Question

此问题从one开始。以下Sql工作正常：

IF OBJECT_ID('tempdb..#Source') IS NOT NULL DROP TABLE #Source
IF OBJECT_ID('tempdb..#Aim') IS NOT NULL DROP TABLE #Aim

CREATE TABLE #Source
(
    ColumnName NVARCHAR(10),
    ColumnValue NVARCHAR(10),
    Id INT
)

CREATE TABLE #Aim
(
    Id INT,
    Column1 NVARCHAR(10),
    Column2 NVARCHAR(10),
    Column3 NVARCHAR(10)
)

INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column1', 'Value1', 1);
INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column2', 'Value1', 1);
INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column1', 'Value2', 2);
INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column1', 'Value4', 3);
INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column3', 'Value1', 3);
INSERT INTO #Source (ColumnName, ColumnValue, Id) VALUES ('Column3', 'Value3', 4);

INSERT INTO #Aim (Id, Column1, Column2, Column3) VALUES (1, 'Value1', 'Value1', NULL)
INSERT INTO #Aim (Id, Column1, Column2, Column3) VALUES (2, 'Value2', NULL, NULL)
INSERT INTO #Aim (Id, Column1, Column2, Column3) VALUES (3, 'Value4', NULL, 'Value1')
INSERT INTO #Aim (Id, Column1, Column2, Column3) VALUES (4, NULL, NULL, 'Value3')

DECLARE @col_list VARCHAR(max) = (SELECT Quotename(ColumnName) + ','
   FROM   #Source
   GROUP  BY ColumnName
   ORDER  BY ColumnName
   FOR xml path('')) -- To create the dynamic column list 

SET @col_list = LEFT(@col_list, Len(@col_list) - 1) -- To remove the leading comma 

DECLARE @sql NVARCHAR(max)

SELECT @sql = 'select * from #Source
pivot (max(ColumnValue) for ColumnName in ('
              + @col_list + '))pv'

EXEC Sp_executesql @sql  -- Execute the dynamic sql

挑战在于，如果少于n列，我想添加虚拟列。所以对于n = 5，我想实现这个输出：

Id  Column1 Column2 Column3 Dummy4  Dummy5
1   Value1  Value1  NULL    NULL    NULL
2   Value2  NULL    NULL    NULL    NULL
3   Value4  NULL    Value1  NULL    NULL
4   NULL    NULL    Value3  NULL    NULL

理想情况下，n可以作为变量吗？

Answer 1

这是一种方式

╔════╦═════════╦═════════╦═════════╦════════╦════════╗
║ Id ║ Column1 ║ Column2 ║ Column3 ║ dummy4 ║ dummy5 ║
╠════╬═════════╬═════════╬═════════╬════════╬════════╣
║  1 ║ Value1  ║ Value1  ║ NULL    ║ NULL   ║ NULL   ║
║  2 ║ Value2  ║ NULL    ║ NULL    ║ NULL   ║ NULL   ║
║  3 ║ Value4  ║ NULL    ║ Value1  ║ NULL   ║ NULL   ║
║  4 ║ NULL    ║ NULL    ║ Value3  ║ NULL   ║ NULL   ║
╚════╩═════════╩═════════╩═════════╩════════╩════════╝

<强>结果：

{{1}}

添加动态占位符列以动态调整数据

1 个答案: