SQL加入问题

Question

我有一个关于SQL Join的有趣问题.我有2个表,示例如下:

表1:ID(int),值(字符串)表
2:ID(int),ForeignID(int),(Value)

Table2中的字段ForeignID是Table1中ID的外键.对于Table1中的给定条目,我在Table2中有多个条目,如下所示:

Table1:  
ID, Value  
0, "Hello World"  
1, "Bonjour"  

Table2:  
ID, ForeignID, Value  
0, 0, "First entry"  
1, 0, "Second entry"  
2, 1, "Third entry"  

如果我做一个内部连接,如

SELECT Table1.Value, Table2. Value FROM 
Table1 INNER JOIN Table2 ON Table1.ID = Table2.ForeignID

我会的

Hello world, First entry  
Hello world, Second entry  
Bonjour, Third entry  

有没有办法只获得表2中的TOP条目,例如:

Hello world, First entry  
Bonjour, Third entry  

Answer 1

这也有效:

SELECT  Table1.value
        , Table2.value
FROM    Table1 
        INNER JOIN Table2 ON Table1.id = Table2.foreignID
        INNER JOIN (   
          SELECT    MIN(ID) AS ID, ForeignID
          FROM      Table2
          GROUP BY  ForeignID
        ) MinID ON Table2.foreignid = MinID.foreignid
                   AND Table2.id = MinID.id