Question

因此我陷入了一个我试图解决的问题。我试着这么做＆＃34;选择最常见交货类型的描述＆＃34;。我执行它但我得不到回报。我甚至尝试使用传递类型ID替换计数，但即使这样我也没有收到任何输出。我做错了什么？

Select DeliveryTypeDescription 
from DeliveryType 
group by DeliveryTypeDescription 
having count(*) >ALL(
      Select count(*) 
      from   DeliveryType 
      group by   DeliveryTypeID)

Answer 1

Select Top 1 DeliveryTypeDescription
 From  DeliveryType 
 Group By DeliveryTypeDescription 
 Order By count(*) Desc

Answer 2

在您的情况下，交付类型将是主键，因此计数永远不会超过1？

IF OBJECT_ID('tempdb..#DeliveryType') IS NOT NULL DROP TABLE #DeliveryType
CREATE TABLE #DeliveryType (DeliveryTypeID INT,DeliveryType VARCHAR(20),DeliveryTypeDescription VARCHAR(200))
INSERT INTO #DeliveryType VALUES(101,'Home','Home Delivery'),(102,'Work','Work Delivery'),(103,'Ref','Deliver to Reference'),(104,'Pick','Pickup');

SELECT DeliveryTypeDescription FROM #DeliveryType GROUP BY DeliveryTypeDescription HAVING COUNT(*) > ALL (     SELECT COUNT(*)     FROM #DeliveryType    GROUP BY DeliveryTypeID);

在那种情况下，

SELECT COUNT(*)
FROM #DeliveryType
GROUP BY DeliveryTypeID

将返回所有1,1,1,1

Answer 3

Select DeliveryTypeDescription 
from DeliveryType 
group by DeliveryTypeDescription 
having **count(*)** **>**ALL(
      **Select count(*)** 
      from   DeliveryType 
      group by   DeliveryTypeID)

您正在检索所有行，对吧？所以我认为你必须使用＆＃39;＆gt; =＆＃39;而不是＆＃39;＆＃39;。

Answer 4

好的，所以我想出了使用子查询解决这个问题的方法。我的问题首先是我没有考虑客户使用的最常见交付类型的关系。具有外键的相对表位于“客户纸张表”中。因此，我所要做的就是在“CustomerPaper”表中找到DeliverTypeID的最高计数。

SELECT  DeliveryType.DeliveryTypeDescription FROM DeliveryType 
INNER JOIN CustomerPaper
ON DeliveryType.DeliveryTypeID = CustomerPaper.DeliveryTypeID
GROUP BY DeliveryType.DeliveryTypeDescription
HAVING COUNT(CustomerPaper.DeliveryTypeID) >=ALL
(SELECT COUNT(customerpaper.DeliveryTypeID) FROM CustomerPaper GROUP BY CustomerPaper.DeliveryTypeID)

子查询我无法搞清楚

4 个答案: