SQL Server 2005-动态PIVOT查询

Question

关于PIVOT查询问题，我需要您的帮助。场景是我有一个投票系统。由3张表组成。选举，候选人，投票。

PIVOT与PIVOTing相关，候选名称为列，并具有VOTE数据作为数据。

到目前为止，我已经尝试过了，但没有成功，我陷入了混乱：（

CREATE TABLE  #MYELECTIONS (E_POSITION_CODE INT, E_POSITIONNAME VARCHAR(50))
    INSERT INTO #MYELECTIONS VALUES (147,'MANAGER')
    INSERT INTO #MYELECTIONS VALUES (148,'CHEF')
    INSERT INTO #MYELECTIONS VALUES (149,'WAITER')
CREATE TABLE  #MYCANDIDATES (C_CANDIDATE_CODE INT, 
                          C_CANDIDATENAME VARCHAR (50), C_POSITION_CODE INT)
INSERT INTO #MYCANDIDATES VALUES (100,'TOM CRUISE', 147)
INSERT INTO #MYCANDIDATES VALUES (101,'MICKY MOUSE', 147)
INSERT INTO #MYCANDIDATES VALUES (103,'DONALD DUCK', 147)
INSERT INTO #MYCANDIDATES VALUES (100,'TOM CRUISE', 148)
CREATE TABLE  #MYVOTES (V_POSITION_CODE INT, 
                        V_CANDIDATE_CODE INT, VOTINGPREFERENCE SMALLINT)
INSERT INTO #MYVOTES VALUES (147,100,1)
INSERT INTO #MYVOTES VALUES (147,100,1)
INSERT INTO #MYVOTES VALUES (147,100,1)
INSERT INTO #MYVOTES VALUES (147,100,1)
INSERT INTO #MYVOTES VALUES (147,101,1)
INSERT INTO #MYVOTES VALUES (147,101,1)
INSERT INTO #MYVOTES VALUES (147,103,1)
INSERT INTO #MYVOTES VALUES (148,100,1)
INSERT INTO #MYVOTES VALUES (148,100,1)
DECLARE @DynamicPivotQuery  AS NVARCHAR(MAX)
DECLARE @ColumnName         AS NVARCHAR(MAX)
DECLARE @MyPositionCode     AS INT
SET @MyPositionCode = 147
DECLARE @MyOutput           AS NVARCHAR(MAX)
--Get distinct values of the PIVOT Column 
SELECT @ColumnName = ISNULL(@ColumnName + ',','') 
                + QUOTENAME(C_CANDIDATENAME)
FROM (SELECT TOP 100 PERCENT C_CANDIDATENAME 
    FROM #MYCANDIDATES 
    WHERE C_POSITION_CODE = @MyPositionCode 
    ORDER BY C_CANDIDATE_CODE) AS C_CANDIDATENAME

--Prepare the `PIVOT` query using the dynamic sql
SET @DynamicPivotQuery = 
  N'SELECT  ROW_NUMBER() OVER (ORDER BY E_POSITIONNAME) AS Idnum,    
  E_POSITIONNAME AS [Position Name], ' + @ColumnName + '
  FROM  #MYVOTES 
  INNER JOIN #MYELECTIONS 
  ON (#MYVOTES.V_POSITION_CODE = #MYELECTIONS.E_POSITION_CODE)
    PIVOT(SUM(VOTINGPREFERENCE))
      FOR C_CANDIDATENAME IN (' + @ColumnName + ') AS PVTTable
  WHERE #MYELECTIONS.E_POSITION_CODE = 147'
--Execute the Dynamic Pivot Query
EXEC sp_executesql  @DynamicPivotQuery, 
                    @MyOutput = @MyOutput OUTPUT
SELECT @MyOutput
DROP TABLE #MYELECTIONS
DROP TABLE #MYCANDIDATES
DROP TABLE #MYVOTES

它必须是一个动态的PIVOT作为候选人名称，我想Pivot作为列，可以是动态的，这取决于一个选举职位有多少候选人。

上述所需的输出如下：-

选择@MyPositionCode=147

Idnum   Position_Name   TOM CRUISE  MICKY MOUSE  DONALD DUCK...
1       MANAGER         4           2            1           

选择@MyPositionCode=148

Idnum   Position_Name   TOM CRUISE  MICKY MOUSE  DONALD DUCK...
1       CHEF            2           0            0

Answer 1

试试这个

DECLARE @MyPositionCode     AS INT
SET @MyPositionCode = 147

声明用于选择动态列的变量

DECLARE @DynamicPivotQuery  AS NVARCHAR(MAX)
DECLARE @ColumnName         AS NVARCHAR(MAX)

DECLARE @cols NVARCHAR (MAX)
SELECT @cols = COALESCE (@cols + ',[' + C_CANDIDATENAME + ']', '[' + C_CANDIDATENAME + ']')
               FROM    
               (
                    SELECT TOP 100 PERCENT C_CANDIDATENAME 
                    FROM #MYCANDIDATES 
                    WHERE C_POSITION_CODE = @MyPositionCode 
                    ORDER BY C_CANDIDATE_CODE
                ) PV 
               ORDER BY C_CANDIDATENAME desc

如果您想用零替换NULL

DECLARE @NulltoZeroCols NVARCHAR (MAX)
SELECT @NullToZeroCols = SUBSTRING((SELECT ',ISNULL(['+C_CANDIDATENAME+'],0) AS ['+C_CANDIDATENAME+']' 
FROM 
(
    SELECT TOP 100 PERCENT C_CANDIDATENAME 
    FROM #MYCANDIDATES 
    WHERE C_POSITION_CODE = @MyPositionCode 
    ORDER BY C_CANDIDATE_CODE
)TAB  
ORDER BY C_CANDIDATENAME desc FOR XML PATH('')),2,8000)

现在动态调整它。我已经在中编写了逻辑

DECLARE @query NVARCHAR(MAX)
SET @query = '-- You can apply ROW_NUMBER() here which is the data after pivot 
              SELECT ROW_NUMBER() OVER (ORDER BY E_POSITIONNAME) AS Idnum,
              ,E_POSITIONNAME,'+@NullToZeroCols+'  
              FROM 
             (           
                -- Select data before pivot      
                SELECT  TOP 100 PERCENT ME.E_POSITIONNAME,MC.C_CANDIDATENAME,
                COUNT(MC.C_CANDIDATENAME) OVER(PARTITION BY ME.E_POSITIONNAME,MC.C_CANDIDATENAME) CNT
                FROM #MYELECTIONS ME
                JOIN #MYCANDIDATES MC ON ME.E_POSITION_CODE=MC.C_POSITION_CODE
                JOIN #MYVOTES MV ON MC.C_CANDIDATE_CODE=MV.V_CANDIDATE_CODE
                AND MV.V_POSITION_CODE=MC.C_POSITION_CODE
                WHERE MC.C_POSITION_CODE = ' + CAST(@MyPositionCode AS VARCHAR(30)) + '
             ) x
             PIVOT 
             (
                 MIN(CNT)
                 FOR C_CANDIDATENAME IN (' + @cols + ')
            ) p
            ;' 
EXEC SP_EXECUTESQL @query

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