我想将我的类别列表优先存储在数据库中。。。像
cat_id cat_name cat_priority
---------------------------------
1 Test1 1
2 Test2 2
3 Test3 3
4 Test4 4
现在，如果我必须将Test1优先级设置为3。。那么Test3上会有冲突。现在，再次如果我想将Test2优先级设置为4，那么我如何根据优先级系统通过php获取数据。。它将如何工作，以及我需要在表结构中更改什么。。
每次您想要更改项目优先级时，都必须为每个项目重新分配优先级。我想你不想要重复的优先级。
//$category = ...
//get all categories
$categories = $this->db->order_by('cat_priority')->select('cat_id, cat_priority')->get();
$cat_to_change = $category['cat_id'];
$new_priority = 2;
$i_priority = 0;
$new_categories = array();
foreach($categories->result_array() as $row)
{
//this is the category we want to change, so change it
if($row['cat_id'] == $cat_to_change)
{
$row['cat_priority'] = $new_priority;
}
else
{
//increment the priority
$i_priority++;
//the new priority is owned by another cat
//so let it for the cat we want for him
if($row['cat_priority'] == $new_priority)
$i_priority++;
$row['cat_priority'] = $i_priority;
}
$new_categories[] = $row;
}
//save
$this->db->update_batch('categories', $new_categories, 'cat_id');
没有测试。希望有帮助。