c# - 如何在 C# 上更新和显示数据库结果

Question

我正在尝试使用 C# 进行一些考试并创建一个学生系统。我在表格行的可视化方面遇到了一些问题。

我创建了文本框，我应该在其中放置学生的成绩。我输入了值，但是当我再次启动应用程序时，这些字段为空。当我打开表时 - 值就在那里。此后的另一个问题是:如果文本框中有成绩，并且我想更改它，我不会在表中创建另一行，我想更新当前学生的行。表之间的通信是单元格“id”和“Faculty Number”。

程序:

CREATE PROCEDURE [dbo].InsertGrades
    @fakNum nvarchar(50),  
    @math int,
    @physic int,  
    @pik int,  
    @oip int,  
    @saa int,
    @ps int,  
    @pmu int,  
    @kp int,  
    @asls int,
    @pe int
AS
    INSERT INTO [Grades] (FakNumber, Math, Physic, PIK, OIP, SAA, PS, PMU, KP, ASLS, PE)
    VALUES (@fakNum , @math, @physic, @pik, @oip, @saa, @ps, @pmu, @kp, @asls, @pe)

bool 无效:

public static bool InsertGrades(Grade grd)
{
    GradesDataClassesDataContext grds = new GradesDataClassesDataContext();
    try
    {
        grds.InsertGrades(grd.FakNumber, grd.Math, grd.Physic, grd.PIK, grd.OIP, grd.SAA, grd.PS, grd.PMU, grd.KP, grd.ASLS, grd.PE);
        grds.SubmitChanges();
    }
    catch (Exception e)
    {
        System.Windows.Forms.MessageBox.Show(e.Message);
        return false;
    }
    return true;
}

另一个 bool 值:

public static bool InsertGrades(Grade g)
{
    if (g.Math > 6 && g.Math < 2 &&
        g.Physic > 6 && g.Physic < 2 &&
        g.PIK    > 6 && g.PIK    < 2 &&
        g.OIP    > 6 && g.OIP    < 2 &&
        g.SAA    > 6 && g.SAA    < 2 &&
        g.PS     > 6 && g.PS     < 2 &&
        g.PMU    > 6 && g.PMU    < 2 &&
        g.KP     > 6 && g.KP     < 2 &&
        g.ASLS   > 6 && g.ASLS   < 2 &&
        g.PE     > 6 && g.PE     < 2)

    {
        return UserData.InsertGrades(g);
    }
    else
    {
        return false;
    }
}

这必须将值从表格插入文本框，但事实并非如此:

private Data.Grade ReadStudentGrades()
{
    Data.Grade grd = new Data.Grade();
    grd.FakNumber = txtFakNumber.Text;
    grd.Math = Int32.Parse(txtMath.Text);
    grd.Physic = Int32.Parse(txtPhysic.Text);
    grd.PIK = Int32.Parse(txtPIK.Text);
    grd.OIP = Int32.Parse(txtOIP.Text);
    grd.SAA = Int32.Parse(txtSAA.Text);
    grd.PS = Int32.Parse(txtPS.Text);
    grd.PMU = Int32.Parse(txtPMU.Text);
    grd.KP = Int32.Parse(txtKP.Text);
    grd.ASLS = Int32.Parse(txtASLS.Text);
    grd.PE = Int32.Parse(txtPE.Text);
    grd.FakNumber = txtFakNumber.Text;

    return grd;
}

Answer 1

关于此代码:

This must insert values from table to textboxes, but it doesn't:

private Data.Grade ReadStudentGrades()
{
    Data.Grade grd = new Data.Grade();
    grd.FakNumber = txtFakNumber.Text;
    grd.Math = Int32.Parse(txtMath.Text);
    grd.Physic = Int32.Parse(txtPhysic.Text);
    grd.PIK = Int32.Parse(txtPIK.Text);
    grd.OIP = Int32.Parse(txtOIP.Text);
    grd.SAA = Int32.Parse(txtSAA.Text);
    grd.PS = Int32.Parse(txtPS.Text);
    grd.PMU = Int32.Parse(txtPMU.Text);
    grd.KP = Int32.Parse(txtKP.Text);
    grd.ASLS = Int32.Parse(txtASLS.Text);
    grd.PE = Int32.Parse(txtPE.Text);
    grd.FakNumber = txtFakNumber.Text;

    return grd;
}

此代码无法将值从表插入到文本框。这里没有一行为任何文本框分配值。

也许你把它搞反了？也许应该更像这样:

private Data.Grade ReadStudentGrades()
{
    Data.Grade grd = new Data.Grade();
    txtFakNumber.Text = grd.FakNumber;
    txtMath.Text = grd.Math.ToString();
    txtPhysic.Text = grd.Physic.ToString();
    txtPIK.Text = grd.PIK.ToString();
    (txtOIP.Text = grd.OIP.ToString();
    txtSAA.Text = grd.SAA.ToString();
    txtPS.Text = grd.PS.ToString();
    txtPMP.Text = grd.PMU.ToString();
    txtKP.Text = grd.KP.ToString();
    txtASLA.Text = grd.ASLS.ToString();
    txtPE.Text = grd.PE.ToString();
    txtFakNumber.Text = grd.FakNumber;

}