TSQL，删除基于行指数排

Question

我的表是这样的.....

---

**AttName**  **Title**  **Count_Index** 

Red    Boys    1 
Red    Girls    2 
Green    Boys    1 
Blue    Boys    1 

我只想要回...因为我

Red Boys  1 
Red Girls  2 

那有两个条目的红色，我想跳过/删除所有的行，如果他们的计数是只有1.换句话说，我只对行的兴趣，如果他们的计数超过“1”。

Answer 1

尝试

SELECT * 
    FROM table1 
WHERE AttName IN (SELECT AttName FROM table1 GROUP BY AttName HAVING COUNT(*) > 1) 

SQLFiddle

输出

| ATTNAME | TITLE | COUNT_INDEX | 
--------------------------------- 
|  Red | Boys |   1 | 
|  Red | Girls |   2 | 

Answer 2

好的，这是测试。在寻找重复项目时，我喜欢使用窗口功能。特别是因为避免在where子句中进行子选择，并且从同一个表中进行两次。相反，所有需要的列已被拉入子查询中。尽管开窗功能有时可能很昂贵。

Select *, ROW_NUMBER() over (Partition by AttrName Order By AttrName) --probably better to order by whatever the primary key is for consistent results, esepcially if you plan to use this in a delete statement 
From (
    SELECT AttName, title, COUNT(AttrName) over (partition by AttrName) as cnt 
    FROM yourtable 
) as counted 
Where counted.cnt > 1