Records where value is not equal to current value - laravel

Question

I have 7 Departments and an Employee that is assigned to 2 of them through a polymorphic join model called DepartmentItem. When I run the following I expect to get 5 records that the employee does not belong to, but instead I get all 7.
$employee = \App\Employee::find(1);
$departments = \App\Department::join('department_items', 'department_items.department_id', '=', 'departments.id')
->select('departments.*')
->groupBy('departments.id')
->where('company_id', $employee->company_id)
->where('department_items.item_id', '!=', $employee->id)
->where('department_items.item_type', 'employee')
->get();
dd($departments);
This returns 7 departments when it should only return 5. When I change '!=' to '=' it returns the 2 departments that the employee is assigned to.
Here are the model relations:
// Company
public function departments() {
return $this->hasMany(Department::class);
}
public function employees() {
return $this->hasMany(Employee::class);
}
// Department
public function company() {
return $this->belongsTo(Company::class);
}
public function employees() {
return $this->morphedByMany(Employee::class, 'item', 'department_items');
}
// DepartmentItem
public function department() {
return $this->belongsTo(Department::class);
}
public function item() {
return $this->morphTo();
}
// Employee
public function company() {
return $this->belongsTo(Company::class);
}

Answer 1

You should use <> instead of != as where clause method takes mysql operators.
So your code should be like this:
$departments = \App\Department::join('department_items', 'department_items.department_id', '=', 'departments.id')
->select('departments.*')
->groupBy('departments.id')
->where('company_id', $employee->company_id)
->where('department_items.item_id', '<>', $employee->id)
->where('department_items.item_type', 'employee')
->get();
Hope this helps!