我正在尝试计算特定学生“UG10001”在特定月份从mysql数据库中的离开表中获取的离开。我正在使用以下代码片段 -
def calculate(student_id)
leave = Leave.find_by_sql("SELECT leave_duration FROM leaves WHERE MONTH(leave_from) = 2
AND YEAR(leave_from) = 2013 AND MONTH(leave_to) = 2 AND YEAR(leave_to) = 2013 AND
academic_status = 'APPROVED' AND warden_status = 'APPROVED' AND student_id = student_id
AND status = 'ACTIVE'")
sum = leave.sum(&:leave_duration)
return sum
end
---------- ----------更新
def calculate(student_id)
sum = Leave.find_by_sql("SELECT leave_duration FROM leaves WHERE MONTH(leave_from) = 2
AND YEAR(leave_from) = 2013 AND MONTH(leave_to) = 2 AND YEAR(leave_to) = 2013 AND
academic_status = 'APPROVED' AND warden_status = 'APPROVED' AND student_id = student_id
AND status = 'ACTIVE'").sum(&:leave_duration)
return sum
#it did the trick for me.
end
上述方法将计算特定学生在2013年2月份的假期，并将叶子总和返回给调用函数。
def calcuateLeaveForEachStudent
array = Leave.find_by_sql("select student_id from students")
c = Array.new
for i in 0...array.length
student_id = array[i].student_id
c[i] = calculate(student_id)
end
end
但是当我调用上面的方法时，'calculate'方法在每次迭代时返回相同的值。这可能是什么解决方案..？在此先感谢..！
PS -
代码在Rails控制台上运行完美，没有任何语法错误，但是有一些我无法弄清楚的错误。