如何将AND添加到联接SLICK [英] How to add AND to the join SLICK

问题描述

我在SLICK中编写查询时遇到问题 这是我对MySql数据库的请求:

I have the problem writing query in SLICK Here is my request to MySql database:

SELECT * FROM readings AS r
JOIN parameters AS p
LEFT JOIN sensorvalues AS sv ON sv.parameter_id=p.id AND sv.reading_id=r.id

如何使用SLICK编写它?确实缺少有关文档中联接的信息.

How can I write it using SLICK ? It is really lack of info on joins in docs.

更新1 我尝试了所有组合，甚至像这样

UPDATE 1 I tried all the combinations even one like this

val q = for{
  Join(p,sv) <- Parameters leftJoin SensorValues on (_.id is sv.parameter_id)
  r <- Readings if sv.reading_id is r.id
} yield(r,p,sv)

在这种情况下，编译器给我一个错误wrong number of parameters; expected = 2

In this case compiler gives me an error wrong number of parameters; expected = 2

所以我将sv.parameter_id替换为_.parameter_id，现在它讨论了Join 它说:

So I replaced sv.parameter_id to _.parameter_id and now it argues about Join It said that:

constructor cannot be instantiated to expected type; found : models.Join required: (models.Parameters.type, models.SensorValues.type)

我使用的是SLICK的最新版本，不建议使用.我手动导入

I'm using last version of SLICK and it's deprecated. I manually imported

import scala.slick.lifted.Join，现在看起来像是常规的innerJoin，因为它使用WHERE而不是放在ON后面并放在ON之后.

import scala.slick.lifted.Join and now it looks like it's regular innerJoin because it uses WHERE instead of putting and after ON.

SQL生成的购买查询:

SQL generated buy query:

select x2.id, x2.platform_id, x2.date, x3.x4, x3.x5, x3.x6, x7.x8, x7.x9, x7.x10, x7.x11 from (select x12.id as x4, x12.name as x5, x12.units as x6 from parameters x12) x3 left outer join (select x13.id as x8, x13.reading_id as x9, x13.parameter_id as x10, x13.value as x11 from sensorValues x13) x7 on x3.x4 = x7.x10, readings x2 where true and (x7.x9 = x2.id)

即使在打开"部分增加了条件，即使这样也很好

Even this one would be good with added condition to the ON section

 val readings = for {
        all <-Readings join Parameters leftJoin SensorValues on (_._2.id is _.parameter_id) if(all._1._1.id === all._2.reading_id)
      } yield (all._1._1,all._1._2,all._2)

但这永远不会发生.

SELECT
    x2.x3,
    x2.x4,
    x2.x5,
    x2.x6,
    x2.x7,
    x2.x8,
    x9.x10,
    x9.x11,
    x9.x12,
    x9.x13
FROM
    (
        SELECT
            x14.x15 AS x3,
            x14.x16 AS x4,
            x14.x17 AS x5,
            x18.x19 AS x6,
            x18.x20 AS x7,
            x18.x21 AS x8
        FROM
            (
                SELECT
                    x22.`id` AS x15,
                    x22.`platform_id` AS x16,
                    x22.`date` AS x17
                FROM
                    `readings` x22
            )x14
        INNER JOIN(
            SELECT
                x23.`id` AS x19,
                x23.`name` AS x20,
                x23.`units` AS x21
            FROM
                `parameters` x23
        )x18
    )x2
LEFT OUTER JOIN(
    SELECT
        x24.`id` AS x10,
        x24.`reading_id` AS x11,
        x24.`parameter_id` AS x12,
        x24.`value` AS x13
    FROM
        `sensorValues` x24
)x9 ON x2.x6 = x9.x12
WHERE
    x2.x3 = x9.x11

代替WHERE我需要AND.我应该用什么来提及这种情况，或者在此方面没有任何功能?

instead WHERE I need AND. What Should I use to mention this condition or there is no functionality in slick for that?

推荐答案

编辑
OP正在2个表对象的连接中查找按条件链接的.

EDIT
The OP is looking for chained on conditions in a join of 2 table objects.

应编译:

val q = for{
  r <- Readings
  Join(p,s) <- Params leftJoin Sensors on (
    (a,b)=> (a.id is b.parameter_id) && (b.reading_id is r.id)
  )
} yield(r,p,s)

原始
尝试这样的事情:

ORIGINAL
Try something like this:

val q = for{
  Join(p,s) <- Params leftJoin Sensors on (_.id is s.parameter_id)
  r <- Readings if s.reading_id is r.id
} yield(r,p,s)

val result = 
  q.list.map{ case(r,p,s)=>
    SomeCaseClass(r,p,s)
  }

这篇关于如何将AND添加到联接SLICK的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！