php - MYSQL Query-Building Form With Queries-多表汇总

Question

我想创建一个报告来回显类别，然后是每个类别的总销售额。

数据库分为 4 个表:

1)类别表(保存类别名称和id)
2)产品(通过类别id从这里选择产品)
3) 销售(持有与销售项目相关的销售 ID)
4) 促销品(包含所有促销品 和销售量)

我需要通过category id获取我认为的产品，然后通过date获取销售额，然后从sale items中选择按 sale id(仅按日期)和按 product id(因此它们仅按相应类别)。

这是我的尝试..但没有成功，我不确定我是否走在正确的道路上，我们将不胜感激 :) 谢谢!

//Select The Category Table
$query="SELECT * FROM categories";
$result=mysql_query($query);
$num=mysql_numrows($result); 

while($row = mysql_fetch_assoc($result))
{
   echo $row['name']." ";

   //store category id in a string
   $cID = $row['id']."";

   //get the product id's
   $productquery = "SELECT id FROM products WHERE category_id = $cID";
   $productresult = mysql_query($productquery);
   $numproducts = mysql_num_rows($productresult);
   $productrow = mysql_fetch_assoc($productresult);
   $productid = $productrow['id']."";
 //  echo $productid;


   //get sale id from table to use to get sale items
   $salesquery = "SELECT * FROM sales WHERE date BETWEEN '2015-01-01 00:00:00' AND '2015-06-01 00:00:00'";
   $salesresult = mysql_query($salesquery);
   $salesnumber = mysql_num_rows($salesresult);
   $salesrow = mysql_fetch_assoc($salesresult);
   $salesid = $salesrow['id']."";
  // echo $salesid;

  //put it all together and try to sum up the subtotal col where only the category product will be tallied
  $saleitemsquery = "SELECT SUM(subtotal) FROM sales_items WHERE sale_id = $salesid AND product_id = $productid";
  $totalresult = mysql_query($saleitemsquery);
 // $totalrow = mysql_fetch_assoc($totalresult);
 echo $totalresult;

   ?>
   <br /> <br />

   <?php
}
?>

Answer 1

我敢肯定这不是 100% 准确，但希望它足以让您走上正确的轨道。

select c.name as Name, sum(i.subtotal) as Total
from sale_items i
       inner join sales s on s.id = i.sale_id
       inner join products p on p.id = i.product_id
       inner join categories c on c.id = p.category_id
where s.date BETWEEN '2015-01-01 00:00:00' AND '2015-06-01 00:00:00'
group by c.id