分页原理是什么

数据分页需要以下几个条件：

1. 参与分页的总条数 【$msg_count】 ，该值通过数据库查询可以获取到;

2. 每页显示的条数【$pagesize】 ，这个数值由自己定义;

3. 当前页的页码数 【$page】，该数值通过地址栏传递和接收；

4. 可以通过以上资料计算出总页数 【$pagecount】 ，此处需要借助ceil();

【$pagecount = ceil($msg_count/$pagesize);】

5. 数据库查询借助sql语句中的【limit】来实现数据的变化：

例如：

select * from 表名 where 条件 limit $startnum , $pagesize;

而$startnum = ($page-1)*$pagesize;

实例：

/**
 * 取得上次的过滤条件
 * @param   string  $param_str  参数字符串，由list函数的参数组成
 * @return  如果有，返回array('filter' => $filter, 'sql' => $sql)；否则返回false
 */
function get_filter($param_str = '')
{
    $filterfile = basename(PHP_SELF, '.php');//string basename ( string $path [, string $suffix ] )　　　　　　　　　　　　　　　　　　　　　　　　　　　　　返回路径中的文件名部分如果文件名是以 suffix 结束的，那这一部分也会被去掉。 
    if ($param_str)
    {
        $filterfile .= $param_str;
    }
    if (isset($_GET['uselastfilter']) && isset($_COOKIE['ECSCP']['lastfilterfile'])
        && $_COOKIE['ECSCP']['lastfilterfile'] == sprintf('%X', crc32($filterfile)))
    {
        return array(
            'filter' => unserialize(urldecode($_COOKIE['ECSCP']['lastfilter'])),
            'sql'    => base64_decode($_COOKIE['ECSCP']['lastfiltersql'])
        );
    }
    else
    {
        return false;
    }
}

/**
 * 保存过滤条件
 * @param   array   $filter     过滤条件
 * @param   string  $sql        查询语句
 * @param   string  $param_str  参数字符串，由list函数的参数组成
 */
function set_filter($filter, $sql, $param_str = '')
{
    $filterfile = basename(PHP_SELF, '.php');
    if ($param_str)
    {
        $filterfile .= $param_str;
    }
    setcookie('ECSCP[lastfilterfile]', sprintf('%X', crc32($filterfile)), time() + 600);
    setcookie('ECSCP[lastfilter]',     urlencode(serialize($filter)), time() + 600);
    setcookie('ECSCP[lastfiltersql]',  base64_encode($sql), time() + 600);
}

/**
 * 供货商资源管理
 * @param    bool    $is_pagtion
 * @return    array   $arr
 */
function suppliers_resource_manage($is_pagtion=true)
{
    global $db,$ecs;
    $result = get_filter();
    if ($result === false)
    {
        $aiax = isset($_GET['is_ajax']) ? $_GET['is_ajax'] : 0;
        /* 过滤信息 */
        $filter['sort_by'] = empty($_REQUEST['sort_by']) ? 'r.resource_id' : trim($_REQUEST['sort_by']);
        $filter['sort_order'] = empty($_REQUEST['sort_order']) ? 'DESC' : trim($_REQUEST['sort_order']);
        $filter['resource_id'] = empty($_REQUEST['resource_id'])  ? '' : $_REQUEST['resource_id'];
        $filter['admin_name'] = empty($_REQUEST['admin_name'])  ? '' : trim($_REQUEST['admin_name']);
        $filter['resource_name'] = empty($_REQUEST['resource_name'])  ? '' : trim($_REQUEST['resource_name']);
        $filter['admin_id']  = isset($_REQUEST['admin_id'])?intval($_REQUEST['admin_id']):'-1';
        $filter['resource_type'] = empty($_REQUEST['resource_type']) ? '-1' : intval($_REQUEST['resource_type']);
        $filter['resource_status'] = empty($_REQUEST['resource_status']) ? '-1' : intval($_REQUEST['resource_status']);
        $filter['resource_rank'] = empty($_REQUEST['resource_rank']) ? '-1' : intval($_REQUEST['resource_rank']);
        $filter['resource_key'] = empty($_REQUEST['resource_key'])  ? '' : trim($_REQUEST['resource_key']);
        $filter['menuid'] = 7; 
        $where = 'WHERE 1 ';
        /* 分页大小 */
        $filter['page'] = empty($_REQUEST['page']) || (intval($_REQUEST['page']) <= 0) ? 1 : intval($_REQUEST['page']);

        if (isset($_REQUEST['page_size']) && intval($_REQUEST['page_size']) > 0)
        {
            $filter['page_size'] = intval($_REQUEST['page_size']);
        }
        elseif (isset($_COOKIE['ECSCP']['page_size']) && intval($_COOKIE['ECSCP']['page_size']) > 0)
        {
            $filter['page_size'] = intval($_COOKIE['ECSCP']['page_size']);
        }
        else

        {
            $filter['page_size'] = 15;
        }
        
        if(!empty($filter['resource_id']))
        {
            $resource_id = $filter['resource_id'] == -1 ? 0 : $filter['resource_id'];
            $where .= " and r.resource_id='".$resource_id."'";
        }
        if($filter['resource_name']){
            $where .= " AND r.resource_name like '%".mysql_like_quote($filter['resource_name'])."%' ";
        }
        if($filter['admin_id'] > -1)
        {
            $where .= " AND r.admin_id = '".$filter['admin_id']."' ";
        }
        if ($filter['resource_type'] > -1) 
        {
            $where .= " AND r.resource_type = '" . $filter['resource_type'] . "'";
        }
        if ($filter['resource_status'] > -1) 
        {
            $where .= " AND r.resource_status = '" . $filter['resource_status'] . "'";
        }
        if ($filter['resource_rank'] > -1) 
        {
            $where .= " AND r.resource_rank = '" . $filter['resource_rank'] . "'";
        }
        if($filter['resource_key']){
            $where .= " AND r.remark like '%".mysql_like_quote($filter['resource_key'])."%' ";
        }
        /* 记录总数 */
        $sql = "SELECT COUNT(r.resource_id) FROM " . $ecs->table('suppliers_resource')." as r 
                    LEFT JOIN ".$ecs->table('admin_user') . " as u
                        ON u.user_id = r.admin_id  " . $where;
        $filter['record_count']   = $db->getOne($sql);
        $filter['page_count']     = $filter['record_count'] > 0 ? ceil($filter['record_count'] / $filter['page_size']) : 1;
        /* 查询 */
        $sql = "SELECT r.resource_id, u.user_name as admin_name, r.resource_name, r.resource_link, r.resource_type, r.resource_status, r.resource_rank, r.remark, r.add_time FROM " . $ecs->table('suppliers_resource') . " as r 
                    LEFT JOIN " . $ecs->table('admin_user') . " as u ON u.user_id = r.admin_id  " . $where;

        $sort_by  = $filter['sort_by'];
        $sort_order = $filter['sort_order'];
        $sql .="GROUP BY r.resource_id ORDER BY " . $sort_by . " " . $sort_order;
        if($is_pagtion)
        {
            $sql .=" LIMIT ".($filter['page'] - 1)*$filter['page_size'].",".$filter['page_size'];
        }
        set_filter($filter, $sql);
    }
    else
    {
        $sql    = $result['sql'];
        $filter = $result['filter'];
    }
    $query=$sql;

    $row = $db->getAll($sql);
    /* 格式话数据 */
    foreach ($row AS $key => $value)
    {   
        if ($row[$key]['resource_type'] == 1) {
            $row[$key]['resource_type'] = '中模';
        }elseif ($row[$key]['resource_type'] == 2) {
            $row[$key]['resource_type'] = '泳装';
        }elseif ($row[$key]['resource_type'] == 3) {
            $row[$key]['resource_type'] = '阿里';
        }elseif ($row[$key]['resource_type'] == 2) {
            $row[$key]['resource_type'] = '17网';
        }
        if ($row[$key]['resource_status'] == 1) {
            $row[$key]['resource_status'] = '已审核';
        }elseif ($row[$key]['resource_status'] == 2) {
            $row[$key]['resource_status'] = '已弃用';
        }
        if ($row[$key]['resource_rank'] == 1) 
        {
            $row[$key]['resource_rank'] = 'A';
        }elseif ($row[$key]['resource_rank'] == 2) {
            $row[$key]['resource_rank'] = 'B';
        }elseif ($row[$key]['resource_rank'] == 3) {
            $row[$key]['resource_rank'] = 'C';
        }
        if(strpos($row[$key]['resource_link'], 'http://') === false)
        {
            if (strpos($row[$key]['resource_link'], 'https://') === false) 
            {
                $row[$key]['resource_link'] = substr_replace($row[$key]['resource_link'], 'http://', 0, 0);
            }
        }
    }
    $arr = array('result' => $row, 'filter' => $filter, 'page_count' => $filter['page_count'], 'record_count' => $filter['record_count'],'query'=>$query);
    return $arr;
}

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