如何为连接中的每个表获取不同的值

Question

我正在为活动预订网站建立一个数据库。现在我有与 (eventTickets, eventSponsors, eventGuests) TABLE 的一对多关系相关的 EVENTS 表。

CREATE TABLE EVENT (
           EVENT_ID INTEGER NOT NULL AUTO_INCREMENT,
           ORGANIZER_ID INTEGER NOT NULL,
          name VARCHAR(30) NOT NULL,
          picture VARCHAR(50) NULL,
          venue VARCHAR(50) NOT NULL,
         city VARCHAR(30) NOT NULL DEFAULT Ethiopia,
         sub_city VARCHAR(50) NULL,
         location VARCHAR(50) NOT NULL,
        category VARCHAR(50) NOT NULL,
        start_date DATE NOT NULL,
        end_date DATE NOT NULL,
        longitude DOUBLE NULL,
        latitude DOUBLE NULL,
        status VARCHAR(15) NOT NULL DEFAULT DRAFT,
        discription TEXT NOT NULL,
       country VARCHAR(30) NOT NULL DEFAULT Ethiopia,
        end_time TIME NOT NULL,
       start_time TIME NULL,
       created_on TIMESTAMP NOT NULL DEFAULT TIMESTAMP(),
       PRIMARY KEY (EVENT_ID),
      FOREIGN KEY (ORGANIZER_ID) REFERENCES organizer(ORGANIZER_ID) ON DELETE CASCADE ON UPDATE CASCADE

     ) ENGINE=INNODB;

     CREATE TABLE SPONSORS  (
           SPONSOR_ID INTEGER NOT NULL AUTO_INCREMENT,
            EVENT_ID INTEGER NOT NULL,
           name VARCHAR(50) NOT NULL,
          image VARCHAR(50) NULL,
          PRIMARY KEY (SPONSOR_ID),
    FOREIGN KEY (EVENT_ID) REFERENCES event(EVENT_ID) ON DELETE CASCADE ON UPDATE CASCADE

     ) ENGINE=INNODB;



        CREATE TABLE GUESTS (
          GUEST_ID INTEGER NOT NULL AUTO_INCREMENT,
         first_name VARCHAR(30) NOT NULL,
         last_name VARCHAR(30) NOT NULL,
        aka_name VARCHAR(50) NULL,
        title VARCHAR(15) NULL,
         bio VARCHAR(100) NULL,
        image VARCHAR(50) NULL,
        EVNT_ID INTEGER NOT NULL,
        PRIMARY KEY (GUEST_ID),
       FOREIGN KEY (EVENT_ID) REFERENCES event(EVENT_ID) ON DELETE CASCADE ON UPDATE CASCADE

     ) ENGINE=INNODB;

        CREATE TABLE EVENT_TICKETS (
            TICKET_ID INTEGER NOT NULL AUTO_INCREMENT,
            EVENT_ID INTEGER NOT NULL,
            name VARCHAR(20) NOT NULL,
            type VARCHAR(20) NOT NULL,
           price FLOAT(4) NOT NULL,
           quantity INTEGER NOT NULL,
          discription VARCHAR(255) NOT NULL,
          sale_start DATE NOT NULL,
          sale_end DATE NOT NULL,
        active BOOL NOT NULL DEFAULT 0,
        available INTEGER NOT NULL,
        created_on TIMESTAMP NOT NULL DEFAULT NOW(),
        PRIMARY KEY (TIK_ID)
        FOREIGN KEY (EVENT_ID) REFERENCES event(EVENT_ID) ON DELETE CASCADE ON UPDATE CASCADE

     ) ENGINE=INNODB;

现在我有了事件表

      EVENT_ID | NAME
        1      | firstEvent
        2      | secondEvent

赞助商表

  SPONSOR_ID | EVENT_ID | name
       1     |    1      |    firstEventSponsor
       2     |    2      |   secondEventSponsor   

客人桌

GUEST_ID | EVENT_ID | first_name  | last_name
   1     |     1    |  firstEvent | guest
   2     |     2    |  secondEvent| guest

和票表

TICKET_ID | EVENT_ID | type  
   1     |     1    |  free  
   2     |     2    |  secondEvent
   3     |     1    |  paid

如果记录存在，我想从其他每个表中获取具有特定事件的所有相关字段，如果没有记录，则为 NULL。当我进行连接时，我得到一个重复其他表记录的结果集，直到结果集表行计数的最大返回匹配

这是我的加入

   SELECT  `event`.`EVENT_ID` AS 'eventId' ,`event`.`name` AS 'eventName' , `venue` `TICKET_ID` AS 'ticketId', `eventTicket`.`type` AS 'ticketType',
      `eventGuest`.`GUEST_ID` AS 'guestId',  CONCAT(`eventGuest`.`first_name`, " ", `eventGuest`.`last_name`) AS 'guestName', 
        `eventSponsor`.`SPONSOR_ID` AS 'sponsorId', `eventSponsor`.`name` AS 'sponsorName', 
    FROM `event`

    LEFT OUTER JOIN `eventTicket` ON `event`.`EVENT_ID` = `eventTicket`.`EVENT_ID`
    LEFT JOIN `eventGuest` ON `eventTicket`.`EVENT_ID` = `eventGuest`.`EVENT_ID`
    LEFT JOIN `eventSponsor` ON  `eventGuest`.`EVENT_ID` = `eventSponsor`.`EVENT_ID`

    WHERE `event`.`EVENT_ID` = 1
    GROUP BY `event`.`EVENT_ID`, `eventTicket`.`TICKET_ID`, `eventGuest`.`GUEST_ID`, `eventSponsor`.`SPONSOR_ID`    ;

这样返回一个结果集

eventId | eventName    | ticketId | type | guestId | guestName      | sponsorId       | sponsorName
   1    | firstEvent   | 1        | free | 1       |firstEventGuest | 1 | firstEventSponsor
   1    | firstEvent   | 2        | paid | 1       |firstEventGuest | 1 | firstEventSponsor

如果可能的话，我希望获得类似这样的结果集

eventId | eventName    | ticketId | type | guestId | guestName      | sponsorId       | sponsorName
   1    | firstEvent   | 1        | free | 1       |firstEventGuest | 1 | firstEventSponsor
   1    | firstEvent   | 2        | paid | NULL       |NULL       | NULL  | NULL

我是我使用了错误的方法还是默认方法，请帮助我解决这个挑战/

Answer 1

这将适用于您的示例数据。

SELECT e.event_id AS 'eventId',
       e.name AS 'eventName',
       t.ticket_id AS 'ticketId',
       t.type AS 'ticketType',
       g.guest_id AS 'guestId',
       CONCAT(g.first_name, " ", g.last_name) AS 'guestName', 
       s.sponsor_id AS 'sponsorId',
       s.name AS 'sponsorName'
  FROM t_event e
  LEFT OUTER JOIN t_ticket t 
    ON e.event_id = t.event_id
  LEFT OUTER JOIN (SELECT *, CASE WHEN event_id = 1 THEN 1 ELSE event_id END ticket_id FROM t_guest) g 
    ON t.event_id = g.event_id AND t.ticket_id = g.ticket_id
  LEFT OUTER JOIN t_sponsor s 
    ON g.event_id = s.event_id
 WHERE e.event_id = 1
 GROUP BY e.event_id, t.ticket_id, g.guest_id, s.sponsor_id;

结果（我添加了 guest id 3 示例数据）

eventId eventName   ticketId ticketType  guestId guestName         sponsorId sponsorName
1       firstEvent  1        free        1       firstEvent guest  1         firstEventSponsor
1       firstEvent  1        free        3       thirdEvent guest  1         firstEventSponsor
1       firstEvent  3        paid        NULL    NULL              NULL      NULL
2       secondEvent 2        secondEvent 2       secondEvent guest 2         secondEventSponsor