Question

我试图执行以下操作：

在此国家/地区选择此制造商的所有产品

此国家/地区的每件商品均会计算指定时间段内的点击次数。

如果计数为0，则显示0。

所以我这样说：

 -- yesterday data for scrollPartial/responsive (453)
select p.Description as Product, mw.Description as Widget,  COUNT(wc.Id)as WidgetClicks   from WidgetClicks wc
join ManufacturerWidgets mw on wc.ManufacturerWidgetId = mw.Id
join Products p on p.id = wc.ProductId
where wc.ManufacturerWidgetId = 453 and wc.CreatedAt > '2013-11-24 00:00:00.000' and wc.CreatedAt < '2013-11-25 00:00:00.000'
group by  p.Description, mw.Description
 order by Product

这可以获得每种产品的点击次数 - 只要点击次数不是0。

我也试过分开这些日子：

 select DatePart(week, wc.Createdat) as WeekNumber, DatePart(day, wc.Createdat) as dateOfMonth, datename(dw, wc.Createdat) as WeekDayName,p.Description as Product, mw.Description as Widget,  COUNT(wc.Id)as WidgetClicks   from WidgetClicks wc
join ManufacturerWidgets mw on wc.ManufacturerWidgetId = mw.Id
left join  Products p on p.id = wc.ProductId
where wc.ManufacturerWidgetId =453 and wc.CreatedAt > '2013-11-24 00:00:00.000' and wc.CreatedAt < '2013-11-25 00:00:00.000'
group by DatePart(week, wc.Createdat), DatePart(day, wc.Createdat), datename(dw, wc.Createdat), p.Description, mw.Description
 order by WeekNumber, dateOfMonth, WeekDayName, Product

并按产品选择并进行左连接：

 select p.Description as Product, COUNT(wc.ProductId) as clicks from Products p
join productcountries pc on p.Id = pc.ProductId
 LEFT JOIN widgetclicks wc ON p.Id = wc.ProductId
where pc.CountryId = 231 and p.ManufacturerId = 129  and p.Discontinued = 0 and  wc.ManufacturerWidgetId =453 and wc.CreatedAt > '2013-11-20 00:00:00.000' and wc.CreatedAt < '2013-11-25 00:00:00.000' 
group by  p.Description

如果我取消以下内容：

wc.ManufacturerWidgetId =453 and wc.CreatedAt > '2013-11-20 00:00:00.000' and wc.CreatedAt < '2013-11-25 00:00:00.000'

我可以看到0次点击次数，所以我认为必须是因为我在where子句中有widgetclick表。？

所以我希望我的表看起来像

Product Name    Widget Name    Click Count
Product1        Widget1         73
Product2        Widget1          0
Product3        Widget1          4
Product4        Widget1          2

非常感谢任何帮助！

Answer 1

你快到了。考虑一下sql在执行GROUP BY语句之前所做的中间结果集。如果WidgetClicks表中没有Product 2 / Widget 1的记录，则不能使用Inner Join，因为那时结果集没有任何Widget 1记录。

LEFT JOIN是一个很好的一步，但是你用这个位淘汰了Product 2 / Widget 1行：

wc.CreatedAt > '2013-11-20 00:00:00.000' and wc.CreatedAt < '2013-11-25 00:00:00.000'

您的集合中的产品2 / Widget 1的行在wc.CreatedAt字段中具有NULL。 LEFT JOIN正常工作并使用Product 2 / Widget 1创建了一个中间集，但随后WHERE子句将它们过滤掉了。

解决方案是将这些条件移动到连接中。条件筛选出哪些widgetclicks记录被考虑，但由于条件不再在WHERE中，因此它不适用于包含products位的结果集。

select p.Description as Product, COUNT(wc.ProductId) as clicks 
from Products p
  join productcountries pc on p.Id = pc.ProductId
  LEFT JOIN widgetclicks wc 
    ON p.Id = wc.ProductId
      and  wc.ManufacturerWidgetId =453 
      and wc.CreatedAt > '2013-11-20 00:00:00.000' 
      and wc.CreatedAt < '2013-11-25 00:00:00.000'
where pc.CountryId = 231 and p.ManufacturerId = 129  and p.Discontinued = 0   
group by  p.Description

Answer 2

尝试这样的事情抱歉的代码没有经过测试，也许没有工作它仅用于实例

select p.*, wc.cnt
  from Product p
  left join (select wc.ProductId, count(*) as cnt
               from WidgetClicks wc
              where wc.ManufacturerWidgetId = 453
                and wc.CreatedAt > '2013-11-24 00:00:00.000'
                and wc.CreatedAt < '2013-11-25 00:00:00.000') wc
    on (p.productid = wc.productid)

如果没有，SQL包括count 0

2 个答案: