分页在一个大型系统中是必不可少的，当数据量过大时，一页显示的内容是有限的，这时我们就想把数据分页展示，下面介绍下
mysql下的分页原理，以及ecshop中的分页函数的使用。
mysql中的分页主要是通过关键词limit来实现的， limit 可以给以给起始值，然后再给一个范围，就可以逐次地取出所有的数据。
举个简单的例子：
create table user(int 10 not null auto_increment,
name varchar(20),
sex tinyint(1),
reg_time datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
创建出user表，插入测试数据。
insert into user(`name`,`sex` `reg_time`) values('zhangsan','1','2012-02-09 02:00:00);
insert into user(`name`,`sex` `reg_time`) values('zaoren','1','2012-02-09 14:00:32);
insert into user(`name`,`sex` `reg_time`) values('lily','0','2013-08-10 10:06:00);
insert into user(`name`,`sex` `reg_time`) values('lizi','0','1956-00-56 10:10:50);
insert into user(`name`,`sex` `reg_time`) values('zhangsan2','1','1999-00-34 03:08:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan3','0','1998-00-24 00:23:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan4','1','2013-00-00 00:12:00);
insert into user(`name`,`sex` `reg_time`) values('qunhao','1','2014-00-00 00:00:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan4','1','2014-10-30 09:56:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan6','1','2013-06-00 05:01:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan8','1','2016-00-00 00:00:00);
insert into user(`name`,`sex` `reg_time`) values('hongyezhang','0','2015-00-00 00:00:00);
insert into user(`name`,`sex` `reg_time`) values('zhangsan','1','2008-08-080 00:00:00);
之后通过limit就可以分批取出用户信息：
select * from `user` order by `reg_time` limit 0,5;
select * from `user` order by `reg_time` limit 5,5;
select * from `user` order by `reg_time` limit 10,5;
通过改变limit 的初始值，就可以每次取出5条数据。
下面给出ecshop中的分页页码函数：
function get_pager($url, $param, $record_count, $page = 1, $size = 10)
{
$size = intval($size);
if ($size < 1)
{
$size = 10;
}
$page = intval($page);
if ($page < 1)
{
$page = 1;
}
$record_count = intval($record_count);
$page_count = $record_count > 0 ? intval(ceil($record_count / $size)) : 1;
if ($page > $page_count)
{
$page = $page_count;
}
/* 分页样式 */
$pager['styleid'] = isset($GLOBALS['_CFG']['page_style'])? intval($GLOBALS['_CFG']['page_style']) : 0;
$page_prev = ($page > 1) ? $page - 1 : 1;
$page_next = ($page < $page_count) ? $page + 1 : $page_count;
/* 将参数合成url字串 */
$param_url = '?';
foreach ($param AS $key => $value)
{
$param_url .= $key . '=' . $value . '&';
}
$pager['url'] = $url;
$pager['start'] = ($page -1) * $size;
$pager['page'] = $page;
$pager['size'] = $size;
$pager['record_count'] = $record_count;
$pager['page_count'] = $page_count;
if ($pager['styleid'] == 0)
{
$pager['page_first'] = $url . $param_url . 'page=1';
$pager['page_prev'] = $url . $param_url . 'page=' . $page_prev;
$pager['page_next'] = $url . $param_url . 'page=' . $page_next;
$pager['page_last'] = $url . $param_url . 'page=' . $page_count;
$pager['array'] = array();
for ($i = 1; $i <= $page_count; $i++)
{
$pager['array'][$i] = $i;
}
}
else
{
$_pagenum = 10; // 显示的页码
$_offset = 2; // 当前页偏移值
$_from = $_to = 0; // 开始页, 结束页
if($_pagenum > $page_count)
{
$_from = 1;
$_to = $page_count;
}
else
{
$_from = $page - $_offset;
$_to = $_from + $_pagenum - 1;
if($_from < 1)
{
$_to = $page + 1 - $_from;
$_from = 1;
if($_to - $_from < $_pagenum)
{
$_to = $_pagenum;
}
}
elseif($_to > $page_count)
{
$_from = $page_count - $_pagenum + 1; |