什么是左右值无限级分类:
左右值无限级分类,也称为预排序树无限级分类,是一种有序的树状结构,位于这些树状结构中的每一个节点都有一个“左值”和“右值”,其规则是:每一个后代节 点的左值总是大于父类,右值总是小于父级,右值总是小于左值。处于这些结 构中的每一个节点,都可以轻易的算出其祖先或后代节点。因此,可以用它来实现无限分类。优点:通过一条SQL就可以获取所有的祖先或后代,这在复杂的分类中非常必要,通过简单的四则运算就可以得到后代的数量.由于这种方法不使用递归查询算法,有更高的查询效率,采用左右值编码的设计方案,在进行类别树的遍历时,由于只需进行2次查询,消除了递归,再加上查询条件都为数字比较,效率极高。这种算法比较高端,是mysql官方推荐的算法
1. 测试数据准备
CREATE TABLE `tree` ( `id` int(10) NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL, `lft` int(10) NOT NULL DEFAULT '0' COMMENT '左节点', `rgt` int(10) NOT NULL DEFAULT '0' COMMENT '右节点', `status` int(1) NOT NULL DEFAULT '0' COMMENT '逻辑删除 1是 0否', PRIMARY KEY (`id`), KEY `lft` (`lft`), KEY `rgt` (`rgt`), KEY `status` (`status`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; insert into tree value (null,'Food',1,18,0); insert into tree value (null,'Fruit',2,11,0); insert into tree value (null,'Red',3,6,0); insert into tree value (null,'Cherry',4,5,0); insert into tree value (null,'Yellow',7,10,0); insert into tree value (null,'Banana',8,9,0); insert into tree value (null,'Meat',12,17,0); insert into tree value (null,'Beef',13,14,0); insert into tree value (null,'Pork',15,16,0);
我们首先将多级数据按照下面的方式画在纸上
1 Food 18 | +------------------------------+ | | 2 Fruit 11 12 Meat 17 | | +-------------+ +------------+ | | | | 3 Red 6 7 Yellow 10 13 Beef 14 15 Pork 16 | | 4 Cherry 5 8 Banana 9
2. 插入分类思路
两种情况:插入最顶级节点:它的左右值与该树中最大的右值有关:左值=1,右值=最大右值+2
插入子节点:它的左右值与它的父级有关:左值=父级的右值,右值=当前的左值+1,这时要更新的数据有:父级的右值,所有左值大于父级左级,右值大于低级右值的节点左右值都应该+2;
3. 获取所有的后代节点
从图中可以看出找出某个节点的所有子节点,lft 大于左值 rgt 小于右值SELECT * FROM tree WHERE lft>2 AND rgt<11;
这个查询得到了以下的结果。
+------------+-----+-----+ | name | lft | rgt | +------------+-----+-----+ | Red | 3 | 6 | | Cherry | 4 | 5 | | Yellow | 7 | 10 | | Banana | 8 | 9 | +------------+-----+-----+
4. 计算所有子类的数量
每有子类节点中每个节点占用两个值,而这些值都是不一样且连续的,那些就可以计算出子代的数量=(右值-左值-1)/2。减少1的原因是排除该节点,你可以想像一个,一个单节点,左值是1,右值是2,没有子类节点,而这时它的右值-左值=1.
5. 检索单一路径
如果我们想知道Cherry 的路径就利用它的左右值4和5来做一个查询。反向也是一样的唯一的区别就是排序是反向的就行了。
SELECT name FROM tree WHERE lft < 4 AND rgt >5 ORDER BY lft ASC;6. 检索所有叶子节点
要检索出叶子节点(一棵树当中没有子结点的结点,称为叶子结点),我们只要查找满足rgt=lft+1的节点
select * from tree where rgt = lft + 1;7. 获取分类的深度
SELECT node.*, (count(parent.name) - 1) AS deep FROM tree AS node,tree AS parent WHERE node.lft BETWEEN parent.lft AND parent.rgt GROUP BY node.name ORDER BY node.lft8. 检索节点的直接子节点
可以想象一下,你在零售网站上呈现电子产品的分类。当用户点击分类后,你将要呈现该分类下的产品,同时也需列出该分类下的直接子分类,而不是该分类下的全部分类。为此,我们只呈现该节点及其直接子节点,不再呈现更深层次的节点.如上述获取深度的例子,可以根椐深度来小于等于1获得直接子节点
SELECT * FROM (sql7) AS a WHERE a.deep<= 1;
拿到Fruit的指定一级深度的子分类
SELECT * FROM (sql7) AS tt WHERE tt.lft>2 AND tt.rgt<11 AND tt.deep=2 ORDER BY lft
移动节点及其子节点至节点A下?
设该节点左值$lft , 右值$rgt,其子节点的数目为$count = ($rgt - $lft -1 )/2 , 节点A左值为$A_lft ,
UPDATE `tree` SET `rgt`=`rgt`-$rgt-$lft-1 WHERE `rgt`>$rgt AND `rgt`<$A_lft UPDATE `tree` SET `lft`=`lft`-$rgt-$lft-1 WHERE `lft`>$rgt AND `lft`<=$A_lft UPDATE `tree` SET `lft`=`lft`+$A_lft-$rgt , `rgt`=`rgt`+$A_lft-$rgt WHERE `lft`>=$lft AND `rgt`<=$rgt
移动多个节点;移动单个节点;删除多个节点;删除单个节点;新增节点
<?php /** *用于移动一个节点(包括子节点) * @param array $pdata = array('id'=>主键,'root'=>名称) 二选一 父节点(为空时插入最大的父节点) * @param array $ndata = array('id'=>主键,'root'=>名称) 二选一 下一个兄弟节点(没有兄弟的时候就不用) * @param array $cdata = array('id'=>主键,'root'=>名称) 二选一 当前待移动的节点 */ function move_tree_all($pdata = array(), $ndata = array(), $cdata = array()) { $cid = $cdata['id'] ? intval($cdata['id']) : ''; $croot = $cdata['root']; if (!$cid && !$croot) return; //需自加判断 //1、cdata不能为顶级 //2、cdata不能比$pdata等级高 $adata = get_tree_all($cdata); //获取当前移动节点的所有节点 delete_tree_all($cdata, 1); //逻辑删除当前移动节点的所有节点 foreach ($adata as $k => $val) { if ($k != 0) { $pdata = array('root' => $val['parent']); insert_tree($pdata, '', $val['name'], 1); } else { //first insert_tree($pdata, $ndata, $val['name'], 1); } } } /** *用于移动一个节点(不包括子节点) * @param array $pdata = array('id'=>主键,'root'=>名称) 二选一 父节点(为空时插入最大的父节点) * @param array $ndata = array('id'=>主键,'root'=>名称) 二选一 下一个兄弟节点(没有兄弟的时候就不用) * @param array $cdata = array('id'=>主键,'root'=>名称) 二选一 当前待移动的节点 */ function move_tree_item($pdata = array(), $ndata = array(), $cdata = array()) { $cid = $cdata['id'] ? intval($cdata['id']) : ''; $croot = $cdata['root']; if (!$cid && !$croot) return; //需自加判断 //1、cdata不能为顶级 if (!$croot) { $sql = "SELECT name from tree where id = $cid"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); $croot = $row['name']; unset($sql); } delete_tree_item($cdata, 1); insert_tree($pdata, $ndata, $croot, 1); } /** *用于插入一个节点 * @param array $pdata = array('id'=>主键,'root'=>名称) 二选一 父节点(为空时插入最大的父节点) * @param array $ndata = array('id'=>主键,'root'=>名称) 二选一 下一个兄弟节点(没有兄弟的时候就不用) * @param string $name string 新插入的名称 * @param int $update 默认为空,为1时更新插入 */ function insert_tree($pdata = array(), $ndata = array(), $name, $update = '') { if (!$name) return; $pid = $pdata['id'] ? intval($pdata['id']) : ''; $proot = $pdata['root']; $nid = $ndata['id'] ? intval($ndata['id']) : ''; $nroot = $ndata['root']; //有父无兄(最小的子节点,父节点的最后一个儿子) if (($pid || $proot) && !($nid || $nroot)) { $sql = $pid ? "SELECT lft, rgt FROM tree WHERE id = '{$pid}';" : "SELECT lft, rgt FROM tree WHERE name = '{$proot}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); unset($sql); //新节点 $lft = $row['rgt']; $rgt = $lft + 1; if (!$update) { $sql = "insert into tree values (null,'{$name}',$lft,$rgt,0);"; $sql1 = "update tree set rgt = rgt+2 where rgt >= {$row['rgt']}"; $sql2 = "update tree set lft = lft+2 where lft >= {$row['rgt']}"; } else { $sql = "update tree set lft=$lft,rgt=$rgt,status=0 where name ='{$name}';"; $sql1 = "update tree set rgt = rgt+2 where status =0 and rgt >= {$row['rgt']}"; $sql2 = "update tree set lft = lft+2 where status =0 and lft >= {$row['rgt']}"; } mysql_query($sql1); mysql_query($sql2); mysql_query($sql); //last add new data } //有父有兄 if (($pid || $proot) && ($nid || $nroot)) { $sql = $nid ? "SELECT lft, rgt FROM tree WHERE id = '{$nid}';" : "SELECT lft, rgt FROM tree WHERE name = '{$nroot}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); unset($sql); //新节点 $lft = $row['lft']; $rgt = $lft + 1; if (!$update) { $sql = "insert into tree values (null,'{$name}',$lft,$rgt,0);"; $sql1 = "update tree set rgt = rgt+2 where rgt >= {$row['lft']};"; $sql2 = "update tree set lft = lft+2 where lft >= {$row['lft']};"; } else { $sql = "update tree set lft=$lft,rgt=$rgt,status=0 where name ='{$name}';"; $sql1 = "update tree set rgt = rgt+2 where status = 0 and rgt >= {$row['lft']};"; $sql2 = "update tree set lft = lft+2 where status = 0 and lft >= {$row['lft']};"; } mysql_query($sql1); mysql_query($sql2); mysql_query($sql); //last add new data } //无父无兄(大佬) if (!($pid || $proot) && !($nid || $nroot)) { $sql = "SELECT max(`rgt`) as rgt FROM tree;"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); unset($sql); //新节点 $lft = 1; $rgt = $row['rgt'] + 2; if (!$update) { $sql = "insert into tree values (null,'{$name}',$lft,$rgt,0);"; $sql1 = "update tree set rgt = rgt+1"; $sql2 = "update tree set lft = lft+1"; } else { $sql = "update tree set lft=$lft,rgt=$rgt,status=0 where name ='{$name}';"; $sql1 = "update tree set rgt = rgt+1 where status = 0"; $sql2 = "update tree set lft = lft+1 where status = 0"; } mysql_query($sql1); mysql_query($sql2); mysql_query($sql); //last add new data } } /** *用于删除一个节点(包括子节点) * @param array $data = array('id'=>主键,'root'=>名称) 二选一 * @param int $update 默认为空,为1时逻辑删除 */ function delete_tree_all($data, $update = '') { $id = $data['id'] ? intval($data['id']) : ''; $root = $data['root']; if (!$id && !$root) return; $sql = $id ? "SELECT lft, rgt FROM tree WHERE id = '{$id}';" : "SELECT lft, rgt FROM tree WHERE name = '{$root}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); unset($sql); $middle = $row['rgt'] - $row['lft'] + 1; if (!$update) { $sql = "delete from tree where lft BETWEEN '" . $row['lft'] . "' AND '" . $row['rgt'] . "'"; $sql1 = "update tree set rgt = rgt-{$middle} where rgt > {$row['rgt']}"; $sql2 = "update tree set lft = lft-{$middle} where lft > {$row['rgt']}"; } else { $sql = "update tree set status = 1 where lft BETWEEN '" . $row['lft'] . "' AND '" . $row['rgt'] . "'"; $sql1 = "update tree set rgt = rgt-{$middle} where status=0 and rgt > {$row['rgt']}"; $sql2 = "update tree set lft = lft-{$middle} where status=0 and lft > {$row['rgt']}"; } mysql_query($sql); mysql_query($sql1); mysql_query($sql2); } /** *用于删除一个节点(不包括子节点) * @param array $data = array('id'=>主键,'root'=>名称) 二选一 * @param int $update 默认为空,为1时逻辑删除 */ function delete_tree_item($data, $update = '') { $id = $data['id'] ? intval($data['id']) : ''; $root = $data['root']; if (!$id && !$root) return; $sql = $id ? "SELECT id,lft, rgt FROM tree WHERE id = '{$id}';" : "SELECT id,lft, rgt FROM tree WHERE name = '{$root}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); unset($sql); if (!$update) { $sql = "delete from tree where id = {$row['id']};"; $sql1 = "update tree set rgt = rgt-1,lft = lft -1 where lft > {$row['lft']} and rgt < {$row['rgt']}"; $sql2 = "update tree set lft = lft-2 where lft > {$row['rgt']}"; $sql3 = "update tree set rgt = rgt-2 where rgt > {$row['rgt']}"; } else { $sql = "update tree set status = 1 where id = {$row['id']};"; $sql1 = "update tree set rgt = rgt-1,lft = lft -1 where status = 0 and lft > {$row['lft']} and rgt < {$row['rgt']}"; $sql2 = "update tree set lft = lft-2 where status = 0 and lft > {$row['rgt']}"; $sql3 = "update tree set rgt = rgt-2 where status = 0 and rgt > {$row['rgt']}"; } mysql_query($sql); mysql_query($sql1); //can do or not do just right,but not do load empty 2 number in middle mysql_query($sql2); mysql_query($sql3); } /** *用于获取所有的节点 * @param array $data = array('id'=>主键,'root'=>名称) 二选一 */ function get_tree_all($data) { $id = $data['id'] ? intval($data['id']) : ''; $root = $data['root']; if (!$id && !$root) return; $sql = $id ? "SELECT lft, rgt FROM tree WHERE id = '{$id}';" : "SELECT lft, rgt FROM tree WHERE name = '{$root}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); $adata = array(); //所有数据 $right = array(); //计数 $prev = array(); $result = mysql_query("SELECT id,name, lft, rgt FROM tree WHERE lft BETWEEN '" . $row['lft'] . "' AND '" . $row['rgt'] . "' ORDER BY lft ASC ;"); while ($row = mysql_fetch_assoc($result)) { if (count($right) > 0) { while ($right[count($right) - 1] < $row['rgt']) { // 检查我们是否应该将节点移出堆栈 array_pop($right); array_pop($prev); } } $parent = $prev ? end($prev) : ''; $adata[] = array('id' => $row['id'], 'name' => $row['name'], 'level' => count($right), 'parent' => $parent); $right[] = $row['rgt']; $prev[] = $row['name']; } return $adata; } /** *用于展示分类 * @param array $data = array('id'=>主键,'root'=>名称) 二选一 */ function display_tree($data) { $id = $data['id'] ? intval($data['id']) : ''; $root = $data['root']; if (!$id && !$root) return; $sql = $id ? "SELECT lft, rgt FROM tree WHERE id = '{$id}';" : "SELECT lft, rgt FROM tree WHERE name = '{$root}';"; $result = mysql_query($sql); $row = mysql_fetch_assoc($result); $right = array(); $result = mysql_query("SELECT name, lft, rgt FROM tree WHERE lft BETWEEN '" . $row['lft'] . "' AND '" . $row['rgt'] . "' ORDER BY lft ASC ;"); while ($row = mysql_fetch_assoc($result)) { if (count($right) > 0) { // 检查我们是否应该将节点移出堆栈 while ($right[count($right) - 1] < $row['rgt']) { array_pop($right); } } echo str_repeat('--', count($right)) . $row['name'] . "<br/>"; $right[] = $row['rgt']; } } mysql_connect('localhost', 'root', 'orbit') or die('connect error'); mysql_select_db('test') or die('database error'); mysql_query('set names utf8'); //display_tree(array('root' => 'Food')); //display_tree(array('root'=>'bigboss')); //move_tree_all($pdata=array('root'=>'Fruit'),$ndata=array('root'=>'Red'),$cdata=array('root'=>'Meat')); //move_tree_all('','',$cdata=array('root'=>'Meat')); //move_tree_item('','',array('root'=>'Red')); //move_tree_item(array('root'=>'Red'),array('root'=>'Cherry'),array('root'=>'Fruit')); //delete_tree_all(array('root'=>'Yellow')); //delete_tree_all(array('root'=>'Meat')); //delete_tree_item(array('root'=>'Meat')); //insert_tree('','','bigboss'); //insert_tree(array('root'=>'Red'),'','dalao'); //insert_tree(array('root'=>'Red'),array('root'=>'Cherry'),'baddalao'); //insert_tree(array('root'=>'Fruit'),array('root'=>'Red'),'Redbother');
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NULL 博文链接:https://shirne.iteye.com/blog/1226758
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