Question

我有以下查询，这是两个表的连接，你可以看到从结果我想避免来自一列的数据。从结果集下面我想避免其他行

IncidentCategory             No_Incident

Near Miss                  25
Road Events               129
Service Strike                150
Other                         Null  


SELECT BT.Name AS IncidentCategory, SUM(IR.ID) AS No_Incident  
From BBTypes BT LEFT JOIN  
     IncidentReports IR  
     ON BT.ID = IR.BbType AND
        IR.WbsElementId =  23 
GROUP BY BT.Name                
ORder By BT.Name DESC

Answer 1

在您的查询中，您使用GROUP BY，因此最好使用HAVING COUNT来提升您的查询效果。

HAVING COUNT（IR.ID）＆gt; 0是避免No_Incident列中的空行。

SELECT BT.Name AS IncidentCategory, SUM(IR.ID) AS No_Incident  
From BBTypes BT LEFT JOIN  
     IncidentReports IR  
     ON BT.ID = IR.BbType AND
        IR.WbsElementId =  23 
GROUP BY BT.Name       
HAVING COUNT(IR.ID)>0         
ORDER BY BT.Name DESC

Answer 2

如果您尝试忽略NULL行，请使用inner join代替外部联接：

SELECT BT.Name AS IncidentCategory, SUM(IR.ID) AS No_Incident  
From BBTypes BT JOIN  
     IncidentReports IR  
     ON BT.ID = IR.BbType AND
        IR.WbsElementId =  23 
GROUP BY BT.Name                
ORder By BT.Name DESC;

执行id列的总和看起来很奇怪。我猜你真的想要count()：

SELECT BT.Name AS IncidentCategory, COUNT(IR.ID) AS No_Incident  
From BBTypes BT JOIN  
     IncidentReports IR  
     ON BT.ID = IR.BbType AND
        IR.WbsElementId =  23 
GROUP BY BT.Name                
ORder By BT.Name DESC;

Answer 3

尝试添加

where BT.Name <> 'Other'

如何避免SQL Server中一列的数据

3 个答案: