发表总计sql codeigniter

Question

当我想通过id使列的总和有一点问题。

表产品

id code name  price quantity 
522 123  Product 1  12  4 

表purchase_items

id product_id quantity 
1  522   5 
2  522   1 

表sale_items

id product_id quantity 
1  522   1 
2  522   1 

功能笨：

$products = $this->alerts->select('products.id as productid, products.code as code, products.name, products.price, sum(sale_items.quantity)') 
     ->from('products'); 
     $this->alerts->join('sale_items', 'products.id = sale_items.product_id');   
     $this->alerts->group_by("products.id"); 

     $products = $this->alerts->select('products.id as productid, products.code as code, products.name, products.price, sum(purchase_items.quantity)') 
     ->from('products'); 
     $this->alerts->join('purchase_items', 'products.id = purchase_items.product_id');   
     $this->alerts->group_by("products.id"); 


     $this->alerts->unset_column('productid'); 

     foreach ($this->result_array() as $product) 
     { 
      $products[] = $product['record']; 
     } 

     return $products; 
    } 

的问题是，对于

purchase_items the result is 12 
sale_items  the result is 4 

结果为什么走的是结果×2？

任何帮助表示赞赏。

Answer 1

因为您正在通过商品主数据（产品表）将采购活动加入到销售活动中。因此，总额中包含的采购行数取决于您有多少行销售额;反之亦然。

您需要将这些查询分开为您在视图中组合的单独SQL语句，也可以使用SQL UNION ALL合并两个语句：一个用于购买，一个用于销售。

两个语句：

$this->alerts 
      ->select('products.id as productid, products.code as code, products.name, products.price, sum(purchase_items.quantity)') 
      ->from('products'); 
      $this->alerts->join('purchase_items', 'products.id = purchase_items.product_id'); 
       $this->alerts->group_by("products.id"); 
      echo "Total Purchases"; 
      echo $this->alerts->generate(); 


$this->alerts 
      ->select('products.id as productid, products.code as code, products.name, products.price, sum(sale_items.quantity)') 
      ->from('products'); 
      $this->alerts->join('sale_items', 'products.id = sale_items.product_id');   
       $this->alerts->group_by("products.id"); 
      echo "Total Sales"; 
      echo $this->alerts->generate(); 

或者，在SQL：

$results = $this->db->query(' 
    SELECT products.id as productid, products.code as code, products.name, products.price, ''Purchase'' as transaction, sum(purchase_items.quantity) 
    FROM products 
    JOIN purchase_items ON products.id = purchase_items.product_id 
    GROUP BY products.id 
    UNION ALL 
    SELECT products.id as productid, products.code as code, products.name, products.price, ''Sale'' as transaction sum(sales_items.quantity) 
    FROM products 
    JOIN sales_items ON products.id = sales_items.product_id 
    GROUP BY products.id')->result_array(); 

// Echo $results.... 

编辑： 我不完全知道你在你的Alerts模式，但在你修改查询您正在向变量$products分配两次SQL语句但不执行语句？

此外，请确保您的警报模型延伸CI_Model。

更笨的标准语法，我会做这样的事情：

// In Controller, assuming the Alerts model is loaded, and using method chaining. 

    // Get all sales. By the way, you normally have to group on all columns *not* being aggregated. You might 
    // get unexpected results by grouping on price, unless the price never changes. 
    $this->alerts->select('products.id as productid, products.code, products.name, products.price, sum(sale_items.quantity) as quantity') 
      ->from('products') 
      ->join('sale_items', 'products.id = sale_items.product_id') 
      ->group_by('products.id, products.code, products.name, products.price'); 
    $sales = $this->alerts->get()->result_array(); 

    // Get all purchases 
    $this->alerts->select('products.id as productid, products.code, products.name, products.price, sum(purchase_items.quantity) as quantity') 
      ->from('products') 
      ->join('purchase_items', 'products.id = purchase_items.product_id') 
      ->group_by(products.id, products.code, products.name, products.price); 
    $purchases = $this->alerts->get()->result_array(); 

    // Put it all together 
    $products = array_merge($sales, $purchases); 

    // And now do something with your combined results $products. Send to view, echo etc.