Question

我试图计算次数＆＃34; on＆＃34;发生在多个列中。第一个查询返回我想要的内容，但是当我尝试第二个查询时，它只返回没有结果的列标题。如果有人能告诉我错误的原因，我只是回到sql。

此查询返回所需的结果：

DECLARE @MainHospital varchar(50)='HOSPITAL 1';

SELECT 
    mainhospital, COUNT([chkInpatient]) as 'Inpatient Count'
FROM 
    SurveyPicList
WHERE 
    MainHospital = @MainHospital 
    AND chkInpatient = 'on'
GROUP BY 
    MainHospital

这只返回5个列标题，但没有结果：

DECLARE @MainHospital varchar(50)='HOSPITAL 1';

SELECT 
    mainhospital, 
    COUNT([chkInpatient]) AS 'Inpatient Count', 
    COUNT([chkPartB]) AS 'PartB Count', 
    COUNT([chkOutpatient]) AS 'Outpatient Count', 
    COUNT([chkER]) AS 'ER Count'
FROM 
    SurveyPicList
WHERE 
    MainHospital = @MainHospital 
    AND chkInpatient = 'on' 
    AND chkPartB = 'on' 
    AND chkOutpatient = 'on' 
    AND chkER = 'on'
GROUP BY 
    MainHospital

Answer 1

您似乎想要单独计算每列。使用条件聚合，而不是where子句：

DECLARE @MainHospital varchar(50)='HOSPITAL 1';

SELECT mainhospital,
       SUM(CASE WHEN [chkInpatient] = 'on' THEN 1 ELSE 0 END) as "Inpatient Count",
       SUM(CASE WHEN [chkPartB] = 'on' THEN 1 ELSE 0 END) as 'PartB Count',
       SUM(CASE WHEN [chkOutpatient] = 'on' THEN 1 ELSE 0 END) as "Outpatient Count",
       SUM(CASE WHEN [chkER] = 'on' THEN 1 ELSE 0 END) as "ER Count"
FROM SurveyPicList
WHERE MainHospital = @MainHospital
GROUP BY MainHospital;

您的查询无效的原因是没有行将所有四列设置为on，这是您在where子句中所要求的。

请注意，我还更改了列别名以使用双引号。仅对字符串和日期常量使用单引号。

Answer 2

您的第二个查询是查找chkInpatient，chkPartB，chkOutpatient和chkER都在＆＃39; on＆＃39; 每个记录。这就是为什么你没有收到任何记录？

SQL Server：简单的COUNT查询

2 个答案: