如何在laravel中使用增量函数

Question

我正在使用DB将值存储在数据库中。

我有“课程费用”列，第i列中的“ course_fees”值要“增加”。

例如

 DB::table('student')->where('registration_id','=', $request->registration_id)->increment(['course_fees' =>$request->course_fees]);

此代码增加插入值

我如何在下面的代码中修改上面的“ course_fees”值的增量

      DB::table('student')->where('registration_id','=', $request->registration_id)->update(['payment_date' => $request->payment_date,'balance_fees' => $request->balance_fees,'course_fees' =>$request->course_fees]);

Answer 1

您不能使用此方法来增加多个字段。您可以使用：

$studentQuery = DB::table('student')->where('registration_id','=', $request->registration_id);

(clone $studentQuery)->increment('payment_date',$request->payment_date);
(clone $studentQuery)->increment('balance_fees', $request->balance_fees);
(clone $studentQuery)->increment('course_fees', $request->course_fees);

但是通过这种方式，您将运行3个数据库查询以进行更新。

但是，如果您确定为registration_id找到了完全相同的记录，则可以这样操作：

$student = DB::table('student')->where('registration_id','=', $request->registration_id)->first();

$student->update([
   'payment_date' => $student->payment_date + $request->payment_date,
   'balance_fees' => $student->balance_fees + $request->balance_fees,
   'course_fees' => $student->course_fees + $request->course_fees
]);

编辑

如果只想增加course_fees列，并想从输入中更新其他2列，则可以使用：

DB::table('student')->where('registration_id','=', $request->registration_id)
->increment('course_fees' , $request->course_fees, [
   'payment_date' => $request->payment_date,
   'balance_fees' => $request->balance_fees
])

这是documentation about increment/decrement方法。

Answer 2

尝试一下如果只想更新balance_fees和payment_date

$data = DB::table('student')->where('registration_id','=', $request->registration_id)->first();
$data->update(['payment_date' => $data->payment_date + $request->payment_date,
   'balance_fees' => $data->balance_fees + $request->balance_fees]);

OR如果您只想更新cource value

$data = DB::table('student')->where('registration_id','=', $request->registration_id)->first();
$data->update(['course_fees' => $student->course_fees + $request->course_fees]);