SQL Server unpivot multiple columns

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[愿得一人]
[愿得一人] 2021-01-17 08:44

I\'m trying to pivot a table around it\'s many columns to get to 3 columns (pivot, column name, value)

so for example:

name  |  age  |  gender
------         


        
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  • 2021-01-17 09:21
    SELECT name, column, value
    FROM (SELECT name, age, gender
    FROM table) src
    UNPIVOT (value FOR column IN (age, gender)) pvt
    
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  • 2021-01-17 09:29

    The conversion of columns into rows is called an UNPIVOT. You didn't specify what version of SQL Server you are using but there are several different ways to get the result.

    You can use SELECT with UNION ALL:

    SELECT name, 'age' as column, cast(age as varchar(10)) as value
    FROM yourtable
    UNION ALL
    SELECT name, 'gender' as column, gender as value
    FROM yourtable;
    

    If you are using SQL Server 2005+, then you can use the UNPIVOT function:

    SELECT name, column, age
    FROM
    (
      SELECT 
        name, 
        age = cast(age as varchar(10)), 
        gender
      FROM yourtable
    ) d
    UNPIVOT
    (
      value
      for column in (age, gender)
    ) unpiv;
    

    Finally, instead of the UNPIVOT function you could also use CROSS APPLY with either VALUES (2008+) or UNION ALL:

    SELECT name, column, age
    FROM yourtable
    CROSS APPLY
    (
      VALUES
        ('age', cast(age as varchar(10)),
        ('gender', gender)
    ) c (column, value);
    

    Any of these versions will give you the result that you want. You'll note that I had to cast the age column to a varchar. This is because the datatype/length (in unpivot) of the columns must be the same since you will be transforming them into a single column in the final result.

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