title: JOOQ pojos with one-to-many and many-to-many relations
body: <p>I am struggling to understand how to handle pojos with one-to-many and many-to-many relationships with JOOQ.</p>
  
  <p>I store locations that are created by players (one-to-many relation). A location can hold multiple additional players who may visit it (many-to-many). The database layout comes down to the following:</p>
  
  <pre class="lang-sql prettyprint-override"><code>CREATE TABLE IF NOT EXISTS `Player` (
    `player-id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
    `player` BINARY(16) NOT NULL,
    PRIMARY KEY (`player-id`),
    UNIQUE INDEX `U_player` (`player` ASC))
  ENGINE = InnoDB;
  
  CREATE TABLE IF NOT EXISTS `Location` (
    `location-id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
    `name` VARCHAR(32) CHARACTER SET 'utf8' COLLATE 'utf8_bin' NOT NULL,
    `player-id` INT UNSIGNED NOT NULL COMMENT '
    UNIQUE INDEX `U_name` (`name` ASC),
    PRIMARY KEY (`location-id`),
    INDEX `Location_Player_fk` (`player-id` ASC),
    CONSTRAINT `fk_location_players1`
      FOREIGN KEY (`player-id`)
      REFERENCES `Player` (`player-id`)
      ON DELETE NO ACTION
      ON UPDATE NO ACTION,
  ENGINE = InnoDB;
  
  CREATE TABLE IF NOT EXISTS `location2player` (
    `location-id` INT UNSIGNED NOT NULL,
    `player-id` INT UNSIGNED NOT NULL,
    INDEX `fk_ location2player_Location1_idx` (`location-id` ASC),
    INDEX `fk_location2player_Player1_idx` (`player-id` ASC),
    CONSTRAINT `fk_location2player_Location1`
      FOREIGN KEY (`location-id`)
      REFERENCES `Location` (`location-id`)
      ON DELETE NO ACTION
      ON UPDATE NO ACTION,
    CONSTRAINT `fk_location2player_Player1`
      FOREIGN KEY (`player-id`)
      REFERENCES `Player` (`player-id`)
      ON DELETE NO ACTION
      ON UPDATE NO ACTION)
  ENGINE = InnoDB;
  </code></pre>
  
  <p>Within my java application, all these informations are stored within one pojo. Note that the player and the list of invited players can be updated from within the application and need to be updated in the database as well:</p>
  
  <pre><code>public class Location {
  
      private final String name;
      private UUID player;
      private List&lt;UUID&gt; invitedPlayers;
  
      public void setPlayer(UUID player) {
          this.player = player;
      }
  
      public void invitePlayer(UUID player) {
          invitedPlayers.add(player);
      }
  
      public void uninvitePlayer(UUID player) {
          invitedPlayers.remove(player);
      }
  
      //additional methods…
  }
  </code></pre>
  
  <p>Can I use JOOQ’s pojo mapping to map these three records into the single pojo? Can I use JOOQ’s CRUD feature from this pojo to update the one-to-many and many-to-many relations? If the pojo mapping cannot be used, can I take advantage of JOOQ in any way except using it to write my SQL statements?</p>