我有一个使用Closure
Table方法保存分层数据的MySQL数据库。这个问题后面有一个简单的示例数据库创建脚本。目前，我的问题是如何以正确的顺序将数据从数据库中拉出？我当前正在使用以下select语句。

SELECT `TreeData`.`iD`, `TreeData`.`subsectionOf`,
       CONCAT(REPEAT('-', `TreePaths`.`len`),`TreeData`.`name`),
       `TreePaths`.`len`,`TreePaths`.`ancestor`,`TreePaths`.`descendant`
FROM `TreeData`
LEFT JOIN `TreePaths` ON `TreeData`.`iD` = `TreePaths`.`descendant`
WHERE `TreePaths`.`ancestor` = 1
ORDER BY `TreeData`.`subsectionOrder`

它会提取正确的信息，但顺序不正确。

示例数据库创建带有示例数据的脚本。

-- Simple Sample
SET FOREIGN_KEY_CHECKS=0;
DROP TRIGGER IF EXISTS Tree_Insert;
DROP TRIGGER IF EXISTS Tree_Update;
DROP TABLE IF EXISTS TreePaths;
DROP TABLE IF EXISTS TreeData;
SET FOREIGN_KEY_CHECKS=1;


CREATE TABLE `TreeData` (
    `iD`              INT NOT NULL,             -- PK
    `subsectionOf`    INT,                      -- Parent ID & FK
    `subsectionOrder` INT,                      -- Oder of Subsections 
    `name`            NVARCHAR(500) NOT NULL,   -- Name for the entry
    PRIMARY KEY (`iD`),
    FOREIGN KEY (`subsectionOf`) REFERENCES TreeData(`iD`) ON DELETE CASCADE,
    INDEX(`name`)
) ENGINE = MYISAM;

-- Trigger to update the EntryPaths table for new entries
DELIMITER //
CREATE TRIGGER `Tree_Insert` AFTER INSERT ON `TreeData` FOR EACH ROW 
BEGIN
    INSERT INTO `TreePaths` (`ancestor`, `descendant`, `len`)
        SELECT `ancestor`, NEW.`iD`, len + 1 FROM `TreePaths`
            WHERE `descendant` = NEW.`subsectionOf`
            UNION ALL SELECT NEW.`iD`, NEW.`iD`, 0;
END; //
DELIMITER ;


DELIMITER //
CREATE TRIGGER `Tree_Update` BEFORE UPDATE ON `TreeData` FOR EACH ROW 
BEGIN
    -- From http://www.mysqlperformanceblog.com/2011/02/14/moving-subtrees-in-closure-table/
    IF OLD.`subsectionOf` != NEW.`subsectionOf` THEN
        -- Remove the node from its current parent
        DELETE a FROM `TreePaths` AS a
        JOIN `TreePaths` AS d ON a.`descendant` = d.`descendant`
        LEFT JOIN `TreePaths` AS x
        ON x.`ancestor` = d.`ancestor` AND x.`descendant` = a.`ancestor`
        WHERE d.`ancestor` = OLD.`iD` AND x.`ancestor` IS NULL;

        -- Add the node to its new parent
        INSERT `TreePaths` (`ancestor`, `descendant`, `len`)
        SELECT supertree.`ancestor`, subtree.`descendant`, supertree.`len`+subtree.`len`+1
        FROM `TreePaths` AS supertree JOIN `TreePaths` AS subtree
        WHERE subtree.`ancestor` = OLD.`iD`
        AND supertree.`descendant` = NEW.`subsectionOf`;
    END IF;
END; //
DELIMITER ;


CREATE TABLE `TreePaths` (
    `ancestor`      INT NOT NULL,
    `descendant`    INT NOT NULL,
    `len`           INT NOT NULL,
    PRIMARY KEY (`ancestor`, `descendant`),
    FOREIGN KEY (`ancestor`) REFERENCES TreeData(`iD`) ON DELETE CASCADE,
    FOREIGN KEY (`descendant`) REFERENCES TreeData(`iD`) ON DELETE CASCADE
) ENGINE = MYISAM;

INSERT INTO `TreeData` VALUES(1, NULL, NULL, 'Root A');
INSERT INTO `TreeData` VALUES(2, 1, 1, 'Item 1');
INSERT INTO `TreeData` VALUES(3, 1, 2, 'Item 2');
INSERT INTO `TreeData` VALUES(4, 1, 3, 'Item 3');
INSERT INTO `TreeData` VALUES(5, 2, 2, 'Item 1 Sub Item 2');
INSERT INTO `TreeData` VALUES(6, 2, 1, 'Item 1 Sub Item 1');
INSERT INTO `TreeData` VALUES(7, 1, 3, 'Item 4');
INSERT INTO `TreeData` VALUES(8, 4, 1, 'Item 3 Sub Item 1');
INSERT INTO `TreeData` VALUES(9, 4, 2, 'Item 3 Sub Item 2');
INSERT INTO `TreeData` VALUES(10, NULL, NULL, 'Root B');
INSERT INTO `TreeData` VALUES(11, 10, 1, 'Item A');
INSERT INTO `TreeData` VALUES(12, 10, 2, 'Item B');
INSERT INTO `TreeData` VALUES(13, 10, 3, 'Item C');