在Google bigquery中加入3个表格 [英] Joining 3 tables in Google bigquery

问题描述

下面的示例停止在第一行的JOIN处添加一条错误消息在第13行第4列遇到JOINJOIN b
$ b

）

我在Bigquery中多次连接时丢失了什么明显的东西？

  SELECT type.CourseType AS CourseType，
 SUM（joined.assign.StudentCount）AS StudentN 
 FROM 
（
 SELECT assign.StateCourseCode，
 assign.StateCourseName， 
 assign.MatchType，
 assign.Term，
 assign.StudentCount 
 
 FROM [Assignment.AssignmentExtract5] AS赋值
 
 JOIN SELECT wgt .Term，
 wgt.Weight 
 
 FROM [Crosswalk.TermWeights] AS wgt 
 ON wgt.Term = assign.Term 
 
）加入
 
 JOIN SELECT type.CourseCode，
 type.CourseDescription，
 type.CourseType，
 type.CourseCategory 
 
从[Crosswalk.CourseTypeDescription] AS类型
 ON joined.assign.StateCourseCode = type.CourseCode 
 
 GROUP BY CourseType 
  

<我认为你只是错过了第13行的括号。

这个：

  JOIN SELECT wgt.Term，
 wgt.Weight 
 
 FROM [Crosswalk.TermWeights] AS wgt 
 ON wgt.Term = assign.Term 
  

应该是：

  JOIN（SELECT wgt.Term，
 wgt.Weight 
 
 FROM [Crosswalk.TermWeights]）由于$ b $ $ b ON wgt.Term = assign.Term 
  

更多信息：
https://developers.google.com/bigquery/docs/query-reference#multiplejoinsexample

仅供参考 - JOIN的速度并不像我们想要的那么快。我们正在努力提高性能。

The example below stops at the first JOIN with an error message

Encountered " "JOIN" "JOIN "" at line 13, column 4. Was expecting: ")"

Am I missing something obvious with multiple joins in Bigquery?

SELECT type.CourseType AS CourseType, 
       SUM(joined.assign.StudentCount) AS StudentN
FROM
  (
   SELECT assign.StateCourseCode,
          assign.StateCourseName,
          assign.MatchType, 
          assign.Term, 
          assign.StudentCount

   FROM [Assignment.AssignmentExtract5] AS assign

   JOIN SELECT wgt.Term,
               wgt.Weight 

    FROM [Crosswalk.TermWeights] AS wgt
     ON wgt.Term = assign.Term

 ) AS joined

JOIN SELECT type.CourseCode,
            type.CourseDescription, 
            type.CourseType, 
            type.CourseCategory 

FROM [Crosswalk.CourseTypeDescription] AS type
  ON joined.assign.StateCourseCode = type.CourseCode

GROUP BY CourseType

解决方案

I think you're just missing a parenthesis on line 13.

This:

   JOIN SELECT wgt.Term,
               wgt.Weight 

    FROM [Crosswalk.TermWeights] AS wgt
     ON wgt.Term = assign.Term

Should be:

   JOIN (SELECT wgt.Term,
               wgt.Weight 

    FROM [Crosswalk.TermWeights]) AS wgt
     ON wgt.Term = assign.Term

More info: https://developers.google.com/bigquery/docs/query-reference#multiplejoinsexample

FYI - JOINs are not as fast as we'd like yet. We're working on improving the performance.

这篇关于在Google bigquery中加入3个表格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！