Question

我有一个名为“products”的数据库，其中有一列“categories”。此表包含四类产品，即electronic，Decoration，clothes和vehicle。我的目标是显示这些category与count我e:if there are four products belongs to category electronic, then output should be like this :electronic=4等等

我的代码

    public function category()
      {
      $arrayCategorys = ['electronic','Decoration','clothes','vehicle'];
      $data = [];
      foreach($arrayCategorys as $arrayCategory)
       {
      $sql = "SELECT  count(id) FROM products WHERE   categories='$arrayCategory'";
      $records = \DB::select($sql); 
      $data = array_merge_recursive($data, [

                  "{$arrayCategory}" =>isset($records[0]->count),

            ]);
      $data=array_filter($data);
      dd($data);
      }
 }

我想要这样的节目输出

'electronic'=>'4',

'Decoration'=>'2',

'clothes'=>'2',

根据数据库中的数据，

'vehicle'=>'1' 但我什么都没得到，[]

Answer 1

GROUP BY

时，您可以COUNT这样的方式

SELECT categories,COUNT(*)  
FROM products 
GROUP BY categories;

$result = DB::table('products')
            ->select('products.categories', 
                      DB::raw('count(products.id) as category_count')
                    )
            ->orderBy('products.id', 'asc')
            ->groupBy('products.categories')
            ->get();

想法： http://www.w3resource.com/mysql/aggregate-functions-and-grouping/aggregate-functions-and-grouping-count-with-group-by.php

编辑：虽然我不熟悉laravel5语法，但这可能适合你

OnGlobalLayoutListener

Answer 2

您使用了isset($records[0]->count)，但计数的列名称为count(id)。将计数命名为count，如此"SELECT count(id) AS count FROM products WHERE categories='$arrayCategory'"。并且你只能通过检查是否设置来获得计数。删除isset，然后使用$records[0]->count。代码应如下所示：

 public function category()
 {
      $arrayCategorys = ['electronic','Decoration','clothes','vehicle'];
      $data = [];
      foreach($arrayCategorys as $arrayCategory)
       {
      $sql = "SELECT  count(id) AS count FROM products WHERE   categories='$arrayCategory'";
      $records = \DB::select($sql); 
      $data = array_merge_recursive($data, [

                  "{$arrayCategory}" =>$records[0]->count,

            ]);
      $data=array_filter($data);
      dd($data);
      }
 }

获取null数组PHP

2 个答案: