Question

这是我有一个更大的查询。我想返回所有利润中心的列表，事件计数在日期范围内。我希望列出利润中心，即使日期范围内没有报告任何事件。这一直很好。

然而，现在已经引入了一些利润中心为NULL的记录。我希望那些在列表中显示为'N / A'的事件计数为NULL。

SELECT DISTINCT cast(plants.profit_ctr as varchar(50)) + ' - ' + cast(plants.profit_ctr_name as varchar(50)) AS Profit_Center, COALESCE(h.Incident_Count, 0) AS Incident_Count 
FROM JMART.[safety].vwHELPForms AS plants
LEFT OUTER JOIN
(SELECT profit_ctr, COUNT(*) AS Incident_Count
FROM JMART.[safety].vwHELPForms 
WHERE cast(rec_date as date) >= cast(@startdate as date) 
AND cast(rec_date as date) <= cast(@enddate as date) AND ratings > 0 
GROUP BY  profit_ctr) AS h
ON h.profit_ctr = plants.profit_ctr

我该如何做到这一点？

修改的

如果我跑

SELECT profit_ctr, COUNT(*) AS Incident_Count
FROM JMART.[safety].vwHELPForms 
WHERE cast(rec_date as date) >= cast(@startdate as date) 
AND cast(rec_date as date) <= cast(@enddate as date) AND ratings > 0 
GROUP BY  profit_ctr

我得到了

NULL    295
101100  7483
101150  116
101200  445
101400  3784

我试过

SELECT DISTINCT cast(plants.profit_ctr as varchar(50)) + ' - ' + cast(plants.profit_ctr_name as varchar(50)) AS Profit_Center, 
COALESCE((SELECT COUNT(*) AS Incident_Count FROM JMART.[safety].vwHELPForms AS h
WHERE profit_ctr = plants.profit_ctr AND cast(rec_date as date) >= cast(@startdate as date) 
AND cast(rec_date as date) <= cast(@enddate as date) AND ratings > 0 
GROUP BY  profit_ctr), 0) AS Incident_Count
FROM JMART.[safety].vwHELPForms AS plants 
order by Profit_Center

给了我（与我目前得到的相同）

NULL    0
101100      7483
101150  116
101200      445
101400      3784

我想要

N/A     295
101100      7483
101150  116
101200      445
101400      3784

Answer 1

NULL值将进入连接中的第二个表，而不是第一个表。所以，它们被left outer join迷失了。相反，您想使用full outer join：

SELECT DISTINCT
       coalesce(cast(plants.profit_ctr as varchar(50)) + ' - ' + cast(plants.profit_ctr_name as varchar(50)), 'N/A') AS Profit_Center,
       COALESCE(h.Incident_Count, 0) AS Incident_Count 
FROM JMART.[safety].vwHELPForms plants full OUTER JOIN
     (SELECT profit_ctr, COUNT(*) as Incident_Count
      FROM JMART.[safety].vwHELPForms 
      WHERE cast(rec_date as date) >= cast(@startdate as date) AND
            cast(rec_date as date) <= cast(@enddate as date) AND ratings > 0 
      GROUP BY  profit_ctr
     ) h
     ON h.profit_ctr = plants.profit_ctr

假设profit_ctr表中没有重复plants，您可以省略distinct。它增加了不必要的处理，可能不需要。

Answer 2

由于您使用的是LEFT JOIN，因此空利润中心会在结果中显示为NULL。由于您使用DISTINCT，因此它们将折叠为一行。对于Incident_Count列，您可以使用coalesce(cast(h.Incident_Count as varchar(50)), 'N/A')

PS。我假设您正在使用MS SQL Server 2012。

返回包含null的一列的所有不同值，然后根据条件进行计数

2 个答案: