条件聚合引用表而不是手动输入(Conditional aggregation referencing table instead of manual entry)

 我先前问了一个关于条件聚合的问题。 SQL Transform Crosstab Pivot和答案很棒！ 但是，我需要对此进行扩展。 
 
 当时的解决方案是以下查询： 
 
SELECT
    Item,
    [X] = MAX(CASE WHEN [Columns] = 'X' THEN Result END),
    [Y] = MAX(CASE WHEN [Columns] = 'Y' THEN Result END),
    [Z] = MAX(CASE WHEN [Columns] = 'Z' THEN Result END)
FROM thisTable
GROUP BY Item
 
 问题：我现在有一个表格TEST其中W，X，Y，Z为行。 而不是向查询添加另一行（ [W] = MAX(CASE WHEN [Columns] = 'W' THEN Result END) ），可以重写上面的查询以引用值的表吗？ 
 
 原因是因为我预计不仅仅有W，X，Y，Z，并且希望将来避免在此查询中添加更多行。 

I asked a question previously on conditional aggregation. SQL Transform Crosstab Pivot and the answer was great! However, I need to expand on this.
 
The solution at the time was the following query:
 
SELECT
    Item,
    [X] = MAX(CASE WHEN [Columns] = 'X' THEN Result END),
    [Y] = MAX(CASE WHEN [Columns] = 'Y' THEN Result END),
    [Z] = MAX(CASE WHEN [Columns] = 'Z' THEN Result END)
FROM thisTable
GROUP BY Item
 
Question: I now have a table TEST with W, X, Y, Z in rows. Instead of adding another line ([W] = MAX(CASE WHEN [Columns] = 'W' THEN Result END)) to the query, can the query above be re-written to refer to the table for the values? 
 
The reason is because I anticipate that there will more than just W, X, Y, Z and want to avoid adding more lines to this query in the future.

原文：https://stackoverflow.com/questions/38109330