display result as 1 row in transposed/pivoted result of sub query in SQL Compact edition

问题

I have a table MonitorLocationDetails which looks like below

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

I should get the rows of LocDescription and transpose it like pivot in sql server other versions. PIVOT not available in sql compact versions. The Pivoting should be based on the result of a sub query

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

This works ok.

I have so far :

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

which yields:

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

empty spaces even with DISTINCT used.. i did not give names for columns, cause i need the result just as follows in 1 row

MP-1 descr   Main Gate descr    MP-2 descr

Any one would you please assist?

回答1:

You're close. You just have to put MAX before your 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

You could also simplify your query:

;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')

来源：https://stackoverflow.com/questions/28755547/display-result-as-1-row-in-transposed-pivoted-result-of-sub-query-in-sql-compact

标签

pivot

sql-server-ce-3.5