SQL联接并将1列放入2列

我有两张表，如上所示。我想创建一个select语句，该语句将产生以下结果：

基本上，我想加入'Model'和'Num'列，并带来'Val'值，但根据'Ver'将其分为两列

SELECT 'a' as Model ,'1' as Num ,'v1' as Ver ,'9' as val INTO #RefTbl UNION ALL
SELECT 'a','2','v1','10' UNION ALL
SELECT 'a','3','v1','11' UNION ALL
SELECT 'a','1','v2','5' UNION ALL
SELECT 'a','2','v2','6' UNION ALL
SELECT 'a','3','v2','7' UNION ALL
SELECT 'b','1','v1','20' UNION ALL
SELECT 'b','1','v2','21' UNION ALL
SELECT 'b','2','v1','25' UNION ALL
SELECT 'b','2','v2','26'


SELECT '519' as ID,'a' as Model,'1' as Num INTO #OrderTbl UNION ALL
SELECT '5616','a','3' UNION ALL
SELECT '871','b','1' 


-- failed attempt
SELECT o.*, '' as v1_val, '' as v2_val FROM #OrderTbl as o left join #RefTbl as r on o.Model = r.Model and o.Num = r.Num 

---

您可以加入并执行条件聚合：

select
    d.ID,
    d.Model,
    d.Num,
    max(case when r.Ver = 'val1' then Val end) V1_Val,
    max(case when r.Ver = 'val2' then Val end) V2_Val
from DataTbl d
inner join ReferenceTbl r 
    on  r.Model = d.Model
    and r.Num = d.Num
group by
    d.ID,
    d.Model,
    d.Num

或者，您可以加入两次—根据您的数据集，这可能（也可能不）执行得更好：

select
    d.ID,
    d.Model,
    d.Num,
    r1.Val V1_Val,
    r2.Val V2_Val
from DataTbl d
left join ReferenceTbl r1 
    on  r1.Model = d.Model
    and r1.Num = d.Num
    and r1.Ver = 'val1'
left join ReferenceTbl r2
    on  r2.Model = d.Model
    and r2.Num = d.Num
    and r2.Ver = 'val2'

---

Case+groupby在大多数数据库系统上都很好用

使用SQL Server PIVOT的备选答案（供参考）

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@GMB，我试过了，但没有达到预期效果，你能提供提琴吗？@ϻᴇᴛᴀʟ：我认为问题的第一张图片中有一个小问题，第二条记录（id为5616）的数字应该是2而不是3。@GMB，这让我想得更复杂了。请更新您的问题以匹配GMB的答案

WITH RefTbl AS (
    SELECT 'a' as Model ,'1' as Num ,'v1' as Ver ,'9' as val UNION ALL
    SELECT 'a','2','v1','10' UNION ALL
    SELECT 'a','3','v1','11' UNION ALL
    SELECT 'a','1','v2','5' UNION ALL
    SELECT 'a','2','v2','6' UNION ALL
    SELECT 'a','3','v2','7' UNION ALL
    SELECT 'b','1','v1','20' UNION ALL
    SELECT 'b','1','v2','21' UNION ALL
    SELECT 'b','2','v1','25' UNION ALL
    SELECT 'b','2','v2','26'), 
OrderTbl AS (
    SELECT '519' as ID,'a' as Model,'1' as Num UNION ALL
    SELECT '5616','a','3' UNION ALL
    SELECT '871','b','1' 
)
SELECT Id, Model, Num AS Model, [v1] AS v1_Val, [v2] as v2_Val
FROM  
    (SELECT o.id, r.Model, r.Num, r.val, r.ver from OrderTbl as o 
     left join RefTbl as r on o.Model = r.Model and o.Num = r.Num) AS SourceTable  
PIVOT  
(MAX(val) FOR ver IN ([v1], [v2])) AS PivotTable;  

Id      Model   Model   v1_Val  v2_Val
519     a       1       9       5
5616    a       3       11      7
871     b       1       20      21