Codeigniter查询返回false

Question

我有一个查询来获取员工的日程安排并将其显示在表格中。我使用默认计划对一些员工进行了抽样，但是当我尝试检索具有不同计划的其他员工时，它总是返回false，表示该表为空。这是我的查询：

function get_Sked($id,$from,$to)
{
    $query = "SELECT c.dt, a.TimeFrom,a.TimeTo FROM schedule a LEFT JOIN cal c ON a.SkedDate = c.dt AND a.EmpID = ? WHERE c.dt BETWEEN DATE(?) AND DATE(?) GROUP BY c.dt ORDER BY c.dt ASC";

    $query = $this->db->query($query,array($id,$from,$to));

    if($query->num_rows() == 0)
    {
        return false;
    }
    else
    {
        return $query->result_array();
    }
}

这是调用它的方法：

$data['sked'] = $this->DBmodel->get_Sked($id,$dFrom,$dTo);

    if($data['sked'] == false)
    {
        echo "Default Schedule of 8:00 am to 5:00 pm."; //if table is empty show default sched.

        var_dump($data['sked']);
    }
    else
    {
        foreach($data['sked'] as $val) //this will show the content of the table.

我使用与其他查询序列相同的查询序列，并且只有这个问题没有问题.....

我将查询结构更改为：

$this->db->select('c.dt,a.TimeFrom,a.TimeTo');
    $this->db->from('cal c');
    $this->db->join('schedule a','a.SkedDate = c.dt');
    $this->db->where('a.EmpID',$id);
    $this->db->where('c.dt',$from);
    $this->db->where('c.dt',$to);
    $query = $this->db->get();

但仍然返回false ....