Question

我正在为活动预订网站建立一个数据库。现在我的EVENTS表与（eventTickets，eventSponsors，eventGuests）TABLE的一对多关系有关。

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

嘉宾表

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

和票证表

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

如果记录存在，我想从每个其他表中获取所有相关字段，如果没有，则返回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`    ;

这会返回一个像这样的结果集

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

正在重复事件发生人和事件赞助商记录的行列我想要得到一个看起来像这样的结果如果它可能

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

我使用的是错误的方法，或者是默认的，请帮助我坚持这个挑战/

Answer 1

这将适用于您的样本数据。

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（我已添加访客ID 3样本数据）

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

如何为连接中的每个表获取不同的值

1 个答案: