如何在 SQL 中查找重复记录？

Question

我正在尝试开发一个查询来插入唯一记录，但由于尝试插入重复记录而收到 SQL Server 主键错误。我能够使用此查询插入一些值，但不能插入此记录（score_14）。

所以现在我正在尝试使用以下查询查找重复记录。挑战在于我的 PK 基于 3 列：StudentID、MeasureDate 和 MeasureID——全部来自下面未提及的不同表。

但这只会显示计数——而不是我只想返回计数 > 1 的记录。我该怎么做？

select count(a.score_14) as score_count, A.studentid, A.measuredate, B.measurename+' ' +B.LabelName 
from [J5C_Measures_Sys] A
join [J5C_ListBoxMeasures_Sys] B on A.MeasureID = B.MeasureID 
join sysobjects so on so.name = 'J5C_Measures_Sys' 
join syscolumns sc on so.id = sc.id 
join [J5C_MeasureNamesV2_Sys] v on v.Score_field_id = sc.name
where so.type = 'u' and sc.name = 'score_14' and a.score_14 is not null 
AND A.STUDENTID IS NOT NULL AND A.MEASUREDATE IS NOT NULL AND B.MEASURENAME IS NOT NULL
--and count(a.score_14)>1
group by a.studentid, a.measuredate, B.measurename, B.LabelName, A.score_14
having count(a.score_14) > 1

Answer 1

Beth 是正确的 - 这是我对您的查询的重写：

SELECT a.studentid, a.measuredate, a.measureid
  from [J5C_Measures_Sys] A
GROUP BY a.studentid, a.measuredate, a.measureid
  HAVING COUNT(*) > 1

以前：

SELECT a.studentid, a.measuredate, a.measureid
  from [J5C_Measures_Sys] A
  join [J5C_ListBoxMeasures_Sys] B on A.MeasureID = B.MeasureID 
  join sysobjects so on so.name = 'J5C_Measures_Sys'
                    AND so.type = 'u'
  join syscolumns sc on so.id = sc.id 
                    and sc.name = 'score_14' 
  join [J5C_MeasureNamesV2_Sys] v on v.Score_field_id = sc.name
 where a.score_14 is not null  
   AND B.MEASURENAME IS NOT NULL
GROUP BY a.studentid, a.measuredate, a.measureid
  HAVING COUNT(*) > 1

Answer 2

如果你想计算它，你需要把 A.score_14 从你的 group by 子句中去掉