Laravel 对某一列进行筛选然后求和sum()的例子

StudentLessonProgress::where('student_info_id', $student_info_id)
   - sum('total_left_class_num');

array:1 [▼ 
0 =  array:3 [▼ 
“query” =  “select sum(total_left_class_num) as aggregate from student_lesson_progress where student_info_id = ?” 
“bindings” =  array:1 [▶] 
“time” =  51.48 
] 
]

Product::where('status',1)- first(
 array(
  \DB::raw('SUM(profit) as profit'),
  \DB::raw('SUM(order_count) as order_count')
 )
)- toArray();