左排除加入续集

我有两张表，其中一张表有另一张表的 ID。 1:1 关系。 所以像

EventFeedback
    somePrimaryKey
    userEventID
UserEvent
    userEventID

Sequelize 的关系定义为

models.UserEvent.hasOne(models.EventFeedback, { foreignKey: 'userEventID' });

I need all entries in UserEvent that do not have an entry in EventFeedback, which is an exclusionary join. Stealing images from this article https://www.codeproject.com/kb/database/visual_sql_joins.aspx because they have nice individual images:

他们甚至给出了示例代码！

SELECT <select_list> 
FROM Table_A A
LEFT JOIN Table_B B
ON A.Key = B.Key
WHERE B.Key IS NULL

我如何在续集中做到这一点？ 我只需要进行左连接并手动处理它吗？

你需要急切地加载EventFeedback查询时UserEvent并添加适当的where条款。您还需要定义EventFeedback结果中不需要，因此查询将生成LEFT JOIN反而INNER JOIN

UserEvent.findAll({
    include: [{
        model: EventFeedback,
        required: false, // do not generate INNER JOIN
        attributes: [] // do not return any columns of the EventFeedback table
    }],
    where: sequelize.where(
        sequelize.col('EventFeedback.userEventID'),
        'IS',
        null
    )
}).then(userEvents => {
    // user events...
});

在上面的代码中sequelize是 Sequelize 的一个实例，其中定义了模型。您还可以参考文档sequelize.where() http://docs.sequelizejs.com/en/latest/api/sequelize/#whereattr-comparator-logic-sequelizewhere and sequelize.col() http://docs.sequelizejs.com/en/latest/api/sequelize/#colcol-sequelizecol方法。