I'm having an issue generating a cumulative sum by month in rails. This
is what I have:
@results = Student.connection.select_all("SELECT
x1.MonthNo
, x1.MonthName
, x1.Added
, SUM(x2.Added) AS RunningTotal
FROM
(
SELECT
MONTH(passed_on) AS MonthNo
, MONTHNAME(passed_on) AS MonthName
, COUNT(*) AS Added
FROM students
WHERE passed_on >= '2009-09-23'
GROUP BY MONTH(passed_on)
) AS x1
INNER JOIN (
SELECT
MONTH(passed_on) AS MonthNo
, MONTHNAME(passed_on) AS MonthName
, COUNT(*) AS Added
FROM students
WHERE passed_on >= '2009-09-23'
GROUP BY MONTH(passed_on)
) AS x2
ON x1.MonthNo >= x2.MonthNo
GROUP BY x1.MonthNo;")
@result = @results.map{ |result| result[:RunningTotal] }
@result returns this:
[nil, nil]
even though @results returns this:
[{"RunningTotal"=>"1", "MonthName"=>"February", "Added"=>"1",
"MonthNo"=>"2"}, {"RunningTotal"=>"11", "MonthName"=>"March",
"Added"=>"10", "MonthNo"=>"3"}]
I would like @result to return this:
[1,11]
Any suggestions thanks?
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