Question

我是SQL的新手，如果你能帮助我，我将不胜感激。我有一个表有一个具有许多ID的字段，该字段是数字格式。相同的ID可以重复不同的次数，例如5次，6次。我希望仅在相同ID在此字段中重复少于x次时才显示所有字段的记录。哪个sql语句会完成这个？

提前致谢。

Answer 1

试试这个：

SELECT T1.* FROM TableName T1
INNER JOIN 
(SELECT ID,COUNT(ID) as Count
FROM TableName
GROUP BY ID
HAVING COUNT(ID) < 5) T2 ON T1.ID=T2.ID

修改

使用别名尝试查询：

SELECT APropertyID,BPropertyID,Ayy,Byy from (SELECT a.PropertyID as APropertyID, b.PropertyID as BPropertyID, a.yy as Ayy,b.yy as Byy FROM tableA a full outer join tableB b on a.PropertyID=b.PropertyID ) a1 inner join (SELECT PropertyID,COUNT(PropertyID) as Count FROM tableA GROUP BY PropertyID HAVING COUNT(PropertyID) < 5) c on a1.APropertyID=c.PropertyID

Answer 2

SQL Server允许在聚合中使用OVER Clause（这是一个非常有用但非标准的＃34; SQL功能），在这种情况下很方便。

在应用关联的窗口函数之前确定行集的分区和排序。也就是说，OVER子句定义查询结果集中的窗口或用户指定的行集。然后，窗口函数计算窗口中每行的值。您可以将OVER子句与函数一起使用来计算聚合值，例如移动平均值，累积聚合，运行总计或每组结果的前N个。

示例：

SELECT cts.*
FROM (
    -- Build intermediate result where each record also has
    -- a count of how many times that value appears.
    SELECT
        t.*,
        COUNT (1) OVER (PARTITION BY value) as valueCount
    FROM t
) as cts
-- Filter intermediate result based on collected count.
WHERE cts.valueCount < 5

（我已使用value代替上面的ID - 同样的方法也适用。）

Answer 3

SELECT * 
FROM MyTable
WHERE ID IN
  (SELECT ID
  FROM MyTable
  GROUP BY ID
  HAVING COUNT(1) < 5)

仅从表中选择字段值重复小于x次的记录

3 个答案: