Question

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

Answer 1

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.