php - 嵌套mysql while循环未返回预期结果

Question

我有 2 个表，我正在尝试使用嵌套的 while 循环来列出所有可能性。不幸的是，我只得到了一小部分结果。任何帮助深表感谢。

产品表

Product_ID | Product_Name | Product_Desc
0          | Box          | Big Box     
1          | Toy          | Nice Toy  

城市表

City_ID    | City_Name 
0          | Cincinnati    
1          | Detroit
2          | San Francisco
3          | San Diego
4          | New York

预期结果:

0 Box Big Box 0 Cincinnati
0 Box Big Box 1 Detroit
0 Box Big Box 2 San Francisco
0 Box Big Box 3 San Deigo
0 Box Big Box 4 New York
1 Toy Nice Toy 0 Cincinnati
1 Toy Nice Toy 1 Detroit
1 Toy Nice Toy 2 San Francisco
1 Toy Nice Toy 3 San Diego
1 Toy Nice Toy 4 New York

我的错误结果:

0 Box Big Box 0 Cincinnati
1 Toy Nice Toy 0 Cincinnati

这是我的代码:

query = "SELECT * FROM Products";
$result = mysqli_query($con, $query);

$query2 = "SELECT * FROM Cities";
$result2 = mysqli_query($con, $query2);


while($row = mysqli_fetch_assoc($result))
    {
         $product_id = $row['Product_ID'];
         $product_name = $row['Product_Name'];
         $product_desc = $row['Product_Desc'];

        while($row = mysqli_fetch_assoc($result2))
        {
        $city_id = $row['City_ID'];
        $city_name = $row['City_Name'];
        }

    echo "$product_id $product_name $product_desc $city_id $city_name\n";

}

不幸的是，上面的方法不起作用，我只得到这个结果。我应该使用 foreach 产品吗？

Answer 1

实际上，您可以在不使用嵌套循环的情况下通过单个查询获得相同的结果

$query = "SELECT p.*,c.* FROM Products p,City c";