MySQL分层数据帮助——闭表法

Question

我正在尝试在 MySQL 中实现一个系统来存储分层数据。我决定使用实现的系统 here如 Bill Karwin 所述从第 40 张幻灯片开始。我正在尝试设置数据库，以便自动维护 EntryPaths 表。

更新:我已经更新了一些数据库创建 SQL。我认为我有 1/2 的工作用于更新。运行数据库后创建 SQL 尝试以下操作

先看看这个条目长什么样

-- Example query to return a full library entry (0x02 is the entry iD)
SELECT `Library`.* FROM `Library`
LEFT JOIN `EntryPaths` ON `Library`.`iD` = `EntryPaths`.`descendant`
WHERE `EntryPaths`.`ancestor` = 0x02
ORDER BY `Library`.`subsectionOf`, `Library`.`subsectionOrder`

这个看起来怎么样

-- Example query to return a full library entry (0x08 is the entry iD)
SELECT `Library`.* FROM `Library`
LEFT JOIN `EntryPaths` ON `Library`.`iD` = `EntryPaths`.`descendant`
WHERE `EntryPaths`.`ancestor` = 0x08
ORDER BY `Library`.`subsectionOf`, `Library`.`subsectionOrder`

查看的第一个条目有几个 child ，第二个没有 child 。运行以下更新以将“College Years”节点(及其子节点)重新设置为 John Doe

UPDATE  `Library` SET  `subsectionOf` =  0x08 WHERE  `Library`.`iD` = 0x04;

如果您重新运行上面的两个选择语句，您会看到项目已从 Jane Doe 中删除，但它们没有按预期添加到 John Doe . Library_Update 触发器有问题，但我已经没有办法修复它了。

数据库使用示例数据创建SQL:

-- MYSQL
SET FOREIGN_KEY_CHECKS=0;
DROP TRIGGER IF EXISTS Library_Insert;
DROP TRIGGER IF EXISTS Library_Update;
DROP TABLE IF EXISTS Users;
DROP TABLE IF EXISTS Attributes;
DROP TABLE IF EXISTS LibraryHistory;
DROP TABLE IF EXISTS EntryPaths;
DROP TABLE IF EXISTS Library;
SET FOREIGN_KEY_CHECKS=1;


CREATE TABLE `Users` (
    `iD`              VARBINARY(16) NOT NULL,   -- UUID & PK
    `libraryID`       VARBINARY(16),            -- Library UUID & FK (The library entry for this person)
    `email`           NVARCHAR(255) NOT NULL,   -- Email address
    `nickname`        NVARCHAR(255) NOT NULL,   -- Nickname used for display
    `firstname`       NVARCHAR(255),            -- Real first name
    `lastname`        NVARCHAR(255),            -- Real last name
    `joinDate`        DATETIME NOT NULL,        -- Date the account was created
    PRIMARY KEY (`iD`)
) ENGINE = MYISAM;


CREATE TABLE `Library` (
    `iD`              VARBINARY(16) NOT NULL,   -- UUID & PK
    `name`            NVARCHAR(500) NOT NULL,   -- Name for the entry
    `contentType`     NVARCHAR(50)  NOT NULL,   -- Mime type of data
    `content`         LONGBLOB      NOT NULL,   -- Data a for the entry
    `subsectionOf`    VARBINARY(16),            -- Library UUID & FK
    `subsectionOrder` INT,                      -- Oder of Subsections 
    `lastModifiedBy`  VARBINARY(16),            -- User UUID & FK
    `lastModified`    DATETIME      NOT NULL,   -- Last time the record was updated
    PRIMARY KEY (`iD`),
    FOREIGN KEY (`subsectionOf`) REFERENCES Library(`iD`) ON DELETE CASCADE,
    FOREIGN KEY (`lastModifiedBy`) REFERENCES Users(`iD`),
    INDEX(`name`)
) ENGINE = MYISAM;

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


DELIMITER //
CREATE TRIGGER `Library_Update` BEFORE UPDATE ON `Library` FOR EACH ROW 
BEGIN
    -- Add the old entry into the history table
    INSERT INTO `LibraryHistory` VALUES(UNHEX(REPLACE(UUID(),'-','')),
        OLD.`iD`, OLD.`name`, OLD.`contentType`, OLD.`content`,
        OLD.`subsectionOf`, OLD.`subsectionOrder`, OLD.`lastModifiedBy`,
        OLD.`lastModified`);

    -- 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 `EntryPaths` AS a
        JOIN `EntryPaths` AS d ON a.`descendant` = d.`descendant`
        LEFT JOIN `EntryPaths` 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
        -- FIXME: Not Working yet
        INSERT `EntryPaths` (`ancestor`, `descendant`, `len`)
        SELECT supertree.`ancestor`, subtree.`descendant`, supertree.`len`+subtree.`len`+1
        FROM `EntryPaths` AS supertree JOIN `EntryPaths` AS subtree
        WHERE subtree.`ancestor` = NEW.`iD`
        AND supertree.`descendant` = NEW.`subsectionOf`;
    END IF;
END; //
DELIMITER ;


CREATE TABLE `EntryPaths` (
    `ancestor`      VARBINARY(16) NOT NULL,
    `descendant`    VARBINARY(16) NOT NULL,
    `len`           VARBINARY(16) NOT NULL,
    PRIMARY KEY (`ancestor`, `descendant`),
    FOREIGN KEY (`ancestor`) REFERENCES Library(`iD`) ON DELETE CASCADE,
    FOREIGN KEY (`descendant`) REFERENCES Library(`iD`) ON DELETE CASCADE
) ENGINE = MYISAM;


CREATE TABLE `LibraryHistory` (
    `iD`              VARBINARY(16) NOT NULL,   -- UUID & PK
    `libraryID`       VARBINARY(16) NOT NULL,   -- Library UUID & FK
    `name`            NVARCHAR(500) NOT NULL,   -- Name for the entry
    `contentType`     NVARCHAR(50)  NOT NULL,   -- Mime type of data
    `content`         LONGBLOB      NOT NULL,   -- Data a for the entry
    `subsectionOf`    VARBINARY(16),            -- Library UUID & FK
    `subsectionOrder` INT,                      -- Oder of Subsections 
    `lastModifiedBy`  VARBINARY(16),            -- User UUID & FK
    `lastModified`    DATETIME      NOT NULL,   -- Last time the record was updated
    PRIMARY KEY (`iD`),
    FOREIGN KEY (`libraryID`) REFERENCES Library(`iD`) ON DELETE CASCADE,
    FOREIGN KEY (`lastModifiedBy`) REFERENCES Users(`iD`)
) ENGINE = MYISAM;


CREATE TABLE `Attributes` (
    `iD`              VARBINARY(16) NOT NULL,  -- UUID & PK  (Potentially could be removed)
    `libraryID`       VARBINARY(16) NOT NULL,  -- Library UUID & FK
    `name`            NVARCHAR(500) NOT NULL,  -- Name of attribute
    `dataType`        INT           NOT NULL,  -- The type of data the attribute holds (int, date, string, etc.)
    `data`            NVARCHAR(500) NOT NULL,  -- Value of attribute
    `lastModifiedBy`  VARBINARY(16),           -- User UUID & FK
    `lastModified`    DATETIME      NOT NULL,  -- Last time the record was updated
    PRIMARY KEY (`iD`),
    FOREIGN KEY (`libraryID`) REFERENCES Library(`iD`) ON DELETE CASCADE,
    INDEX (`name`)
) ENGINE = MYISAM;

ALTER TABLE `Users` ADD CONSTRAINT FK_User_Library FOREIGN KEY (`libraryID`) REFERENCES Library(`iD`);

-- Example Data
INSERT INTO `Library` VALUES(0x01, 'People', 'text/plain', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:27:54');
INSERT INTO `Library` VALUES(0x02, 'Jane Doe', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:29:13');
INSERT INTO `Library` VALUES(0x03, 'Younger Years', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', 0x02, 1, NULL, '2011-11-16 00:00:00');
INSERT INTO `Library` VALUES(0x04, 'College Years', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', 0x02, 2, NULL, '2011-11-16 20:31:52');
INSERT INTO `Library` VALUES(0x05, 'Yale', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', 0x04, 2, NULL, '2011-11-16 20:32:44');
INSERT INTO `Library` VALUES(0x06, 'Old Age', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar find me here scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', 0x02, 3, NULL, '2011-11-16 20:31:52');
INSERT INTO `Library` VALUES(0x07, 'Community College', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', 0x04, 1, NULL, '2011-11-16 20:33:11');
INSERT INTO `Library` VALUES(0x08, 'John Doe', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:34:40');
INSERT INTO `Library` VALUES(0x09, 'Planets', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:27:54');
INSERT INTO `Library` VALUES(0x10, 'Earth', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:27:54');
INSERT INTO `Library` VALUES(0x11, 'Mars', 'text/x-markup', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam pulvinar scelerisque quam, vel convallis turpis porttitor in. Curabitur pulvinar fermentum pulvinar. Mauris lorem lacus, gravida porta lacinia vitae, dictum ac eros. Aliquam magna arcu, lacinia ac dictum sed, euismod eu elit. Sed semper nulla at velit pulvinar in vehicula risus tempus. Phasellus id nisl libero, id porttitor purus. Integer aliquet semper aliquam. Morbi elit mi, pellentesque et ornare nec, iaculis gravida elit. Sed in luctus lorem. Maecenas a purus at lectus condimentum congue.', NULL, NULL, NULL, '2011-11-16 20:27:54');
INSERT INTO `Attributes` VALUES(0x01, 0x02, 'TypeOf', 1, 0x01, NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x02, 0x02, 'BirthDate', 2, '19770521', NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x03, 0x02, 'EyeColor', 3, 'Brown', NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x04, 0x08, 'TypeOf', 1, 0x01, NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x05, 0x08, 'BirthDate', 2, '19740521', NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x06, 0x10, 'TypeOf', 1, 0x08, NULL, '2011-11-16 20:34:40');
INSERT INTO `Attributes` VALUES(0x07, 0x11, 'TypeOf', 1, 0x08, NULL, '2011-11-16 20:34:40');

Answer 1

在 Libary_Update 触发器的 INSERT 语句中，您有以下行:

WHERE subtree.`ancestor` = NEW.`iD`

但您没有更新 ID 字段，所以我认为您不会有 NEW.iD 值。该行是否应该改用 OLD.iD？