Php 可恢复的致命错误：类DateTime的对象

我正在尝试选择我的数据库，我设置的日期如下

$endDate = new DateTime($fetch['loan_end']);
$endDate->add(new DateInterval('P5D'));

在此执行：

$stmtBal = $controller->runQuery("SELECT SUM(amount) 
                                      FROM tbl_paid
                                      WHERE pay_date <= :endDate 
                                      AND (c_id=:c_id AND (transaction_num=:transaction_num))");
    $stmtBal->execute(array(":endDate"         =>  $endDate, 
                            ":c_id"            =>  $get_id,
                            ":transaction_num" =>  $fetch['transaction_num']));

$stmtBal=$controller->runQuery（“选择总和（金额））
从tbl_支付
在哪里付款日期试试这个


$stmtBal->execute（数组（“：endDate”=>$fetch['loan\u end']，“：c\u id”=>$get\u id，”：transaction\u num”=>$fetch['transaction\u num']）；