php - PHP 获取空数组

Question

我有一个名为“products”的数据库，其中有一列“categories”。该表包含四类产品，即电子、装饰品、衣服和车辆。我的目标是显示这些category及其count ie:如果有四种产品属于电子类别，则输出应如下所示: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);
      }
 }

我想要这样显示输出

'electronic'=>'4',

'Decoration'=>'2',

'clothes'=>'2',

'vehicle'=>'1' 根据数据库中的数据但我什么也没得到，[]

Answer 1

当您COUNT时，您可以像这样GROUP BY您的类别

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

创意: 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，但这可能对你有用

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