Question

MySQL网站有关于在数据库中存储分层数据的excellent tutorial。我正在尝试编写返回节点的直接子节点的查询。我不想只是从MySQL网站复制/粘贴查询，因为我试图以数据库无关的方式处理这个问题。

这是我正在尝试Zend_Db_Select-ify

的查询

SELECT node.name, (COUNT(parent.name) - (sub_tree.depth + 1)) AS depth
FROM nested_category AS node,
    nested_category AS parent,
    nested_category AS sub_parent,
    (
        SELECT node.name, (COUNT(parent.name) - 1) AS depth
        FROM nested_category AS node,
        nested_category AS parent
        WHERE node.lft BETWEEN parent.lft AND parent.rgt
        AND node.name = 'PORTABLE ELECTRONICS'
        GROUP BY node.name
        ORDER BY node.lft
    )AS sub_tree
WHERE node.lft BETWEEN parent.lft AND parent.rgt
    AND node.lft BETWEEN sub_parent.lft AND sub_parent.rgt
    AND sub_parent.name = sub_tree.name
GROUP BY node.name
ORDER BY node.lft;

Answer 1

您可以尝试将查询拆分为两个Zend_Db_Select语句 - 父查询和子查询。您可以使用Zend_Db_Select对象作为from()方法的参数，如下所示：

$mainQuery = $db->select();
$mainQuery->from('user');

$sub = $db->select();
$sub->from('company');

$mainQuery->from(array('subquery' => $sub));

你会得到那种查询：

SELECT `user`.*, `sub`.* FROM `user` 
    INNER JOIN (
        SELECT `company`.* FROM `company`
    ) AS `sub`

如您所见，当您添加第二个INNER JOIN时，它会自动添加from() - 但我认为，您可以将查询重写为用户连接而不是语法中的多个连接。所以你应该使用joinInner()方法，因为那时你可以指定连接条件作为它的第二个参数。

请注意，子查询与主查询类似，因此您可以构建主查询，将其克隆为子查询，并且由于Zend_Db_Select可能删除不必要的部分（reset()方法）并替换它们： / p>

$mainQuery = $db->select(); //and rest
$subQuery = clone $mainQuery;
$subQuery->reset(Zend_Db_Select::WHERE);
$subQuery->where(); // and add valid conditions for subquery

Answer 2

您可以像这样直接粘贴查询

$result = $db->query("SELECT node.name, (COUNT(parent.name) - (sub_tree.depth + 1)) AS depth
        FROM nested_category AS node,
        nested_category AS parent,
        nested_category AS sub_parent,
        (
            SELECT node.name, (COUNT(parent.name) - 1) AS depth
            FROM nested_category AS node,
            nested_category AS parent
            WHERE node.lft BETWEEN parent.lft AND parent.rgt
            AND node.name = 'PORTABLE ELECTRONICS'
            GROUP BY node.name
            ORDER BY node.lft
        )AS sub_tree
    WHERE node.lft BETWEEN parent.lft AND parent.rgt
        AND node.lft BETWEEN sub_parent.lft AND sub_parent.rgt
        AND sub_parent.name = sub_tree.name
    GROUP BY node.name
    ORDER BY node.lf");

请务必使用quote()在此查询中输入您自己的任何参数。

这有点像作弊，而不是我所采用的东西。

如何将复杂的SQL查询转换为Zend_Db_Select语句？

2 个答案: