如何在没有额外查询的情况下删除续集中的关联？

Posted 2023-04-12

【中文标题】如何在没有额外查询的情况下删除续集中的关联？

【英文标题】：how to remove association in sequelize without extra query?

【发布时间】：2015-05-16 13:25:55

【问题描述】：

exercise 和 muscle 模型之间存在多对多关联。 我删除了单个关联

models.Exercise.find(where: id: exerciseId)
                .then(function(exercise)
                    exercise.removeMuscle(muscleId);
                    res.sendStatus(200);
                );

ORM 运行 3 个查询，其中 2 个是相似的

Executing (default): SELECT `Muscule`.`id`, `Muscule`.`title`, `Muscule`.`description`, `Muscule`.`video`, `Muscule`.`createdAt`,
    `Muscule`.`updatedAt`, `muscle_exercise`.`createdAt` AS `muscle_exercise.createdAt`, `muscle_exercise`.`updatedAt` AS `muscle_
    exercise.updatedAt`, `muscle_exercise`.`MusculeId` AS `muscle_exercise.MusculeId`, `muscle_exercise`.`ExerciseId` AS `muscle_exercise.ExerciseId` FROM `Muscules` AS `Muscule` INNER JOIN `muscle_exercise` AS `muscle_exercise` ON `Muscule`.`id` = `muscle_exercise`.`MusculeId` AND `muscle_exercise`.`ExerciseId` = 11;



 Executing (default): SELECT `Muscule`.`id`, `Muscule`.`title`, `Muscule`.`description`, `Muscule`.`video`, `Muscule`.`createdAt`,
    `Muscule`.`updatedAt`, `muscle_exercise`.`createdAt` AS `muscle_exercise.createdAt`, `muscle_exercise`.`updatedAt` AS `muscle_
    exercise.updatedAt`, `muscle_exercise`.`MusculeId` AS `muscle_exercise.MusculeId`, `muscle_exercise`.`ExerciseId` AS `muscle_exercise.ExerciseId` FROM `Muscules` AS `Muscule` INNER JOIN `muscle_exercise` AS `muscle_exercise` ON `Muscule`.`id` = `muscle_exercise`.`MusculeId` AND `muscle_exercise`.`ExerciseId` = 11;


    Executing (default): DELETE FROM `muscle_exercise` WHERE `ExerciseId` = 11 AND `MusculeId` IN (52)

有什么办法可以避免重复查询？如果我可以逃避第一个和第二个查询并只运行第三个真正有用的查询，那将是完美的吗？

【参考方案1】：

您可以像documentation using set function 那样传递关联对象的数组，而无需尝试删除该对象。但这基本上给你留下了三个查询。

为了在一个 DELETE 查询中实现它，您需要在代码中添加一个 tie 模型。在你的情况下，它看起来像这样：

models.Exercise = sequelize.define("exercise", 
   /* attributes */
);

models.Muscle = sequelize.define("muscle", 
   /* attributes */
);

models.exercise_muscle_tie = sequelize.define("exercise_muscle_tie", 
, 
    freezeTableName: true
);

models.Exercise.belongsToMany(models.Muscle,  as: 'muscles', foreignKey: 'exerciseId', through: models.exercise_muscle_tie );
models.Muscle.belongsToMany(models.Exercise,  as: 'exercises', foreignKey: 'muscleId', through: models.exercise_muscle_tie );

在您定义它并将其与 belongsToMany 关联到模型后，您的 删除脚本 将是：

models.exercise_muscle_tie.destroy( where:  exerciseId: 1856, muscleId: 57344  )

生成的 SQL：

Executing (default): 
DELETE FROM `exercise_muscle_tie` WHERE `exerciseId` = 1856 AND `muscleId` = 57344