在laravel 5中的AND声明雄辩

how can I make this, like get from "table" where "student_staff" is equal to "student" 'AND' where "department" is equal to "all" or "department" is equal to "department1? any help, ideas, clues, recommendations, suggestions?

so far, what I have tried

$notifications = notification::where('student_staff', '=', 'student')
    ->where('department', '=', 'all')
    ->orWhere('department', '=', 'department1')->get();

To answer the question in your comment, there is nothing to extend. The default is already 'and'. For example, lets take a look at what you wrote:

select from "table" where "name" is equal to "jason" AND where "age" is equal to "16"

The default where clause already does what you want.

Model::where('name', '=', 'jason')
     ->where('age', '=', 16)
     ->get();

This turns into something along the lines of select * from `TABLE` where `name` = jason and `age` = 16.

If you take a look at the where method in either the eloquent/query builder, you will see this:

public function where($column, $operator = null, $value = null, $boolean = 'and')

As you can see from the 4th parameter, the default is already 'and'. On a related note, you can override that and put 'or', if you want.

Model::where('name', '=', 'jason')
     ->where('age', '=', 16, 'or')
     ->get();

There is also a orWhere method that does that for you though.

Model::where('name', '=', 'jason')
     ->orWhere('age', '=', 16)
     ->get();

This will turn into something like this:

select * from `TABLE` where `name` = jason or `age` = 16.

Edit: Just noticed that you edited your question.

"table" where "student_staff" is equal to "student" 'AND' where "department" is equal to "all" or "department" is equal to "department1

I think what you want is actually this: "student_staff" is equal to "student" 'AND' (where "department" is equal to "all" or "department" is equal to "department1)

This is called parameter grouping. Docs on that here: http://laravel.com/docs/5.1/queries#advanced-where-clauses

To achieve this statement, it would be something like this:

$models = Model::where('student_staff', '=', 'student')
                ->where(function($query) {
                    $query->where('department', '=', 'all')
                          ->orWhere('department', '=', 'department1');
                })->get();