T-SQL UNPIVOT’ing columns with different datatypes

Well, you can’t, really. What you have to do is to make sure that all the the columns have the same datatype and then perform the unpivot.

Here is the table I want to partially unpivot:

image

So what I do is to cast all columns to a suitable common format, in this case VARCHAR(100), before the actual pivoting:

SELECT Id, ColumnName, Value
FROM 
( SELECT 
        Id,
        CAST(SysNr AS Varchar(100)) SysNr,
        CAST(KredsNr AS Varchar(100)) KredsNr,    
        CAST(EjendomsNr AS Varchar(100)) EjendomsNr,    
        CAST(Navn AS Varchar(100)) Navn,
        CAST(EjendomStatusId AS Varchar(100)) EjendomStatusId,
        CAST(Aktiv AS Varchar(100)) Aktiv
    FROM Ejendom
) AS S
UNPIVOT
(
    Value FOR ColumnName IN (SysNr, KredsNr, EjendomsNr, Navn, EjendomStatusId, Aktiv)
) AS U

Voila – quite a bit of typing, but pretty easy peasy otherwise.

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