How Do I Get My Linq Statement To Give Me Different Results Displayed

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I have a linq statement where i turned letter grades into numbers to calculate a gpa can anyone tell me why no matter what grade i click i get the same gpa of 68 for each one? maybe someone can look over my code and give me an answer or hint thanks

VB

Private Sub btnDisplay_Click(sender As Object, e As EventArgs) Handles btnDisplay.Click


        Dim dic As Dictionary(Of String, Integer) = New Dictionary(Of String, Integer)
        dic.Add("A", 4)
        dic.Add("B", 3)
        dic.Add("C", 2)
        dic.Add("D", 1)
        dic.Add("F", 0)

        Dim gpa = Aggregate Grade In CoursesDataSet.tblCourses.AsEnumerable()
           Select Grade.Field(Of Integer)("CreditHours") * dic(Grade.Field(Of String)("Grade"))
           Into Sum()


        MessageBox.Show("GPa:" & gpa.ToString("C2"),
                      "College Courses", MessageBoxButtons.OK,
MessageBoxIcon.Information)
    End Sub

End Class

this url is a pic of how the grades are shown on the database
http://i59.tinypic.com/2vinzeo.jpg[^]

Posted 6-May-15 7:42am

karodhill

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Comments

Sascha Lefèvre 6-May-15 14:41pm

What do you mean by "no matter what grade i click" ? There's nothing obvious to see in your code that gets influenced by some click. To me it looks like it's always operating with the same input data.

karodhill 6-May-15 14:54pm

Thats why i uploaded the picture the grades are already on the database with a button you click call gradedisplay the grades are displayed already on the form

Sascha Lefèvre 6-May-15 15:07pm

Yes I saw it. But I think you're leaving some info out. You say "no matter what grade you click" - but there's nothing to see in your code that depends on a "grade-click". What effect does/should a "grade-click" have?

karodhill 6-May-15 15:16pm

hmm I didnt think that would matter because there is a previous and nextbutton so i thought whatever its on as long as i say grade* hours it would compute now im really confused

Sascha Lefèvre 6-May-15 15:20pm

Just explain a bit more in detail how it *should* work :-)

karodhill 6-May-15 15:23pm

just basically when a user hits a next or previous button whatever grade is there should be multiplied by the credit hours to get the gpa now you have me thinking maybe i need a where clause or something but im to new to this language for the right syntax

Sascha Lefèvre 6-May-15 15:32pm

I think the solution by Maciej Los should be what you want :)
You threw me off with your wording "grade click" - you meant record click/selection right? No worries - but try to be very accurate in your explanation of a problem, it will increase your chances to get help :)

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Maciej Los · Answer 1 · 2015-05-06T09:23:00

Solution 1

All you need is Where[^] instruction inside query ;)

VB

Dim sID As String = "ValueFromDataGridViewCell" 'for example: CS100 
Dim gpa = Aggregate Grade In CoursesDataSet.tblCourses.AsEnumerable()
   Where Grade.Field(Of String)("ID").Contains(sId)
   Select Grade.Field(Of Integer)("CreditHours") * dic(Grade.Field(Of String)("Grade"))
   Into Sum()

Posted 6-May-15 9:23am

Maciej Los

Updated 6-May-15 9:24am

v2

Comments

Sascha Lefèvre 6-May-15 15:47pm

Pretty sure that's what he wants, so my 5!

Maciej Los 6-May-15 15:51pm

Thank you, Sascha ;)