Question

我的查询通过visual basic访问数据库时出现问题。可以说我有两张桌子。

+-------+-------------+-------------+------------+
| ID    | Date1       | Date2       | CustomerID |
+-------+-------------+-------------+------------+
|     1 | 1-1-2013    | 1-1-2012    |          1 |
|     2 | 1-1-2013    | 1-1-2012    |          1 |
|     3 | 1-1-2013    | 1-1-2012    |          2 |
|     4 | 1-1-2013    | 1-1-2012    |          3 |
|     5 | 1-1-2013    | 1-1-2012    |          3 |
+-------+-------------+-------------+------------+

和

+----------+---------+
| ID       |  Name   |
+----------+---------+
|        1 | John    |
|        2 | Tina    |
|        3 | Patrick |
+----------+---------+

我想在第一个表格中仅使用Customer - ID中的唯一数字得到结果，如下所示。

+----------+----------+-------------+------------+
| ID       |   Date1  |    Date2    | CustomerID |
+----------+----------+-------------+------------+
|        1 | 1-1-2013 | 1-1-2012    |          1 |
|        3 | 1-1-2013 | 1-1-2012    |          2 |
|        4 | 1-1-2013 | 1-1-2012    |          3 |
+----------+----------+-------------+------------+

我尝试过这个查询，但没有运气。

sqL = " SELECT DISTINCT Order.ID, Order.Date1, Order.Date2, Customer.Name 
FROM Order (Order INNER JOIN Customer ON Order.CustomerID = Customer.ID)"

但代码并没有给我我想要的结果。能否请我帮我查询一下。

Answer 1

更新这样做

SELECT q.OrderID, o.Date1, o.Date2, o.CustomerID, c.Name AS CustomerName
  FROM 
(
  (SELECT CustomerID, MIN(ID) AS OrderID 
     FROM [Order] 
    GROUP BY CustomerID
  )  AS q INNER JOIN [Order] AS o
  ON q.OrderID = o.ID
) INNER JOIN Customer AS c
ON o.CustomerID = c.ID

输出：

OrderID | Date1    | Date2    | CustomerID | CustomerName
--------|----------|----------|------------|-------------
1       | 1/1/2013 | 1/1/2012 | 1          | John
3       | 1/1/2013 | 1/1/2013 | 2          | Tina
4       | 1/1/2013 | 1/1/2012 | 3          | Patrick

更新：根据您的评论，您的真实查询可能会显示为

SELECT q.ID, o.ID_narocila, o.datum_sprejema, o.rok_izdobave, o.status_artikla, o.status_narocila o.ID_stranke, c.naziv
  FROM 
(
  (SELECT ID_stranke, MIN(ID) AS ID
     FROM Narocilo 
    GROUP BY ID_stranke
  )  AS q INNER JOIN Narocilo AS o
  ON q.ID = o.ID
) INNER JOIN Stranke AS c
ON o.ID_stranke = c.ID

Answer 2

从您显示的所需结果集中，以下查询将起作用：

SELECT Min(T2.ID) AS MinOfID, Min(T1.Date1) AS MinOfDate1, Min(T1.Date2) AS MinOfDate2, T1.CustomerID
FROM T2 INNER JOIN T1 ON T2.ID = T1.CustomerID    
GROUP BY T1.CustomerID;

区分一列有多个结果

2 个答案: