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我面临的一个问题是有许多查询具有相似的选择语句但不同的连接/位置语句。

下面是我正在通过 CodeIgniter 处理的代码示例。我通常做的是创建一个函数 get()，它接受一组随机键/值。根据传递的键/值，它将生成并运行适当的查询。现在，我想知道这是一种很好的做事方式吗？因为如你所见，这个函数变得越来越复杂。最初，我有一堆函数，例如 get_all()、get_only_lessons() 等，但是不得不用一两行不同的行重复同一组代码变得有点烦人。

我的问题是处理这个问题的最佳方法是什么。

function get($param = NULL)
{
    /*
    SELECT  m.id AS id, CAST(m.order_number AS SIGNED) AS order_number, m.name AS name, m.permalink as permalink, 
        m.suplesson_id as suplesson_id, CAST(sm.order_number AS SIGNED) AS suplesson_order_number
    FROM    lessons m
    JOIN    courses c ON m.course_id = c.id
    LEFT JOIN lessons sm ON m.suplesson_id = sm.id
    WHERE   [various]
    */

    $select =   'm.id AS id, CAST(m.order_number AS SIGNED) AS order_number, m.name AS name, m.permalink as permalink, ';
    $select .= ' m.suplesson_id as suplesson_id';

    if (isset($param['id']) || isset($param['suplesson_order_number']) || isset($param['permalink']))   
        $select .= ', CAST(sm.order_number AS SIGNED) AS suplesson_order_number ';

    $this->db->select($select);
    $this->db->from($this->table_name.' m');
    $this->db->join($this->courses_table_name.' c', 'm.course_id = c.id');

    if (isset($param['id']) || isset($param['suplesson_order_number']) || isset($param['permalink']))
        $this->db->join($this->table_name.' sm', 'm.suplesson_id = sm.id', 'left');

    // where clauses
    if (isset($param['course_id'])) 
        $this->db->where(array('c.id' => $param['course_id']));
    if (isset($param['id'])) 
        $this->db->where(array('m.id' => $param['id']));
    if (isset($param['order_number'])) 
        $this->db->where(array('m.order_number' => $param['order_number']));
    if (isset($param['permalink'])) 
        $this->db->like('m.permalink', $param['permalink'], 'none');
    if (isset($param['suplesson_id'])) 
        $this->db->where(array('m.suplesson_id' => $param['suplesson_id']));
    if (isset($param['suplesson_order_number'])) 
        $this->db->where(array('sm.order_number' => $param['suplesson_order_number']));
    if (isset($param['NULL'])) 
        $this->db->where('m.'.$param['NULL'].' IS NULL');
    if (isset($param['NOT NULL'])) 
        $this->db->where('m.'.$param['NOT NULL'].' IS NOT NULL');

    $this->db->order_by('order_number');

    // filter based on num_rows/offset
    if (isset($param['id']) || isset($param['permalink']))  
        $this->db->limit(1);
    if (isset($param['num_rows']) && isset($param['offset'])) 
        $this->db->limit($param['num_rows'], $param['offset']);

    $query = $this->db->get();

    // return row if expecting 1 result 
    if (isset($param['id']) || isset($param['suplesson_order_number']) || isset($param['permalink']))   
        return ($query->num_rows() == 1) ? $query->row_array() : NULL;

    return ($query->num_rows() > 0) ? $query->result_array() : NULL;
}
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1 回答 1

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运行 DB 查询的常用方法是将模型代码构造为具有多个函数调用，每个函数调用与一个 SQL 语句相关，例如：

function get_user($userId)
{
    $this->db->get_where('user', array('userId' => $userId))
    //...
    //...        
}

function delete_user($userId)
{
    $this->db->delete('user',array('userId' => $userId))
}

您可以创建一个名为 User_model 的模型类，其中包含读取/更新用户表所需的所有功能，因此在您的控制器中您可以调用特定的模型函数

$user = $this->User_model->get_user($userId)

看起来您正在尝试构建一个巨大的模型函数来检查各种参数以确定要运行的 SQL 语句。这不是好的设计，也不适合 Codeignitors MVC 模型。相反，为每个表创建一个单独的模型，然后在每个模型中为您希望运行的每个 SQL 操作创建单独的函数。从您的控制器调用这些模型以获取/更新/删除表中的数据。

于 2012-05-30T20:54:11.907 回答