通過使用PHP和MySQL聯接多個表來查詢以獲取多個數據

Question

我需要一個幫助。使用PHP和Mysql加入多表后，我需要獲取一些數據，因此我需要對此進行適當的查詢。我在下面解釋我的表結構。

db_order：

id     order_id    promocode

1      10           A12016

2       11          A12016

db_order_product：

id   order_id   pro_data_id  quantity

1     10         20          2

2     10         22          3

3     11         20          1

db_product_info：

pro_data_id   product_name

20            abc

22            xyz

我已經嘗試過類似下面的方法，但是它不起作用。

$sqlqry="select * from db_order order by id desc";
$orderqry=mysqli_query($con,$sqlqry);
while($row=mysqli_fetch_assoc($orderqry)){
    $order_id=$row['order_id'];
    $sqlproqry="select * from db_order_products where order_id='".$order_id."'";
    $proqry=mysqli_query($con,$sqlproqry);
    while($row1=mysqli_fetch_assoc($proqry)){
        $product_data_id=$row1['pro_data_id'];
        $sqldataqry="select * from db_product_data where pro_data_id='".$product_data_id."'";
        $prodataqry=mysqli_query($con,$sqldataqry);
        while($prodatarow=mysqli_fetch_assoc($prodataqry)){
            $pro_id=$prodatarow['pro_Id'];
            $sqlpro="select * from db_product_info where pro_Id='".$pro_id."'";
            $prodata=mysqli_query($con,$sqlpro);
            $prorow=mysqli_fetch_array($prodata);
        }
    }
$result[]=array('id'=>$row['id'],'order_id'=>$row['order_id'],'promocode'=>$row['promocode'],'order_pro_id'=>$row1['id'],'pro_data_id'=>$row1['pro_data_id'],'pro_quantity'=>$row1['quantity'],'product_name'=>$prorow['Product_name']);
}
echo json_encode($result);

在這里我需要第一個用戶進入db_order表以獲取所有值，並根據order_id從db_order_product獲取所有數據，然后根據db_order_product表中的pro_data_id從db_order_product中獲取數據，並db_product_info返回db_product_info中的所有數據。請幫助我。

Answer 1

只需使用一個簡單的JOIN

SELECT o.id, o.order_id, o.promocode, p.id AS order_pro_id, p.prod_data_id, p.quantity AS pro_quantity, i.product_name
FROM db_order AS o
JOIN db_order_products AS p ON o.order_id = p.order_id
JOIN db_product_data AS d ON p.pro_data_id = d.pro_data_id
JOIN db_product_info AS i ON i.pro_Id = d.pro_Id
ORDER BY o.id DESC

Answer 2

您必須解決您的查詢：

使用以下查詢：

  select * from db_order,db_order_product,db_product_info where db_order.order_id=db_order_product.order_id and db_order_product.pro_data_id=db_product_info.pro_data_id

Answer 3

SELECT dor.id,dordor.order_id,dor.promocode
FROM db_order AS dor
JOIN db_order_product AS dop ON dop.order_id = dor.order_id
JOIN db_product_info as dpi ON dpi.pro_data_id=dop.pro_data_id