我正在搜索，但找不到解决问题的方法。 我有一张包含这些数据的表格（比如 T1）：
| SampleCode | Name | Content |
|---|---|---|
| # | 1 | A# |
| # | 2 | B# |
| # | 3 | C# |
| @ | 1 | A@ |
| @ | 2 | B@ |
| @ | 3 | C@ |
所以我需要一个选择查询，结果是：
| Column 1 | Column 2 | Column 3 |
|---|---|---|
| SampleCode | # | @ |
| Name.1 | A# | A@ |
| Name.2 | B# | B@ |
| Name.3 | C# | C@ |
有人有提示吗？
谢谢
法比奥
【问题讨论】：
查看本文中的 2 个选项：https://www.sqlshack.com/multiple-options-to-transposing-rows-into-columns/
如果使用 TSQL，您可以使用 TRANSPOSE 语句。或者，您可以使用游标/循环和动态 SQL 创建结果集。
我不敢相信我敲定了这个...也许我这样做只是为了看看我是否可以。它又长又复杂，并且使用了几个循环。我认为你应该重新评估你正在尝试做的事情。这不能在视图中运行。您将不得不放入一个函数或存储过程。您可能需要评估临时表名称以查看它们是否与您的环境兼容。此外，由于临时表名称不是唯一的，因此您不能运行多个实例；如果要运行多个实例，则必须将唯一标识符添加到临时表中的列或临时表名称。这是完全动态的……您不必提前知道需要多少列。
--**************************************************
--Header area... sample data and temp tables.
--**************************************************
--Clean up sample and result tables if they exist.
IF OBJECT_ID(N'tempdb..#T1') IS NOT NULL
DROP TABLE #T1;
IF OBJECT_ID(N'tempdb..#ResultsTemp') IS NOT NULL
DROP TABLE #ResultsTemp;
IF OBJECT_ID(N'tempdb..#codeTable') IS NOT NULL
DROP TABLE #codeTable;
--For Debugging.
DECLARE @debug int = 1; --0=no debug, 1=show debug messages, do not exec all SQL statements.
--Table var to hold sample data.
CREATE TABLE #T1 (
SampleCode nvarchar(50),
[Name] nvarchar(50),
Content nvarchar(50),
row_num int
);
--Load Sample Data.
INSERT INTO #T1 (SampleCode, [Name], Content)
VALUES
('#', '1', 'A#')
, ('#', '2', 'B#')
, ('#', '3', 'C#')
, ('@', '1', 'A@')
, ('@', '2', 'B@')
, ('@', '3', 'C@')
;
--**********END HEADER**********
--Number the rows so we can loop over them.
UPDATE #T1
SET row_num = newT1.row_num
FROM
(
SELECT t12.SampleCode
, t12.[Name]
, T12.Content
, ROW_NUMBER()OVER(ORDER BY SampleCode, [Name], Content) as row_num
FROM #T1 as t12
) AS newT1
WHERE #T1.SampleCode = newT1.SampleCode
AND #T1.[Name] = newT1.[Name]
AND #T1.Content = newT1.Content
;
SELECT * FROM #T1; --Debugging... just show the contents of #T1 after adding row_num
--Create temp table to load results.
CREATE TABLE #ResultsTemp (
Column1 nvarchar(50)
);
--Create some variable to track looping (without a cursor).
DECLARE @loopCount int = 1;
DECLARE @maxLoops int = (SELECT COUNT(DISTINCT SampleCode) FROM #T1);
DECLARE @sql nvarchar(512);
--Add columns to #ResultsTable dynamically
WHILE (@loopCount <= (@maxLoops))
BEGIN
SET @sql = 'ALTER TABLE #ResultsTemp ADD ' + QUOTENAME('Column' + CAST((@loopCount + 1) as nvarchar)) + ' nvarchar(50) NULL';
IF (@debug = 1) PRINT @sql;
EXEC (@sql);
SET @loopCount = @loopCount + 1;
END
--************************************************************
--SECTION FOR INSERTING FIRST ROW for "SampleCode"
--************************************************************
--Vars for tracking the SampleCode variations processed.
DECLARE @sampleLoop int = 1;
DECLARE @sampleCount int = (SELECT COUNT(DISTINCT SampleCode) FROM #T1);
CREATE TABLE #codeTable (
SampleCode nvarchar(50)
, row_num int
);
--Create a list of unique SampleCodes to loop over.
INSERT INTO #codeTable (SampleCode)
SELECT DISTINCT
SampleCode
FROM #T1;
UPDATE #codeTable
SET row_num = newCT.row_num
FROM
(
SELECT ct2.SampleCode
, ROW_NUMBER()OVER(ORDER BY SampleCode) as row_num
FROM #codeTable as ct2
) AS newCT
WHERE #codeTable.SampleCode = newCT.SampleCode
;
SET @sql = 'INSERT INTO #ResultsTemp (Column1) SELECT ''SampleCode''';
IF (@debug = 1) PRINT @sql;
EXEC (@sql);
WHILE (@sampleLoop <= @sampleCount)
BEGIN
SET @sql = 'UPDATE #ResultsTemp SET Column' + CAST(@SampleLoop + 1 as nvarchar) + '=(SELECT TOP 1 SampleCode FROM #codeTable WHERE row_num = ' + CAST(@sampleLoop as nvarchar) + ');';
IF (@debug = 1) PRINT @sql;
EXEC (@sql);
SET @sampleLoop = @sampleLoop + 1;
END
IF (@debug = 1) SELECT * FROM #ResultsTemp;
--**********END SECTION**********
--**************************************************
--SECTION FOR INSERTING THE REST OF THE CONTENT DATA
--**************************************************
--Vars for tracking number of rows processed from T1.
SET @loopCount = 1;
SET @maxLoops = (SELECT MAX(row_num) FROM #T1);
--Loop over each row in T1.
WHILE (@loopCount <= @maxLoops)
BEGIN
--Create a name for this row.
DECLARE @nameRaw nvarchar(50) = (SELECT TOP 1 [Name] FROM #T1 WHERE row_num = @loopCount);
DECLARE @codeNum nvarchar(50) = (
SELECT TOP 1 ct.row_num
FROM #T1 as t
INNER JOIN #codeTable as ct
ON ct.SampleCode = t.SampleCode
WHERE t.row_num = @loopCount);
DECLARE @name nvarchar(50) = 'Name.' + @nameRaw;
--First insert a row for this Name... if not already in the list.
SET @sql = 'INSERT INTO #ResultsTemp (Column1)
SELECT ''Name.'' + t.[Name]
FROM #T1 as t
LEFT OUTER JOIN #ResultsTemp as rt
ON rt.Column1 = ''' + @name + '''
WHERE t.row_num = ' + CAST(@loopCount as nvarchar) + '
AND rt.Column1 IS NULL;';
IF (@debug = 1) PRINT @sql;
EXEC (@sql);
--Update this Name row with the "content".
SET @sql = 'UPDATE rt
SET Column' + CAST(@codeNum + 1 as nvarchar) + '=t.Content
FROM #ResultsTemp as rt
INNER JOIN #T1 as t
ON t.row_num = ' + CAST(@loopCount as nvarchar) + '
AND t.[Name] = ''' + @nameRaw + '''
WHERE rt.Column1 = ''' + @name + ''';';
IF (@debug = 1) PRINT @sql;
EXEC (@sql);
SET @loopCount = @loopCount + 1;
END
--Show everything in the temp Results table.
SELECT *
FROM #ResultsTemp;
下一个选项不是动态的。您必须知道需要多少列，然后您可以将“Column3”代码复制到任何新列。您必须更改列名并更新“Select TOP 1”语句，如您要复制的每个新列的注释。
WITH CodeTable AS (
SELECT DISTINCT t.SampleCode
FROM #T1 as t
)
SELECT DISTINCT
'Name.' + [Name]
, (
SELECT TOP 1 Content
FROM #T1 as t2
WHERE t2.SampleCode = (
SELECT TOP 1 SampleCode
FROM CodeTable as ct
ORDER BY SampleCode
)
AND t2.[Name] = t.[Name]
) as Column2
, (
SELECT TOP 1 Content
FROM #T1 as t2
WHERE t2.SampleCode = (
SELECT TOP 1 SampleCode
FROM CodeTable as ct
WHERE ct.SampleCode NOT IN (
SELECT TOP 1 SampleCode --Update the TOP 1 to be TOP [number of previous columns]
FROM CodeTable as ct2
ORDER BY ct2.SampleCode
)
ORDER BY ct.SampleCode
)
AND t2.[Name] = t.[Name]
) as Column3
FROM #T1 as t
该解决方案来自我发布的链接。同样，您必须知道所需的列数，并且它没有您指定的通用列名。但是，如果您重新考虑您的输出，这是另一种解决方案。
--Use PivotTable.
SELECT *
FROM
(
SELECT [Name], Content
FROM #T1
) AS SourceTable PIVOT(MAX(Content) FOR [Content] IN([A#],
[A@]
)) AS PivotTable;
【讨论】：
数据透视表可以解决您的问题：
DECLARE @T TABLE (SampleCode sysname, Name sysname, Content sysname)
INSERT @T (SampleCode, Name, Content)
VALUES
('#', '1', 'A#'),
('#', '2', 'B#'),
('#', '3', 'C#'),
('@', '1', 'A@'),
('@', '2', 'B@'),
('@', '3', 'C@')
SELECT CONCAT('Name.', PIVOTTABLE.Name), [PIVOTTABLE].[#], [PIVOTTABLE].[@]
FROM
(
SELECT * FROM @T AS t
) AS SOURCE
PIVOT (
MAX(Content)
FOR SampleCode IN ([#], [@])
) AS PIVOTTABLE
当然，这是您在问题中提供的解决方案。
当列太多而无法手动写下时，请使用动态查询，唯一需要生成的部分是 FOR 表达式中的值和 SELECT 中的相同值
【讨论】：