如何通过sequelize在where语句中使用db函数

Posted 2023-04-12

【中文标题】如何通过sequelize在where语句中使用db函数

【英文标题】：how to using a db function in where sentence via sequelize

【发布时间】：2018-05-28 03:41:24

【问题描述】：

我想求本周的平均值并按dayofweek分组，所以我写了这个sql，sql运行良好，但是如何通过sequelize达到同样的目的。

select dayofweek(datetime), avg(value) from Temperatures where week(datetime) = week(now()) group by dayofweek(datetime);

这是我的Temperatures 表： | field | type | |----------|-------------| | uuid | char(36) | | value | float | | datetime | datetime |

我看过sequelize的文档，但是where这句话后面好像没有明确说明如何使用函数，条件是函数而不是字段。

我已经试过了，但是不行

where: 
  [Sequelize.Op.eq]: [
    sequelize.fn('week', Temperature.sequelize.fn('now')),
    sequelize.fn('week', Temperature.sequelize.col('datetime')),
  ]
,

感谢您的帮助！

【参考方案1】：

您可以为此使用sequelize.fn，如下所示：

[sequelize.fn('dayofweek', sequelize.col('datetime')), 'datetime']

更多详情DO READ

【讨论】：

感谢您的帮助！where 是一个对象，我必须将它与 [Sequelize.Op.and] 运算符一起使用。

检查这个，你会得到更好的主意：***.com/questions/50553568/…

【参考方案2】：

最后，我发现下面的方法效果很好

return Temperature.findAll(
  attributes: [
    [Temperature.sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')), 'dayofweek'],
    [Temperature.sequelize.fn('AVG', Temperature.sequelize.col('value')), 'value'],
  ],
  where: sequelize.where(sequelize.fn('week', Temperature.sequelize.fn('now')), sequelize.fn('week', Temperature.sequelize.col('datetime'))),
  group: sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')),
);

如果我需要更多条件过滤器，只需添加一个 [Op.and] 运算符

return Temperature.findAll(
  attributes: [
    [Temperature.sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')), 'dayofweek'],
    [Temperature.sequelize.fn('AVG', Temperature.sequelize.col('value')), 'value'],
  ],
  where: 
    [Sequelize.Op.and]: [
      sequelize.where(sequelize.fn('week', Temperature.sequelize.fn('now')), sequelize.fn('week', Temperature.sequelize.col('datetime'))),
    ]
  ,
  group: sequelize.fn('dayofweek', Temperature.sequelize.col('datetime')),
);

这里是生成的sql

SELECT dayofweek(`datetime`) AS `dayofweek`, AVG(`value`) AS `value` FROM `Temperatures` AS `Temperature` WHERE (week(now())=week(`datetime`)) GROUP BY dayofweek(`datetime`);