SQL 服务器将行转换为列

Question

I have a table like this with 145.695 rows.

SERVER	TAPE
ACS08	M00030L3
ACS08	M00253L3
ACS09	M00580L3
ACS09	M00602L3
ACS10	M00580L4
ACS10	M00602L5
ACS10	M00602L7

Now I want to reach a target table structure like this:

ACS08	ACS09	ACS10
M00030L3	M00580L3	M00580L4
M00253L3	M00602L3	M00602L5
		M00602L7

I need help because I dont know how can I do.

Answer 1

You can use dynamic pivot to get the desired results.

First we need to generate the dynamic columns based on the [SERVER] column values and then pivot the values as per the requirement:

DECLARE @cols NVARCHAR(MAX), @query NVARCHAR(MAX);

SET @cols = STUFF((SELECT DISTINCT ','+ QUOTENAME([SERVER])
                     FROM T FOR XML PATH(''), TYPE
                    ).value('.', 'nvarchar(max)'), 1, 1, '');   --XML way of getting the column values

SET @query = 'SELECT '+@cols+' from 
                (
                    SELECT [SERVER], [TAPE], ROW_NUMBER() OVER (PARTITION BY [SERVER] ORDER BY (SELECT NULL)) as RN --We need to add a unique number to select all rows while doing aggregation for the PIVOT
                    FROM T
                )x 
                PIVOT (max([TAPE]) for [SERVER] in ('+@cols+')
            ) PVT';

EXECUTE (@query);

Please find the db<>fiddle here .

Answer 2

Try this:

DECLARE @Columns nvarchar(max), @Sql nvarchar(max);

SELECT 
    @Columns = 
        STRING_AGG(
            'MAX(CASE [Server] WHEN ' + QUOTENAME([Server], '''') + ' THEN [Tape] END) AS ' + QUOTENAME([Server]), 
            ','
        ) WITHIN GROUP(ORDER BY [Server]) 
FROM 
(
    SELECT [Server] FROM T GROUP BY [Server]
) S;

SET @Sql =
    'SELECT ' + @Columns + ' FROM 
        (SELECT [Server], [Tape], ROW_NUMBER() OVER (PARTITION BY [SERVER] ORDER BY [Server]) as RN FROM T) S 
    GROUP BY RN'

EXEC(@Sql);

Note: STRING_AGG() is supported on SQL Server 2017 and later.