Visual Basic 和 SQL 图片框控件

Question

使用叠加在图像上的图片框，如下所示。 Click for Form Layout

如果学生参加 class，当表格加载时，图片框会变成绿色勾号。如果学生不参加 class 则图片框变为空白。

使用 SQL 我可以查询数据库以 return 特定学生参加的所有 classes。这些 classes 存储在数组 StudentClass(n)

中

在数组 AttendsClass(n) 中存储了 50 个 class 时间表。全部具有默认值 False。如果学生参加 class，则数组中的特定参加 class 变为 True。

加载表单后，用户可以单击图片框以 select 使 class 和数组中相应的 attendsclass 变为真。最后，用户保存表单，将 classes 重新插入数据库。

我遇到的问题是在 Sub Form4_Load 最后，我目前必须重复相同的代码块 50 次。这只是检查学生是否参加 class，然后将图片框 = 设置为 GUI (_new.jpg) 上的勾号图像。

enter code here
If AttendsClass(1) = True Then
        PictureBox1.Image = My.Resources._new
    End If
    If AttendsClass(2) = True Then
        PictureBox2.Image = My.Resources._new
    End If
    If AttendsClass(3) = True Then
        PictureBox3.Image = My.Resources._new
    End If
    If AttendsClass(4) = True Then
        PictureBox4.Image = My.Resources._new
    End If

是否可以将其放入循环中以缩短我的代码。该代码确实有效，但速度缓慢且冗长，因此任何改进都会有所帮助。非常感谢 Alex Currie A Level 计算学生完整代码：

enter code here
Imports System.Data.OleDb
Public Class Form4
Public con As New OleDbConnection
Public ds As New DataSet
Public da As OleDbDataAdapter
Public cb As OleDbCommandBuilder
Public constring As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source    =" & Application.StartupPath & "\wma.accdb"
Public AttendsClass(50) As Boolean
Public StdID As Integer = Form2.DataGridView1.SelectedRows(0).Cells("StudentID").Value
Private Sub Form4_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim Forename As String = Form2.DataGridView1.SelectedRows(0).Cells("Forename").Value
    Dim Surname As String = Form2.DataGridView1.SelectedRows(0).Cells("Surname").Value
    Student.Text = "Student: " & Forename & " " & Surname
    If Not con.State = ConnectionState.Open Then
        con.ConnectionString = constring
        con.Open()
    End If
    da = New OleDbDataAdapter("SELECT * FROM StudentClass WHERE StudentId = " & StdID, con)
    da.Fill(ds, "Class")
    Dim Maxrow As Integer = ds.Tables("Class").Rows.Count
    Dim StudentClass(Maxrow) As Integer
    For n = 1 To 50
        AttendsClass(n) = False
    Next

    For n = 1 To Maxrow
        StudentClass(n) = ds.Tables("Class").Rows(n - 1).Item(1)
        For a = 0 To 50
            If StudentClass(n) = a Then
                AttendsClass(a) = True
            End If
        Next
    Next

    If AttendsClass(1) = True Then
        PictureBox1.Image = My.Resources._new
    End If
    If AttendsClass(2) = True Then
        PictureBox2.Image = My.Resources._new
    End If
    If AttendsClass(3) = True Then
        PictureBox3.Image = My.Resources._new
    End If
    If AttendsClass(4) = True Then
        PictureBox4.Image = My.Resources._new
    End If

End Sub

Private Sub PictureBox1_Click(sender As System.Object, e As System.EventArgs) Handles PictureBox1.Click
    If PictureBox1.Image Is Nothing Then
        PictureBox1.Image = My.Resources._new
        AttendsClass(1) = True
    Else
        PictureBox1.Image = Nothing
        AttendsClass(1) = False
    End If
End Sub

Private Sub PictureBox2_Click(sender As System.Object, e As System.EventArgs) Handles PictureBox2.Click
    If PictureBox2.Image Is Nothing Then
        PictureBox2.Image = My.Resources._new
        AttendsClass(2) = True
    Else
        PictureBox2.Image = Nothing
        AttendsClass(2) = False
    End If
End Sub

Private Sub PictureBox4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox4.Click
    If PictureBox4.Image Is Nothing Then
        PictureBox4.Image = My.Resources._new
        AttendsClass(4) = True
    Else
        PictureBox4.Image = Nothing
        AttendsClass(4) = False
    End If
End Sub

Private Sub PictureBox3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox3.Click
    If PictureBox3.Image Is Nothing Then
        PictureBox3.Image = My.Resources._new
        AttendsClass(3) = True
    Else
        PictureBox3.Image = Nothing
        AttendsClass(3) = False
    End If
End Sub

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
    If Not con.State = ConnectionState.Open Then
        con.ConnectionString = constring
        con.Open()
    End If
    Dim cmd As New OleDb.OleDbCommand
    cmd.Connection = con

    'Deletes Existing Records To Be rewritten'
    cmd.CommandText = "DELETE * FROM StudentClass WHERE StudentID=" & StdID
    cmd.ExecuteNonQuery()

    For n = 1 To 50
        If AttendsClass(n) = True Then
            cmd.CommandText = "INSERT INTO StudentClass (StudentID, ClassID) VALUES (" & StdID & "," & n & ")"
            cmd.ExecuteNonQuery()
        End If
    Next
    Me.Dispose()
    MsgBox("Updated Successfully", MsgBoxStyle.Information, "WMA")
    con.Close()
End Sub
End Class

Answer 1

工作示例：

Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
 Handles PictureBox1.Click, ...., PictureBox50.Click
    Dim pic As PictureBox = CType(Controls(CType(sender, PictureBox).Name), PictureBox)
    'now you have clicked picturebox
    'you can change image by pic.Image = ...
    'if you want picturebox index, use line below:
    Dim picidx As Integer = CInt(CType(sender, PictureBox).Name.Replace("PictureBox", ""))

End Sub

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