果periodid或item具有空值，则

  select p1.* from periodscore p1 JOIN 
  (select periodid, itemid from periodscore  
   group by periodid, itemid
   having count(*) > 1) p2
   ON (IFNULL(p1.periodId,0) = IFNULL(p2.periodId,0))
       AND IFNULL(p1.itemid,0) = IFNULL(p2.itemid,0))

从SQL子查询中获取更多详细信息

2 个答案: