Efficiently convert rows to columns in sql server

There are several ways that you can transform data from multiple rows into columns.

Using PIVOT

In SQL Server you can use the PIVOT function to transform the data from rows to columns:

select Firstname, Amount, PostalCode, LastName, AccountNumberfrom(  select value, columnname  from yourtable) dpivot(  max(value)  for columnname in (Firstname, Amount, PostalCode, LastName, AccountNumber)) piv;

See Demo.

Pivot with unknown number of columnnames

If you have an unknown number of columnnames that you want to transpose, then you can use dynamic SQL:

DECLARE @cols AS NVARCHAR(MAX),    @query  AS NVARCHAR(MAX)select @cols = STUFF((SELECT ',' + QUOTENAME(ColumnName)                     from yourtable                    group by ColumnName, id                    order by id            FOR XML PATH(''), TYPE            ).value('.', 'NVARCHAR(MAX)')         ,1,1,'')set @query = N'SELECT ' + @cols + N' from              (                select value, ColumnName                from yourtable            ) x            pivot             (                max(value)                for ColumnName in (' + @cols + N')            ) p 'exec sp_executesql @query;

See Demo.

Using an aggregate function

If you do not want to use the PIVOT function, then you can use an aggregate function with a CASE expression:

select  max(case when columnname = 'FirstName' then value end) Firstname,  max(case when columnname = 'Amount' then value end) Amount,  max(case when columnname = 'PostalCode' then value end) PostalCode,  max(case when columnname = 'LastName' then value end) LastName,  max(case when columnname = 'AccountNumber' then value end) AccountNumberfrom yourtable

See Demo.

Using multiple joins

This could also be completed using multiple joins, but you will need some column to associate each of the rows which you do not have in your sample data. But the basic syntax would be:

select fn.value as FirstName,  a.value as Amount,  pc.value as PostalCode,  ln.value as LastName,  an.value as AccountNumberfrom yourtable fnleft join yourtable a  on fn.somecol = a.somecol  and a.columnname = 'Amount'left join yourtable pc  on fn.somecol = pc.somecol  and pc.columnname = 'PostalCode'left join yourtable ln  on fn.somecol = ln.somecol  and ln.columnname = 'LastName'left join yourtable an  on fn.somecol = an.somecol  and an.columnname = 'AccountNumber'where fn.columnname = 'Firstname'

This is rather a method than just a single script but gives you much more flexibility.

First of all There are 3 objects:

1. User defined TABLE type [ColumnActionList] -> holds data asparameter
2. SP [proc_PivotPrepare] -> prepares our data
3. SP [proc_PivotExecute] -> execute the script

CREATE TYPE [dbo].[ColumnActionList] AS TABLE([ID] [smallint] NOT NULL,[ColumnName] nvarchar NOT NULL,[Action] nchar NOT NULL);GO

    CREATE PROCEDURE [dbo].[proc_PivotPrepare]     (    @DB_Name        nvarchar(128),    @TableName      nvarchar(128)    )    AS            SELECT @DB_Name = ISNULL(@DB_Name,db_name())    DECLARE @SQL_Code nvarchar(max)    DECLARE @MyTab TABLE (ID smallint identity(1,1), [Column_Name] nvarchar(128), [Type] nchar(1), [Set Action SQL] nvarchar(max));    SELECT @SQL_Code        =   'SELECT [<| SQL_Code |>] = '' '' '                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''-----| Declare user defined type [ID] / [ColumnName] / [PivotAction] '' '                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''DECLARE @ColumnListWithActions ColumnActionList;'''                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''-----| Set [PivotAction] (''''S'''' as default) to select dimentions and values '' '                                        + 'UNION ALL '                                        + 'SELECT ''-----|'''                                        + 'UNION ALL '                                        + 'SELECT ''-----| ''''S'''' = Stable column || ''''D'''' = Dimention column || ''''V'''' = Value column '' '                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''INSERT INTO  @ColumnListWithActions VALUES ('' + CAST( ROW_NUMBER() OVER (ORDER BY [NAME]) as nvarchar(10)) + '', '' + '''''''' + [NAME] + ''''''''+ '', ''''S'''');'''                                        + 'FROM [' + @DB_Name + '].sys.columns  '                                        + 'WHERE object_id = object_id(''[' + @DB_Name + ']..[' + @TableName + ']'') '                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''-----| Execute sp_PivotExecute with parameters: columns and dimentions and main table name'' '                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                                        + 'UNION ALL '                                        + 'SELECT ''EXEC [dbo].[sp_PivotExecute] @ColumnListWithActions, ' + '''''' + @TableName + '''''' + ';'''                                        + 'UNION ALL '                                        + 'SELECT ''----------------------------------------------------------------------------------------------------'' '                            EXECUTE SP_EXECUTESQL @SQL_Code;GOCREATE PROCEDURE [dbo].[sp_PivotExecute](@ColumnListWithActions  ColumnActionList ReadOnly,@TableName                     nvarchar(128))AS--#######################################################################################################################--###| Step 1 - Select our user-defined-table-variable into temp table--#######################################################################################################################IF OBJECT_ID('tempdb.dbo.#ColumnListWithActions', 'U') IS NOT NULL DROP TABLE #ColumnListWithActions; SELECT * INTO #ColumnListWithActions FROM @ColumnListWithActions;--#######################################################################################################################--###| Step 2 - Preparing lists of column groups as strings:--#######################################################################################################################DECLARE @ColumnName                     nvarchar(128)DECLARE @Destiny                        nchar(1)DECLARE @ListOfColumns_Stable           nvarchar(max)DECLARE @ListOfColumns_Dimension    nvarchar(max)DECLARE @ListOfColumns_Variable     nvarchar(max)--############################--###| Cursor for List of Stable Columns--############################DECLARE ColumnListStringCreator_S CURSOR FORSELECT      [ColumnName]FROM        #ColumnListWithActionsWHERE       [Action] = 'S'OPEN ColumnListStringCreator_S;FETCH NEXT FROM ColumnListStringCreator_SINTO @ColumnName  WHILE @@FETCH_STATUS = 0   BEGIN        SELECT @ListOfColumns_Stable = ISNULL(@ListOfColumns_Stable, '') + ' [' + @ColumnName + '] ,';        FETCH NEXT FROM ColumnListStringCreator_S INTO @ColumnName   ENDCLOSE ColumnListStringCreator_S;DEALLOCATE ColumnListStringCreator_S;--############################--###| Cursor for List of Dimension Columns--############################DECLARE ColumnListStringCreator_D CURSOR FORSELECT      [ColumnName]FROM        #ColumnListWithActionsWHERE       [Action] = 'D'OPEN ColumnListStringCreator_D;FETCH NEXT FROM ColumnListStringCreator_DINTO @ColumnName  WHILE @@FETCH_STATUS = 0   BEGIN        SELECT @ListOfColumns_Dimension = ISNULL(@ListOfColumns_Dimension, '') + ' [' + @ColumnName + '] ,';        FETCH NEXT FROM ColumnListStringCreator_D INTO @ColumnName   ENDCLOSE ColumnListStringCreator_D;DEALLOCATE ColumnListStringCreator_D;--############################--###| Cursor for List of Variable Columns--############################DECLARE ColumnListStringCreator_V CURSOR FORSELECT      [ColumnName]FROM        #ColumnListWithActionsWHERE       [Action] = 'V'OPEN ColumnListStringCreator_V;FETCH NEXT FROM ColumnListStringCreator_VINTO @ColumnName  WHILE @@FETCH_STATUS = 0   BEGIN        SELECT @ListOfColumns_Variable = ISNULL(@ListOfColumns_Variable, '') + ' [' + @ColumnName + '] ,';        FETCH NEXT FROM ColumnListStringCreator_V INTO @ColumnName   ENDCLOSE ColumnListStringCreator_V;DEALLOCATE ColumnListStringCreator_V;SELECT @ListOfColumns_Variable      = LEFT(@ListOfColumns_Variable, LEN(@ListOfColumns_Variable) - 1);SELECT @ListOfColumns_Dimension = LEFT(@ListOfColumns_Dimension, LEN(@ListOfColumns_Dimension) - 1);SELECT @ListOfColumns_Stable            = LEFT(@ListOfColumns_Stable, LEN(@ListOfColumns_Stable) - 1);--#######################################################################################################################--###| Step 3 - Preparing table with all possible connections between Dimension columns excluding NULLs--#######################################################################################################################DECLARE @DIM_TAB TABLE ([DIM_ID] smallint, [ColumnName] nvarchar(128))INSERT INTO @DIM_TAB SELECT [DIM_ID] = ROW_NUMBER() OVER(ORDER BY [ColumnName]), [ColumnName] FROM #ColumnListWithActions WHERE [Action] = 'D';DECLARE @DIM_ID smallint;SELECT      @DIM_ID = 1;DECLARE @SQL_Dimentions nvarchar(max);IF OBJECT_ID('tempdb.dbo.##ALL_Dimentions', 'U') IS NOT NULL DROP TABLE ##ALL_Dimentions; SELECT @SQL_Dimentions      = 'SELECT [xxx_ID_xxx] = ROW_NUMBER() OVER (ORDER BY ' + @ListOfColumns_Dimension + '), ' + @ListOfColumns_Dimension                                            + ' INTO ##ALL_Dimentions '                                            + ' FROM (SELECT DISTINCT' + @ListOfColumns_Dimension + ' FROM  ' + @TableName                                            + ' WHERE ' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = @DIM_ID) + ' IS NOT NULL ';                                            SELECT @DIM_ID = @DIM_ID + 1;            WHILE @DIM_ID <= (SELECT MAX([DIM_ID]) FROM @DIM_TAB)            BEGIN            SELECT @SQL_Dimentions = @SQL_Dimentions + 'AND ' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = @DIM_ID) +  ' IS NOT NULL ';            SELECT @DIM_ID = @DIM_ID + 1;            ENDSELECT @SQL_Dimentions   = @SQL_Dimentions + ' )x';EXECUTE SP_EXECUTESQL  @SQL_Dimentions;--#######################################################################################################################--###| Step 4 - Preparing table with all possible connections between Stable columns excluding NULLs--#######################################################################################################################DECLARE @StabPos_TAB TABLE ([StabPos_ID] smallint, [ColumnName] nvarchar(128))INSERT INTO @StabPos_TAB SELECT [StabPos_ID] = ROW_NUMBER() OVER(ORDER BY [ColumnName]), [ColumnName] FROM #ColumnListWithActions WHERE [Action] = 'S';DECLARE @StabPos_ID smallint;SELECT      @StabPos_ID = 1;DECLARE @SQL_MainStableColumnTable nvarchar(max);IF OBJECT_ID('tempdb.dbo.##ALL_StableColumns', 'U') IS NOT NULL DROP TABLE ##ALL_StableColumns; SELECT @SQL_MainStableColumnTable       = 'SELECT xxx_ID_xxx = ROW_NUMBER() OVER (ORDER BY ' + @ListOfColumns_Stable + '), ' + @ListOfColumns_Stable                                            + ' INTO ##ALL_StableColumns '                                            + ' FROM (SELECT DISTINCT' + @ListOfColumns_Stable + ' FROM  ' + @TableName                                            + ' WHERE ' + (SELECT [ColumnName] FROM @StabPos_TAB WHERE [StabPos_ID] = @StabPos_ID) + ' IS NOT NULL ';                                            SELECT @StabPos_ID = @StabPos_ID + 1;            WHILE @StabPos_ID <= (SELECT MAX([StabPos_ID]) FROM @StabPos_TAB)            BEGIN            SELECT @SQL_MainStableColumnTable = @SQL_MainStableColumnTable + 'AND ' + (SELECT [ColumnName] FROM @StabPos_TAB WHERE [StabPos_ID] = @StabPos_ID) +  ' IS NOT NULL ';            SELECT @StabPos_ID = @StabPos_ID + 1;            ENDSELECT @SQL_MainStableColumnTable    = @SQL_MainStableColumnTable + ' )x';EXECUTE SP_EXECUTESQL  @SQL_MainStableColumnTable;--#######################################################################################################################--###| Step 5 - Preparing table with all options ID--#######################################################################################################################DECLARE @FULL_SQL_1 NVARCHAR(MAX)SELECT @FULL_SQL_1 = ''DECLARE @i smallintIF OBJECT_ID('tempdb.dbo.##FinalTab', 'U') IS NOT NULL DROP TABLE ##FinalTab; SELECT @FULL_SQL_1 = 'SELECT t.*, dim.[xxx_ID_xxx] '                                    + ' INTO ##FinalTab '                                    +   'FROM ' + @TableName + ' t '                                    +   'JOIN ##ALL_Dimentions dim '                                    +   'ON t.' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = 1) + ' = dim.' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = 1);                                SELECT @i = 2                                                               WHILE @i <= (SELECT MAX([DIM_ID]) FROM @DIM_TAB)                                    BEGIN                                    SELECT @FULL_SQL_1 = @FULL_SQL_1 + ' AND t.' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = @i) + ' = dim.' + (SELECT [ColumnName] FROM @DIM_TAB WHERE [DIM_ID] = @i)                                    SELECT @i = @i +1                                ENDEXECUTE SP_EXECUTESQL @FULL_SQL_1--#######################################################################################################################--###| Step 6 - Selecting final data--#######################################################################################################################DECLARE @STAB_TAB TABLE ([STAB_ID] smallint, [ColumnName] nvarchar(128))INSERT INTO @STAB_TAB SELECT [STAB_ID] = ROW_NUMBER() OVER(ORDER BY [ColumnName]), [ColumnName]FROM #ColumnListWithActions WHERE [Action] = 'S';DECLARE @VAR_TAB TABLE ([VAR_ID] smallint, [ColumnName] nvarchar(128))INSERT INTO @VAR_TAB SELECT [VAR_ID] = ROW_NUMBER() OVER(ORDER BY [ColumnName]), [ColumnName]FROM #ColumnListWithActions WHERE [Action] = 'V';DECLARE @y smallint;DECLARE @x smallint;DECLARE @z smallint;DECLARE @FinalCode nvarchar(max)SELECT @FinalCode = ' SELECT ID1.*'                                        SELECT @y = 1                                        WHILE @y <= (SELECT MAX([xxx_ID_xxx]) FROM ##FinalTab)                                            BEGIN                                                SELECT @z = 1                                                WHILE @z <= (SELECT MAX([VAR_ID]) FROM @VAR_TAB)                                                    BEGIN                                                        SELECT @FinalCode = @FinalCode +    ', [ID' + CAST((@y) as varchar(10)) + '.' + (SELECT [ColumnName] FROM @VAR_TAB WHERE [VAR_ID] = @z) + '] =  ID' + CAST((@y + 1) as varchar(10)) + '.' + (SELECT [ColumnName] FROM @VAR_TAB WHERE [VAR_ID] = @z)                                                        SELECT @z = @z + 1                                                    END                                                    SELECT @y = @y + 1                                                END        SELECT @FinalCode = @FinalCode +                                         ' FROM ( SELECT * FROM ##ALL_StableColumns)ID1';                                        SELECT @y = 1                                        WHILE @y <= (SELECT MAX([xxx_ID_xxx]) FROM ##FinalTab)                                        BEGIN                                            SELECT @x = 1                                            SELECT @FinalCode = @FinalCode                                                                                 + ' LEFT JOIN (SELECT ' +  @ListOfColumns_Stable + ' , ' + @ListOfColumns_Variable                                                                                 + ' FROM ##FinalTab WHERE [xxx_ID_xxx] = '                                                                                 + CAST(@y as varchar(10)) + ' )ID' + CAST((@y + 1) as varchar(10))                                                                                  + ' ON 1 = 1'                                                                                 WHILE @x <= (SELECT MAX([STAB_ID]) FROM @STAB_TAB)                                                                                BEGIN                                                                                    SELECT @FinalCode = @FinalCode + ' AND ID1.' + (SELECT [ColumnName] FROM @STAB_TAB WHERE [STAB_ID] = @x) + ' = ID' + CAST((@y+1) as varchar(10)) + '.' + (SELECT [ColumnName] FROM @STAB_TAB WHERE [STAB_ID] = @x)                                                                                    SELECT @x = @x +1                                                                                END                                            SELECT @y = @y + 1                                        ENDSELECT * FROM ##ALL_Dimentions;EXECUTE SP_EXECUTESQL @FinalCode;

From executing the first query (by passing source DB and table name) you will get a pre-created execution query for the second SP, all you have to do is define is the column from your source:+ Stable+ Value (will be used to concentrate values based on that)+ Dim (column you want to use to pivot by)

Names and datatypes will be defined automatically!

I cant recommend it for any production environments but does the job for adhoc BI requests.

Please try

CREATE TABLE pvt (Present int, [Absent] int);GOINSERT INTO pvt VALUES (10,40);GO--Unpivot the table.SELECT Code, ValueFROM    (SELECT Present, Absent   FROM pvt) pUNPIVOT   (Value FOR Code IN       (Present, [Absent]))AS unpvt;GODROP TABLE pvt