我有一個FamilyMember模型和一個SubscriptionCharge模型，SubscriptionCharge存儲每個家庭成員數月的費用。我必須選擇收費總額大于特定金額的會員。$members=FamilyMember::whereHas('subscription_charge', function ($qq) {   $qq->where(); // how to check sum of column 'amount' in where})->get();如何在where條件中檢查“金額”列的總和