How to use the MAX and Case function over three tables? - asp.net

Question

I have joined three tables using Max and Case functions.
When I used two tables it working fine but when I added the third table I got this error.
Ambiguous column name 'Month'.
SELECT Category ,
KPI ,
TDTargetValue ,
MAX(CASE WHEN Month = 'Jan' THEN Input
END) Jan ,
MAX(CASE WHEN Month = 'Feb' THEN Input
END) Feb ,
MAX(CASE WHEN Month = 'Mar' THEN Input
END) Mar ,
MAX(CASE WHEN Month = 'Apr' THEN Input
END) Apr ,
MAX(CASE WHEN Month = 'May' THEN Input
END) May ,
MAX(CASE WHEN Month = 'Jun' THEN Input
END) Jun ,
MAX(CASE WHEN Month = 'Jul' THEN Input
END) Jul ,
MAX(CASE WHEN Month = 'Aug' THEN Input
END) Aug ,
MAX(CASE WHEN Month = 'Sep' THEN Input
END) Sep ,
MAX(CASE WHEN Month = 'Oct' THEN Input
END) Oct ,
MAX(CASE WHEN Month = 'Nov' THEN Input
END) Nov ,
MAX(CASE WHEN Month = 'Dec' THEN Input
END) Dec
FROM [NEWSEMAKPI].[dbo].[NewCriteria] NC
INNER JOIN ( SELECT *
FROM [NEWSEMAKPI].[dbo].[UpdateData]
WHERE PeriodId = '1'
) UD ON UD.Cid = NC.Id
LEFT JOIN ( SELECT *
FROM [NEWSEMAKPI].[dbo].[TargetData]
) TD ON UD.Cid = TD.CId
WHERE NC.Grade = 'A'
AND IsActived = '0'
GROUP BY Category ,
KPI ,
TDTargetValue
ORDER BY 1
Any help would be appreciated.

Answer 1

Add alias also for the column Month...
Assuming NewCriteria table has the column Month
SELECT Category ,
KPI ,
TDTargetValue ,
MAX(CASE WHEN NC.Month = 'Jan' THEN Input
END) Jan ,
MAX(CASE WHEN NC.Month = 'Feb' THEN Input
END) Feb ,
MAX(CASE WHEN NC.Month = 'Mar' THEN Input
END) Mar ,
MAX(CASE WHEN NC.Month = 'Apr' THEN Input
END) Apr ,
MAX(CASE WHEN NC.Month = 'May' THEN Input
END) May ,
MAX(CASE WHEN NC.Month = 'Jun' THEN Input
END) Jun ,
MAX(CASE WHEN NC.Month = 'Jul' THEN Input
END) Jul ,
MAX(CASE WHEN NC.Month = 'Aug' THEN Input
END) Aug ,
MAX(CASE WHEN NC.Month = 'Sep' THEN Input
END) Sep ,
MAX(CASE WHEN NC.Month = 'Oct' THEN Input
END) Oct ,
MAX(CASE WHEN NC.Month = 'Nov' THEN Input
END) Nov ,
MAX(CASE WHEN NC.Month = 'Dec' THEN Input
END) Dec
FROM [NEWSEMAKPI].[dbo].[NewCriteria] NC
INNER JOIN ( SELECT *
FROM [NEWSEMAKPI].[dbo].[UpdateData]
WHERE PeriodId = '1'
) UD ON UD.Cid = NC.Id
LEFT JOIN ( SELECT *
FROM [NEWSEMAKPI].[dbo].[TargetData]
) TD ON UD.Cid = TD.CId
WHERE NC.Grade = 'A'
AND IsActived = '0'
GROUP BY Category ,
KPI ,
TDTargetValue
ORDER BY 1