1

这个问题是我的另一个问题的扩展@需要一些关于在 MySQL 中编码多：多关系的建议和反馈......

我有以下表的 MySQL 代码：

DROP TABLE IF EXISTS `person` ;
CREATE TABLE `person` (
  `personID` INT(5) NOT NULL AUTO_INCREMENT ,
  `firstName` VARCHAR(50) NOT NULL ,
  `lastName` VARCHAR(50) NOT NULL ,
  `dateOfBirth` DATE NOT NULL ,
  `personType` CHAR(6) NOT NULL, 
  `photo` BLOB NULL DEFAULT NULL ,
  PRIMARY KEY (`personID`))
ENGINE = InnoDB;
SHOW WARNINGS;

DROP TABLE IF EXISTS `parent` ;
CREATE TABLE `parent` (
  `parentID` INT(5) NOT NULL,
  PRIMARY KEY (`parentID`), 
  FOREIGN KEY (`parentID`) REFERENCES `person` (`personID`) 
  ON DELETE CASCADE 
  ON UPDATE CASCADE)
ENGINE = InnoDB;
SHOW WARNINGS;

DROP TABLE IF EXISTS `player` ;
CREATE TABLE Player (
    `playerID` INT(5) NOT NULL,
    `motherID` INT(5),
    `fatherID` INT(5),
    `schoolID` INT(5),
    PRIMARY KEY (`playerID`), 
    FOREIGN KEY (`playerID`) REFERENCES `person` (`personID`) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE,
    FOREIGN KEY (`motherID`) REFERENCES `parent` (`parentID`) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE,
    FOREIGN KEY (`fatherID`) REFERENCES `parent` (`parentID`) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE, 
    FOREIGN KEY (`schoolID`) REFERENCES `school` (`schoolID`) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE)
ENGINE = InnoDB;
SHOW WARNINGS;

我想格式化查询，使其返回如下信息：

+----------+-----------------+----------------+-----------------+----------------+
| ParentID | ParentFirstName | ParentLastName | PlayerFirstName | PlayerLastName |
+----------+-----------------+----------------+-----------------+----------------+
|        1 | John            | Doe            | Maggie          | Doe            |
|        1 | John            | Doe            | Rob             | Doe            |
|        2 | Jane            | Doe            | Rob             | Doe            |
|        2 | Jane            | Doe            | Maggie          | Doe            |
|        3 | Peter           | Smith          | Neil            | Smith          |
|        3 | Peter           | Smith          | Chad            | Smith          |
|        4 | Mary            | Mason          | Neil            | Smith          |
|        4 | Mary            | Mason          | Chad            | Smith          |
+----------+-----------------+----------------+-----------------+----------------+

我注意到在上面的可视化中名称重复了好几次，我还想知道使用 GROUP_CONCAT 以某种方式将它们合并在一起是否是个好主意。

我无法以生成所需查询的方式连接这三个表。我在http://sqlfiddle.com/#!2/baf8d找到了我发现的一些灵感（此处由用户提供），但是我无法根据自己的需要定制它（在示例中的第一个和最后一个名称在每个父/玩家表中，而我从 Person 超类继承这些字段。

下面的代码是我在决定在这里提问之前得到的最接近的代码。我想如果我可以将这些查询合并在一起以匹配上面的结果，但我被困住了......

mysql> select person.firstName as ParentFirstName, person.lastName as ParentLastName from person where
    -> person.personID IN (select * from parent);
+-----------------+----------------+
| ParentFirstName | ParentLastName |
+-----------------+----------------+
| John            | Doe            |
| Jane            | Doe            |
| Peter           | Smith          |
| Mary            | Mason          |
+-----------------+----------------+

mysql> select person.firstName as ChildFirstName, person.lastName as ChildLastName from person where
    -> person.personID IN (select player.playerID from player);
+----------------+---------------+
| ChildFirstName | ChildLastName |
+----------------+---------------+
| Maggie         | Doe           |
| Rob            | Doe           |
| Neil           | Smith         |
| Chad           | Smith         |
+----------------+---------------+

我觉得在我的数据库模式中拥有 Person 超类是必要的（因为玩家/父级和其他“人”实体会有类似的细节）而且我宁愿留下它。如果你能帮助我解决这个问题问题我会非常感激。

提前致谢！！

4

2 回答 2

1

请检查一下。

select 
(select P.FirstName  from Parent as P where P.ParentID = pl.FatherID ) as FatherName,
(select P.FirstName  from Parent as P where P.ParentID = pl.MotherID ) as MotherName,
pl.FirstName as PlayerFirstName, pl.LastName as PlayerLastName from player pl
于 2012-04-28T06:22:28.867 回答
1

对于您显示的确切输出，您希望按如下方式连接表：

SELECT
        parent.parentID  AS ParentID,
  ParentPerson.firstName AS ParentFirstName,
  ParentPerson.lastName  AS  ParentLastName,
   ChildPerson.firstName AS PlayerFirstName,
   ChildPerson.lastName  AS  PlayerLastName
FROM
       parent
  JOIN Player ON (parent.parentID IN (Player.motherID, Player.fatherID))
  JOIN person AS ParentPerson ON (ParentPerson.personID = parent.parentID)
  JOIN person AS  ChildPerson ON ( ChildPerson.personID = Player.playerID)
于 2012-04-28T08:20:10.103 回答