SQL-每行一項

Question

我有一個名為Registers的表，包含3個字段，如下所示：

Select PersonID, RegisterID, Status from Registers

PersonID    RegisterID  Status
-------------------------------
3049518     14467       A
3049518     14467       B
3049518     14467       C
3049518     32445       A
3049518     32445       B
3049518     32445       C

是否有一種簡單的方法可以在一行上顯示每個寄存器及其狀態？ 例如

PersonID    RegisterID  Status1 Status2 Status3
------------------------------------------------
3049518     14467       A       B       C
3049518     32445       A       B       C

提前致謝。

Answer 1

你可以做這樣的事情

  SELECT SUBSTRING((SELECT   ',' + CONVERT(VARCHAR , Status)       
                                                            FROM DBO.Registers WITH (NOLOCK)

                                                            FOR XML PATH('')),2,20000)),'')

否則提供sql小提琴，以便我編寫完整的查詢

Answer 2

如果您有固定數量的狀態，並且知道狀態值，那么使用以下代碼即可獲得所需的內容。

CREATE TABLE #Register(PersonID int, RegisterID int, Stat varchar)

INSERT INTO #Register (PersonID,RegisterID,Stat) VALUES
('3049518','14467','A'),
('3049518','14467','B'),
('3049518','14467','C'),
('3049518','32445','A'),
('3049518','32445','B'),
('3049518','32445','C')

SELECT PersonID
    ,RegisterID
    ,MAX(A) 'A'
    ,MAX(B) 'B'
    ,MAX(C) 'C'
FROM (
    SELECT PersonID
        ,RegisterID
        ,CAST(CASE 
                WHEN r.stat = 'A'
                    THEN 'A'
                ELSE NULL
                END AS VARCHAR) AS 'A'
        ,CAST(CASE 
                WHEN r.stat = 'B'
                    THEN 'B'
                ELSE NULL
                END AS VARCHAR) AS 'B'
        ,CAST(CASE 
                WHEN r.stat = 'C'
                    THEN 'C'
                ELSE NULL
                END AS VARCHAR) AS 'C'
    FROM #Register r
    GROUP BY PersonID
        ,RegisterID
        ,Stat
    ) q
GROUP BY q.PersonID
    ,q.RegisterID

該代碼假設每種狀態下每人只有一條記錄。

輸出

如果狀態值不是固定的，並且您不知道它們是什么，則可以在SQL Server中使用以下命令：

CREATE TABLE #Register(PersonID int, RegisterID int, Stat varchar)

INSERT INTO #Register (PersonID,RegisterID,Stat) VALUES
('3049518','14467','A'),
('3049518','14467','B'),
('3049518','14467','C'),
('3049518','32445','A'),
('3049518','32445','B'),
('3049518','32445','C')


DECLARE @queryPart1 NVARCHAR(MAX)
    ,@queryPart2 NVARCHAR(MAX)
    ,@colHeader NVARCHAR(MAX)
    ,@query NVARCHAR(MAX)

SET @queryPart1 = 'SELECT PersonID,RegisterID'
SET @queryPart2 = 'FROM (SELECT PersonID,RegisterID'
SET @query = ''

DECLARE Stat_Cursor CURSOR
FOR
SELECT DISTINCT (STAT)
FROM #Register r

OPEN Stat_Cursor;

FETCH NEXT
FROM Stat_Cursor
INTO @colHeader

WHILE @@FETCH_STATUS = 0
BEGIN
    SET @queryPart1 = @queryPart1 + ',MAX(''' + @colHeader + ''') ''' + @colHeader + ''''
    SET @queryPart2 = @queryPart2 + ',CAST(CASE WHEN r.stat = ''' + @colHeader + ''' THEN ''' + @colHeader + ''' ELSE NULL END AS VARCHAR) AS ''' + @colHeader + ''''

    FETCH NEXT
    FROM Stat_Cursor
    INTO @colHeader
END;

CLOSE Stat_Cursor;

DEALLOCATE Stat_Cursor;

SET @query = @queryPart1 + @queryPart2 + 'FROM #Register r GROUP BY PersonID ,RegisterID,Stat) q'

PRINT @query
GO

Answer 3

如果使用Oracle，這是一個解決方案：

    select * from ( 
    select PersonID,RegisterID, Status
   from test t
)
pivot 
(
   count(Status)
   for Status in ('A' as "Status1",'B' "Status2",'C' "Status3")
)
order by 1

SQLFiddle