C＃代码用参数化的组合框过滤组合框

Question

I'm writing a program where I add a math-class to sql but use combo boxes for some of the foreign keys so that they can only choose from certain items in a reference table( for example the class names come from a different table with all the class names in. But for some reason the classnameid does not give correct id's when I use the combobox.selectedvalue function. it keeps on giving weird -14 and -25 as id's which is wrong. please help. here is my code

    private void btnAddClass_Click(object sender, EventArgs e)
    {
        int iclassroomID = Convert.ToInt16(cmbClassRoomName.SelectedValue);
        int iclassTypeID = Convert.ToInt16(cmbClassType.SelectedValue);
        int iHours = Convert.ToInt16(cmbHours.SelectedItem);
        int iMins = Convert.ToInt16(cmbMinutes.SelectedItem);
        string sClassLength = txtLength.Text;
        DateTime dtClassdate;
        dtClassdate = dateTimePicker1.Value;
        DateTime myClassDateandTime = dtClassdate.Date.AddHours(iHours).AddMinutes(iMins);
        txtOutput.Text = Convert.ToString(iclassroomID);



        int selectedyear = this.dateTimePicker1.Value.Year;
        int selectedmonth = this.dateTimePicker1.Value.Month;
        int selectedday = this.dateTimePicker1.Value.Day;


        int thisyear = Convert.ToInt16(DateTime.Now.Year);
        int thismonth = Convert.ToInt16(DateTime.Now.Month);
        int thisday = Convert.ToInt16(DateTime.Now.Day);


        if (cmbSchool.SelectedIndex == 0) 
        {
            MessageBox.Show("Please Select A School");
        }
        else if (cmbClassRoomName.SelectedIndex == 0)
        {
            MessageBox.Show("Please Select A Classroom");
        }
        else if (cmbClassType.SelectedIndex == 0)
        {
            MessageBox.Show("Please Select A Class Type");
        }
        else if (cmbHours.SelectedIndex == 0)
        {
            MessageBox.Show("Please Select the hour for the starting time of the class");
        }
        else if (cmbMinutes.SelectedIndex == 0)
        {
            MessageBox.Show("Please Select the minute for the starting time of the class");
        }
        else if (selectedyear < thisyear)
        {
            MessageBox.Show("Please Select a date forward from today");
        }
        else if (selectedmonth < thismonth)
        {
            MessageBox.Show("Please Select a date forward from today");
        }
        else if (selectedday < thisday)
        {
            MessageBox.Show("Please Select a date forward from today");
        }
        else if (txtLength.Text == "")
        {
            MessageBox.Show("Please enter the class length");
        }
        else
        {
            classTableAdapter.AddClass(iclassroomID, iclassTypeID, myClassDateandTime, sClassLength);
            this.Validate();
            this.classBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.geared4MathDataSet);
            MessageBox.Show("Class Added");
            this.Close();
        }
    }

    private void cmbSchool_SelectedIndexChanged(object sender, EventArgs e)
    {

        int iclassroomname = Convert.ToInt16(cmbSchool.SelectedValue);

        try
        {
            this.classRoomTableAdapter.FillBySchool(this.geared4MathDataSet.ClassRoom, iclassroomname);
            lblClassroomName.Visible = true;
            cmbClassRoomName.Visible = true;
        }
        catch (System.Exception ex)
        {
            System.Windows.Forms.MessageBox.Show(ex.Message);
        }

    }

http://imgur.com/FRl2Uew,0slWYAq there is my forms. there are 2 uploads on that link. click second page to see the second page

Answer 1

Can't see anything obvious that'll break.
Could you provide some sample inputs?
When you debug your code (where you get the -14,-25), are the objects the correct objects?

Code improvement suggestions:
Having said that, your variable names are ... lacking ... I can understand cmbClassRoomName , but all the iNames or dtNames don't need these prefixes. Also, if you do choose to use the type and the camel case, iclassTypeID should be iClassTypeID . Another issue is that the i prefix suggests it's an interface, not an int.

About your validation if/else block ... why is it there? Are you using WinForm/WPF/ASP? Have you considered using validations? it might be a bit funny the first time, but it's worth the time to learn in gold later on, decoupling your code so everything makes more sense.