MYSQL：選擇父級按字母順序分組的按字母順序排序的兒童

Question

我已經制作了一個簡單的表來了解親子關係，但我似乎沒有得到正確的結果。我想按字母順序「名稱」字段中，只有那些誰沒有父母（PARENT_ID == 0）

，但只要有子行父，他們應打印後

1. 第一排序呢父母也按姓名按字母順序排序。

實施例的表：

===================================== =======================

CREATE TABLE IF NOT EXISTS `test` (
    `id` int(11) NOT NULL AUTO_INCREMENT, 
    `parent_id` int(11) NOT NULL DEFAULT '0', 
    `name` varchar(255) NOT NULL, 
    PRIMARY KEY (`id`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=9 ; 

-- 
-- Dumping data for table `test` 
-- 

INSERT INTO `test` (`id`, `parent_id`, `name`) VALUES 
(1, 4, 'Zorg'), 
(2, 0, 'Woordolack'), 
(3, 4, 'Akriller'), 
(4, 0, 'Metabrusher'), 
(5, 2, 'Intersplitter'), 
(6, 0, 'Beaverbrain'), 
(7, 4, 'Torgeoruos'), 
(8, 2, 'Deptezaurus'); 

==================== ========================================

這是我想要的使用PHP輸出到Web瀏覽器：

Beaverbrain 
Metabrusher 
-> Akriller 
-> Torgeoruos 
-> Zorg 
Woordolack 
-> Deptezaurus 
-> Intersplitter 

================================================ ============

我應該說這是一個示例表，只是爲了展示這個想法，所以可以通過任何方式修改它以獲得正確的結果。

Answer 1

你可以試試這個查詢

SELECT IF(child = '',parent,CONCAT('->',child)) as value 
FROM 
    (SELECT parent.name as parent,child.name as child 
    FROM test parent 
     INNER JOIN 
     (SELECT id,parent_id,name FROM test 
     UNION 
     SELECT null,id,'' FROM test 
     WHERE parent_id = 0)child 
    WHERE parent.parent_id = 0 
    AND child.parent_id = parent.id 
    ORDER BY parent,child 
    )parent_child 

sqlFiddle

什麼查詢確實是INNER JOIN試驗與測試，並找出哪些是父母和孩子。內部UNION SELECT null,id,'' FROM test WHERE parent_id = 0創建一個空的子（ren）用於顯示目的。然後，外部SELECT會查看孩子是否「打印出父母」，否則在孩子面前連接->。所以你得到你想要的結果。

以下版本可能會快一點。由於我們只是用NULL子代創建父項，而不是使用子項作爲INNER JOIN（上圖）的一部分。

SELECT IF(child IS NULL,parent,CONCAT('->',child)) as value 
FROM 
(SELECT parent.name as parent,child.name as child 
    FROM test parent 
    INNER JOIN test child ON child.parent_id = parent.id 
    WHERE parent.parent_id = 0 
    UNION 
    SELECT test.name as parent,NULL as child #This creates a NULL child row 
    FROM test WHERE test.parent_id = 0  #for parent display purpose 
    ORDER BY parent,child 
)parent_child 

sqlFiddle

但是我會用下面的查詢，而不是和PHP內，檢查，看看是否isParent標誌是1或0，然後顯示相應的字段。

SELECT 0 as isParent,parent.name as parent,child.name as child, 
     parent.id as parentId,child.id as childId 
    FROM test parent 
INNER JOIN test child ON child.parent_id = parent.id 
WHERE parent.parent_id = 0 
UNION 
SELECT 1 as isParent,test.name as parent,NULL as child, 
     test.id as parentId,NULL as childId 
    FROM test WHERE test.parent_id = 0  
ORDER BY parent,child 

sqlFiddle

Answer 2

在管理層次數據，你可以用一個簡單的PHP遞歸函數代替，

function DisplayTree($parent , $depth)  {                          
    $sql = $this->db->query("SELECT id,name FROM '$table' WHERE parent_id = '$parent'"); 

     foreach($sql->result() as $field) { 
     print "<fieldset style=\"margin-left:$depth%; width:300px\">"; 
      print $field->name; 
     print "</fieldset>"; 

     $this->DisplayTree($field->code , $depth+8);   
    } 

    } 

Answer 3

使用一對情侶在PHP簡單的查詢，

$r1 = $db->query("select * from test where parent_id = 0 order by name asc") or die('err in q1'); 
    while($arr1 = $r1->fetch_assoc()){ 
      $parent = $arr1['name']; 
      $parent_id = $arr1['id']; 
      echo $parent 
      $r2 = $db->query("select * from test where parent_id = $parent order by name asc") or die('err in q2'); 
      while($arr2 = $r2->fetch_assoc()){ 
       $child = $arr2['name']; 
       echo $child."<br />"; 
      } 
    } 

Answer 4

試試這個解決方案：

SELECT 
    A.id, 
    A.name 
FROM 
    `test` AS A LEFT JOIN `test` AS B ON A.`parent_id` = B.`id` 
GROUP BY 
    A.`id` 
ORDER BY 
    IFNULL(B.`name`, A.`name`), 
    COALESCE(A.`parent_id`, A.`id`), 
    A.`parent_id` != 0, 
    A.`name`;