How Can I Easily Transpose Columns and Rows in SQL?
Jan 23, 2025 am 10:57 AMEasily implement SQL column and row transposition
In SQL, it is often necessary to exchange rows and columns. While PIVOT seems like a suitable tool, there are situations where it appears to be overly complex. Fortunately, there are some easier alternatives to achieve this conversion.
Use UNION ALL, aggregate functions and CASE statements
If PIVOT seems daunting, you can use UNION ALL combined with an aggregate function and a CASE statement to replicate its functionality:
select name, sum(case when color = 'Red' then value else 0 end) Red, sum(case when color = 'Green' then value else 0 end) Green, sum(case when color = 'Blue' then value else 0 end) Blue from ( select color, Paul value, 'Paul' name from yourTable union all select color, John value, 'John' name from yourTable union all select color, Tim value, 'Tim' name from yourTable union all select color, Eric value, 'Eric' name from yourTable ) src group by name
UNPIVOT and PIVOT using static values
If you know the specific column and color you want to convert, you can hardcode it for static execution:
select name, [Red], [Green], [Blue] from ( select color, name, value from yourtable unpivot ( value for name in (Paul, John, Tim, Eric) ) unpiv ) src pivot ( sum(value) for color in ([Red], [Green], [Blue]) ) piv
Use dynamic UNPIVOT and PIVOT to handle unknown values
For cases where the number of columns and colors is unknown, dynamic SQL can be used to generate the necessary lists:
DECLARE @colsUnpivot AS NVARCHAR(MAX), @query AS NVARCHAR(MAX), @colsPivot as NVARCHAR(MAX) select @colsUnpivot = stuff((select ','+quotename(C.name) from sys.columns as C where C.object_id = object_id('yourtable') and C.name <> 'color' for xml path('')), 1, 1, '') select @colsPivot = STUFF((SELECT ',' + quotename(color) from yourtable t FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)') ,1,1,'') set @query = 'select name, '+@colsPivot+' from ( select color, name, value from yourtable unpivot ( value for name in ('+@colsUnpivot+') ) unpiv ) src pivot ( sum(value) for color in ('+@colsPivot+') ) piv' exec(@query)
No matter which method you choose, the results are the same:
| NAME | RED | GREEN | BLUE |
| Eric | 3 | 5 | 1 |
| John | 5 | 4 | 2 |
| Paul | 1 | 8 | 2 |
| Tim | 1 | 3 | 9 |
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