后续查询以下SQL：

Question

我有一个要编写为Sequelize查询的SQL查询。

SELECT users.username, players.points, tournaments.date
FROM USERS
JOIN players ON users.id = players.UserId
JOIN Tournaments ON tournaments.id = players.TournamentId
WHERE players.player_checkedin_flag = 1 AND users.role = "user";

我在玩家表中具有以下关联：

classMethods: {
    associate: function(models) {
      // Foreign key to user_id
      Player.belongsTo(models.User, {
        foreignKey: {
          allowNull: false
        }
      });
      // Foreign key to tournament_id
      Player.belongsTo(models.Tournament, {
        foreignKey: {
          allowNull: false
        }
      });

在“用户”表中，

{
  classMethods: {
    associate: function(models) {
      // User has many Player data
      User.hasMany(models.Player);
    }
  }
}

在锦标赛表中：

{
  classMethods: {
    associate: function(models) {
      // Tournament is connected to many player rows
      Tournament.hasMany(models.Player);
    }
  }
}

相应的续集查询是什么？

Answer 1

在这种情况下，您需要对这三个模型执行急切加载

User.all({
    attributes: ['username'], // return only 'username' column from 'users' table
    include: [
        {
            model: Player, // eager load players on players.userId = users.id
            attributes: ['points'], // return only 'points' column from 'players' table
            include: [{ model: Tournament, attributes: ['date'] }] // nested eager load of 'tournaments' table on tournaments.playerId = players.id
        }
    ],
    where: {
        playerCheckedinFlag: sequelize.where(sequelize.col('Player.player_checkedin_flag', '=', 1),
        role: 'user'
    },
    raw: true // used the raw attribute to prevent creating User instances from the query result due to the fact that we return 3 fields from 3 different tables
}).(result => {
    console.log(result);
});

sequelize在上面的代码是其中模型定义Sequelize的实例。 您还可以查看sequelize.where()方法的文档。