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Editorial Team
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Asked: 2026-06-12T01:40:21+00:00

I have a query to get records from 4 different tables. I am using

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I have a query to get records from 4 different tables. I am using union to get the final records. My problem is I don’t have same number and type of columns in all 4 tables so I am making dummy columns with null value. The problem I am facing is in sorting. I am sorting records using datetime desc, but some times when dates are same then I want the secondry sort column on alerts that can be of High, Medium or Null types. I want Null columns on bottom but I am getting on top. So I tried to use ISNULL(column_name, 'aaaa') in ORDER BY clause, but I am not getting actual result. Can any one help? 

SELECT CreatedDt as 'Date/Time' , null AS [Alert_Type] FROM TblA
union  
SELECT CreatedDt as 'Date/Time' , null AS [Alert_Type] FROM TblB
union  
SELECT CreatedDt as 'Date/Time' , null AS [Alert_Type] FROM TblC
union
SELECT CreatedDt as 'Date/Time' , Alert_Type FROM TblD
ORDER BY CreatedDt, ISNULL (Alert_Type,'aa') DESC

The error is 

ORDER BY items must appear in the select list if the statement contains a UNION, INTERSECT or EXCEPT operator.

Thank you..

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1 Answer

  1. Editorial Team

    If Alert_Type can’t be NULL in TblD, you could do this:

    SELECT CreatedDt as 'Date/Time' , 'aa' AS [Alert_Type] FROM TblA
union  
SELECT CreatedDt as 'Date/Time' , 'aa' AS [Alert_Type] FROM TblB
union  
SELECT CreatedDt as 'Date/Time' , 'aa' AS [Alert_Type] FROM TblC
union
SELECT CreatedDt as 'Date/Time' , Alert_Type FROM TblD
ORDER BY CreatedDt DESC, Alert_Type DESC

    Note the DESC after CreatedDt (because you said you wanted to sort by the datetime column in descending order).

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