SQL遍歷列並將結果插入到臨時表中

Question

我有一個臨時#CarIDs的汽車ID列表

CREATE TABLE #CarIDs(
[CARID] [nvarchar] (60) NULL,
[Type] [nvarchar] (20) NULL,
[Flag] [nvarchar] (30) NULL) GO

INSERT INTO #CarIDs (CARID, Type, Flag) VALUES ('1111','',''), ('2222','',''), ('3333','',''), ('4444','',''), ('5555','',''), ('6666','','')

這給了我SELECT * FROM #CarIDs

+-------+-------+--------+
| CARID | Type  |  Flag  |
+-------+-------+--------+
|  1111 |       |        |
|  2222 |       |        |      
|  3333 |       |        |
|  4444 |       |        |
|  5555 |       |        |
|  6666 |       |        |
+-------+-------+--------+

如何遍歷下表（CarHierarchy）以找出每個CARID屬於哪種模型類型，然后插入到臨時表中？

+-------+-------+-------+
| Jeep  |Holden | Ford  |
+-------+-------+-------+
| 1111  |2222   | 3333  | 
| 4444  |6666   | 5555  |        
+-------+-------+-------+

我希望結果是#CarIDs：

+-------+-------+
| CARID | Type  | 
+-------+-------+
|  1111 |Jeep   |  
|  2222 |Holden |    
|  3333 |Ford   |     
|  4444 |Jeep   |    
|  5555 |Ford   |    
|  6666 |Holden |     
+------+--------+

Answer 1

您需要UNPIVOT第一#CarHierarchy表，然后做一個JOIN上#CarIDs表以獲得正確的類型：

-- Unpivot the #CarHierarchy table using CROSS APPLY
WITH CteCarHierarchy AS(
    SELECT *
    FROM #CarHierarchy
    CROSS APPLY( VALUES
        (Jeep, 'Jeep'),
        (Holden, 'Holden'),
        (Ford, 'Ford')
    )t (CARID, Type)
)
SELECT
    ci.CARID,
    Type = cch.Type,
    ci.Flag
FROM #CarIDs ci
INNER JOIN CteCarHierarchy cch
    ON cch.CARID = ci.CARID

---

UPDATE語句：

在線演示

WITH CteCarHierarchy AS(
    SELECT *
    FROM #CarHierarchy
    CROSS APPLY( VALUES
        (Jeep, 'Jeep'),
        (Holden, 'Holden'),
        (Ford, 'Ford')
    )t (CARID, Type)
)
UPDATE ci
    SET ci.Type = cch.Type
FROM #CarIDs ci
INNER JOIN CteCarHierarchy cch
    ON cch.CARID = ci.CARID

參考：

• Dwain Camps的UNPIVOT（SQL Spackle）的替代方法（更好？）