how to use increment() and decrement() in laravel

Question

I have a table total_count

+----+--------+-------+------+---------+---------+---------+
| id | studid | month | year | acls_id | total_p | total_a |
+----+--------+-------+------+---------+---------+---------+
| 1  |   30   |  08   | 2015 |   12    |    5    |    2    |
| 2  |   35   |  08   | 2015 |   12    |    5    |    2    |
| 3  |   52   |  08   | 2015 |   12    |    5    |    2    |
| 4  |   53   |  08   | 2015 |   12    |    5    |    2    |
| 5  |   54   |  08   | 2015 |   12    |    5    |    2    |
| 6  |   55   |  08   | 2015 |   12    |    5    |    2    |
| 7  |   30   |  09   | 2015 |   12    |    3    |    0    |
| 8  |   35   |  09   | 2015 |   12    |    3    |    0    |
| 9  |   52   |  09   | 2015 |   12    |    2    |    1    |
| 10 |   53   |  09   | 2015 |   12    |    3    |    0    |
| 11 |   54   |  09   | 2015 |   12    |    3    |    0    |
| 12 |   55   |  09   | 2015 |   12    |    3    |    0    |
+----+--------+-------+------+---------+---------+---------+

I want to increment and decrement for each student total_p and total_a.

when i am edit my student attendance list.

eg: studid 30 total_p = 5 and total_a= 2 ,so iam edit my attendance present become absent .

so want decrement total_p by 1 and increment total_a by 1.

So I'd like to get the total of each month for each studid and a increment and decrement of total_p and total_a for the total months.

My controller code is

foreach ($student as $student) {
            if ($present == 0) {
                $query = DB::table($wys_total_attend_table)
                    ->where('studid', $student->id)
                    ->where('smonth', '=', $date_exploded[1])
                    ->where('syear', '=', $date_exploded[2])
                    ->update([
                        'stotal_p' => DB::raw('stotal_p - 1'),
                        'stotal_a' => DB::raw('stotal_a + 1'),
                    ]);
            } elseif ($present == 1) {
                $query = DB::table($wys_total_attend_table)
                    ->where('studid', $student->id)
                    ->where('smonth', '=', $date_exploded[1])
                    ->where('syear', '=', $date_exploded[2])
                    ->update([
                        'stotal_p' => DB::raw('stotal_p + 1'),
                        'stotal_a' => DB::raw('stotal_a - 1'),
                    ]);
            }
        }

but it doesn't work..

How to use increment() and decrement() in query builder format?

for eg: if i only edit studid = 30 attendance increment total_p value 1 and (present == 1) studid = 30 total_p = 6 and total_a = 1 and other studid values are old value.

Answer 1

increment() and decrement() do not return a Query Builder object, so you cannot chain your calls like you do in your code:

->increment('stotal_p', 1)->decrement('stotal_a', 1); 

You'll need to call each method separately. Moreover, 1 is the default value for the increment/decrement, so no need to pass it.

This should do the trick:

$query = DB::table($wys_total_attend_table)
  ->where('studid',$student->id)                                     
  ->where('smonth','=',$date_exploded[1])
  ->where('syear','=',$date_exploded[2]);

$query->increment('stotal_a');
$query->decrement('stotal_p');

Answer 2

From Laravel 5.7+ you can increment or decrement the given column by using increment() or decrement() methods without writing the manual update statement.

Laravel Doc & Example

https://laravel.com/docs/5.8/queries#increment-and-decrement

DB::table('users')->increment('votes');
DB::table('users')->increment('votes', 5);

DB::table('users')->decrement('votes');
DB::table('users')->decrement('votes', 5);

Get the Student Attendance

$studentAtd = DB::table($wys_total_attend_table)
  ->where('studid',$student->id)                                     
  ->where('smonth','=',$date_exploded[1])
  ->where('syear','=',$date_exploded[2]);

Increment or Decrement Attendance column

$studentAtd->increment('stotal_a');
$studentAtd-> decrement('stotal_p');