pivot - 在 SQL Compact 版本的子查询的转置/透视结果中将结果显示为 1 行

Question

我有一张MonitorLocationDetails如下所示的表格

lid LoclColumn  LocDescription
1   MP1         MP-1 descr
2   MP2         MP-2 descr
3   MainGate    Main Gate descr 

我应该在其他版本的 sql server 中获取行LocDescription并将其转置，就像 pivot 一样。PIVOT 在 sql compact 版本中不可用。透视应该基于子查询的结果

SELECT LocColumn,LocDescription 
FROM MonitorLocationDetails 
WHERE LocColumn IN ('MP1','MP2','MainGate')

这工作正常。

我到目前为止：

SELECT DISTINCT 
    (CASE WHEN P.LocColumn = 'MP1' THEN P.LocDescription ELSE '' END), 
    (CASE WHEN P.LocColumn = 'MainGate' THEN P.LocDescription ELSE '' END), 
    (CASE WHEN P.LocColumn = 'MP2' THEN P.LocDescription ELSE '' END) 
FROM (
    SELECT LocColumn,LocDescription 
    FROM MonitorLocationDetails 
    WHERE LocColumn IN ('MP1','MP2','MainGate')
) P

产生：

column1     column2     column3
                        MP-2 descr
            Main Gate desc  
MP-1 descr      

即使使用了 DISTINCT 也有空格.. 我没有给出列的名称，因为我需要在 1 行中如下所示的结果

MP-1 descr   Main Gate descr    MP-2 descr

有没有人请你帮忙？

Answer 1

你很近。你只需要MAX在你的CASE expression.

SELECT 
    MAX(CASE WHEN P.LocColumn = 'MP1' THEN P.LocDescription ELSE '' END), 
    MAX(CASE WHEN P.LocColumn = 'MainGate' THEN P.LocDescription ELSE '' END), 
    MAX(CASE WHEN P.LocColumn = 'MP2' THEN P.LocDescription ELSE '' END) 
FROM (
    SELECT LocColumn,LocDescription 
    FROM MonitorLocationDetails 
    WHERE LocColumn IN ('MP1','MP2','MainGate')
) P

---

您还可以简化查询：

;WITH MonitorLocationDetails(lid, LocColumn, LocDescription) AS(
    SELECT 1, 'MP1', 'MP-1 Descr' UNION ALL
    SELECT 2, 'MP2', 'MP-2 Descr' UNION ALL
    SELECT 3, 'MainGate', 'MainGate Descr'
)
SELECT
    MAX(CASE WHEN LocColumn = 'MP1' THEN LocDescription ELSE '' END), 
    MAX(CASE WHEN LocColumn = 'MainGate' THEN LocDescription ELSE '' END), 
    MAX(CASE WHEN LocColumn = 'MP2' THEN LocDescription ELSE '' END) 
FROM MonitorLocationDetails 
WHERE LocColumn IN ('MP1','MP2','MainGate')