我有以下2个示例表:
Orders:
+--------+----------+
| UserID | ProductID|
+--------+----------+
| 1 | 1 |
| 2 | 4 |
| 3 | 3 |
| 4 | 3 |
+--------+----------+
Products:
+----------+-------+
| ProductID| Price |
+----------+-------+
| 1 | A |
| 2 | D |
| 3 | G |
| 4 | J |
+----------+-------+
我想返回ProductID
表中仅具有值(或具有Products
)的UserID
表的Orders
。
结果将是下面的列:
+----------+
| ProductID|
+----------+
| 1 |
| 3 |
| 4 |
+----------+
答案 0 :(得分:2)
SELECT ProductID FROM Products WHERE ProductID IN (SELECT ProductID from Orders)
答案 1 :(得分:0)
该怎么做:
select distinct productId
from orders;
大概productid
在表中是正确的-因此您不必检查是否确实发生匹配。