/**
* 取得有效教室借用.
*
* @return
*/
public function loanClassroom()
{
return $this->hasMany(Loan::class)->join('categories as ct', 'type', '=', 'ct.id')->whereIn('status', Category::getCategoryIds(['loan.status' => ['accepted', 'processing']]))->select('loans.*', 'ct.category', 'ct.name');
}
