SQL Server 2008中選擇兩個表

Question

我有兩個表連接，第一個是這樣的：

[比較]

• ID（INT）
• Car_Id1（INT）
• Car_Id2（INT）
• 蛞蝓（字符串）
• 時間戳

第二個：

[VehicleSpecs]

• ID（INT）
• 年份（INT）
• 製作（字符串）
• 模型（字符串）

我有這個疑問

SELECT TOP 100 * 
FROM [Comparsions] 
WHERE 
ORDER BY [TimeStamp] 

它返回最新的100條記錄，但我需要從第二臺這樣的替換Car_Id1和Car_Id2的信息：Car_Id1 -> [Year + Make + Model]

Answer 1

所以你需要什麼是二INNER JOIN s對VehicleSpecs表，每個Car_Id1和Car_Id2一個。我把它們別名爲car1, car2。

SELECT TOP 100 
    c.Id, 
    c.Slug, 
    c.TimeStamp, 
    /* Select the relevant columns from *both* of the joined tables */ 
    /* And give each column an alias to differentiate it from the other */ 
    car1.Year AS car1Year, 
    car1.Make AS car1Make, 
    car1.Model AS car1Model, 
    car2.Year AS car2Year, 
    car2.Make AS car2Make, 
    car2.Model AS car2Model 
FROM 
    Comparisons c 
    /* Join first against VehicleSpecs for Car_Id1 */ 
    INNER JOIN VehicleSpecs car1 ON c.Car_Id1 = car1.Id 
    /* Then once more for Car_Id2 */ 
    INNER JOIN VehicleSpecs car2 ON c.Car_Id2 = car2.Id 
ORDER BY c.TimeStamp 

你說你想要的最新，所以我想你實際上意味着對時間戳使用降序排列：

ORDER BY c.TimeStamp DESC 

Answer 2

加入對第二個表兩次：

select top 100 
    c.Id, c.Slug, c.TimeStamp, 
    s1.Year as Car1_Year, s1.Make as Car1_Make, s1.Model as Car1_Model, 
    s2.Year as Car2_Year, s2.Make as Car2_Make, s2.Model as Car2_Model 
from Comparsions c 
inner join VehicleSpecs s1 on s1.Id = c.Car_Id1 
inner join VehicleSpecs s2 on s2.Id = c.Car_Id2 
order by c.TimeStamp desc 

（注意：您可能需要將表格名稱更改爲Comparisons。）