Php 选择表中的术语(类别)并在选择框中输出它们
这是我的术语表类别的数据库结构:Php 选择表中的术语(类别)并在选择框中输出它们,php,mysql,list,select,taxonomy,Php,Mysql,List,Select,Taxonomy,这是我的术语表类别的数据库结构: id | name | parent_id | level | position -------------------------------------------------------------- 1 | term 1 | NULL | 0 | 1 2 | term 2 | 1 | 1 | 1
id | name | parent_id | level | position
--------------------------------------------------------------
1 | term 1 | NULL | 0 | 1
2 | term 2 | 1 | 1 | 1
3 | term 3 | 1 | 1 | 2
4 | term 4 | NULL | 0 | 2
5 | term 5 | 4 | 1 | 1
因此,术语2和3是1的第一级子级,而术语5是4的第一级子级
这是我的疑问:这是不正确的,这应该被修正
SELECT
`id`,
`name`
FROM
`terms`
ORDER BY
`position` ASC,
`level` ASC
这是我的php:
$terms = array();
// query part
if(!$this->_db->resultRows > 0)
return $terms;
while($d = $this->_db->fetch($r))
{
$terms[$d->id] = new Term($d->id);
}
return $terms;
当前结果:
term 1
term 2
term 5
term 4
term 3
但结果应该是:
term 1
term 2
term 3
term 4
term 5
我不知道如何修改查询以获得正确的结果
目标是将其输出到多个选择框中
我知道如何使用嵌套列表,但不能嵌套select,所以有很多方法可以解决这类问题。我将介绍的所有方法都不要求表中有level列。我认为这是多余的数据,因为它可以从其他列中找到的信息推断出来 如果您知道最大级别仅为1,则最大深度为2,您可以使用如下查询:
SELECT
t.`id`,
t.`name`,
IF(p.`position` IS NULL, t.`position`*{$row_count}, p.`position`*{$row_count}+t.`position`) AS display_order
FROM
`terms` t
LEFT JOIN `terms` p ON p.`id` = t.`parent_id`
ORDER BY
display_order
$dbh->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$sth = $dbh->prepare('SELECT id,name FROM terms WHERE parent_id IS NULL ORDER BY position');
$sth->execute(array(NULL));
$terms = $sth->fetchAll();
$sql = 'SELECT id,name FROM terms WHERE parent_id = ? ORDER BY position';
$terms_to_check = $terms;
$terms = array();
while(count($terms_to_check))
{
$k = array_shift($terms_to_check);
$terms[] = $k;
$sth = $dbh->prepare($sql);
$sth->execute(array($k['id']));
$results = $sth->fetchAll();
$terms_to_check = array_merge($results, $terms_to_check);
}
其中,计算$row_计数:
SELECT COUNT(*) FROM `terms`
有多种方法可以修改此SQL,使其能够在更高的级别和深度下工作,但查询需要在其支持的每个最大级别/深度下变得更大
如果您不确定您将拥有的级别数量,那么您可能应该执行以下操作:
SELECT
t.`id`,
t.`name`,
IF(p.`position` IS NULL, t.`position`*{$row_count}, p.`position`*{$row_count}+t.`position`) AS display_order
FROM
`terms` t
LEFT JOIN `terms` p ON p.`id` = t.`parent_id`
ORDER BY
display_order
$dbh->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$sth = $dbh->prepare('SELECT id,name FROM terms WHERE parent_id IS NULL ORDER BY position');
$sth->execute(array(NULL));
$terms = $sth->fetchAll();
$sql = 'SELECT id,name FROM terms WHERE parent_id = ? ORDER BY position';
$terms_to_check = $terms;
$terms = array();
while(count($terms_to_check))
{
$k = array_shift($terms_to_check);
$terms[] = $k;
$sth = $dbh->prepare($sql);
$sth->execute(array($k['id']));
$results = $sth->fetchAll();
$terms_to_check = array_merge($results, $terms_to_check);
}
顺便说一句,我建议使用PDO。MySQL不支持递归函数,因此它不太适合这种存储分层数据的邻接列表模型。您应该考虑使用嵌套集合或闭包表重构数据。有关更多信息,请参阅。您知道级别的限制吗?目前只有两个级别。查询是否需要处理两个以上的级别?是的,级别应该是无限的