CI3捕获SQL语句异常

之前遇到数据库语句错误，一直无法捕获异常

public function hehe()
    {
        try {
            $data = array(
                'title' => 123134,
                'content' => 'aaaaa',
                'aaa' => 222
            );
            $res = $this->db->insert('news', $data);
        } catch (\Throwable $th) {
            p(123232323);
        }
    }

 后来发现，在model里面执行的SQL语句可以正常捕获到

//只能在model里面执行的数据库语句，才能被捕获

public function hehe()
    {
        try {            //捕获SQL语句错误
            $data = array(
                'title' => 123134,
                'content' => 'aaaaa',
                'aaa' => 222        //非数据库字段
            );
            $md = $this->model('News_model');
            $res = $md->add();
        } catch (\Throwable $th) {

              p('数据库语句错误');

        }
    }