Question

我在VB.net中的If Ifse语句随机显示我所做的If或ElseIf条件。

我要做的是当选中DataGridView复选框并单击LinkLabel时，系统将获取所选的行，并将“EditTime”列更新为“ds”或“en”取决于列中已有的内容

因此，如果“EditTime”列中的数据设置为“ds”，则If Else条件应将其更改为“en”，反之亦然。

Dim en As OleDbCommand = New OleDbCommand("SELECT * FROM [Roster1]", myConnection)
        Dim d As OleDbDataReader = en.ExecuteReader
        Dim edt As String = ""
        While d.Read
            edt = d("EditTime").ToString
        End While


        Dim CheckedRows =
            (
                From Rows In AdminTabDisplay.Rows.Cast(Of DataGridViewRow)()
                Where CBool(Rows.Cells("ck").Value) = True
            ).ToList
        If CheckedRows.Count > 0 Then

        Dim sb As New System.Text.StringBuilder
        For Each row As DataGridViewRow In CheckedRows
            sb.AppendLine(row.Cells("Employee ID").Value.ToString)

        Next

            If edt = "ds" Then
                Dim st As String = sb.ToString
                Dim value As Integer = CInt(st)
                Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
                cmd.Parameters.AddWithValue("@pw", "en")
                cmd.Parameters.AddWithValue("@v", value)
                cmd.ExecuteNonQuery()
                MsgBox("Edit enabled!")

            ElseIf edt = "en" Then
                Dim st As String = sb.ToString
                Dim value As Integer = CInt(st)
                Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
                cmd.Parameters.AddWithValue("@pw", "ds")
                cmd.Parameters.AddWithValue("@v", value)
                cmd.ExecuteNonQuery()
                MsgBox("Edit disabled!")
            End If

这是我的代码。然而，输出似乎有点随机。

Answer 1

[Roster1]表中有多少行？因为有陈述：

    While d.Read
        edt = d("EditTime").ToString
    End While

在edt中，你总是拥有最后一行的值。是对的吗？

编辑：

试试这段代码：

    Dim CheckedRows =
        (
            From Rows In AdminTabDisplay.Rows.Cast(Of DataGridViewRow)()
            Where CBool(Rows.Cells("ck").Value) = True
        ).ToList
    If CheckedRows.Count > 0 Then

    For Each row As DataGridViewRow In CheckedRows

        Dim st as String = row.Cells("Employee ID").Value.ToString
        Dim value As Integer = CInt(st)

        Dim en As OleDbCommand = New OleDbCommand("SELECT * FROM [Roster1] WHERE [Employee ID] = @v", myConnection)
        cmd.Parameters.AddWithValue("@v", value)
        Dim d As OleDbDataReader = en.ExecuteReader
        Dim edt As String = d("EditTime").ToString

        If edt = "ds" Then
            Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
            cmd.Parameters.AddWithValue("@pw", "en")
            cmd.Parameters.AddWithValue("@v", value)
            cmd.ExecuteNonQuery()
            MsgBox("Edit enabled!")

        ElseIf edt = "en" Then
            Dim st As String = sb.ToString
            Dim value As Integer = CInt(st)
            Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
            cmd.Parameters.AddWithValue("@pw", "ds")
            cmd.Parameters.AddWithValue("@v", value)
            cmd.ExecuteNonQuery()
            MsgBox("Edit disabled!")
        End If
    Next

编辑（我在其中添加了WHILE循环并编辑了一些变量，它可以正常工作！）：</ p>

Dim CheckedRows =
    (
        From Rows In AdminTabDisplay.Rows.Cast(Of DataGridViewRow)()
        Where CBool(Rows.Cells("ck").Value) = True
    ).ToList
    If CheckedRows.Count > 0 Then


        For Each row As DataGridViewRow In CheckedRows

            Dim st As String = row.Cells("Employee ID").Value.ToString
            Dim value As Integer = CInt(st)

            Dim en As OleDbCommand = New OleDbCommand("SELECT * FROM [Roster1] WHERE [Employee ID] = @v", myConnection)
            en.Parameters.AddWithValue("@v", value)
            Dim d As OleDbDataReader = en.ExecuteReader
            Dim edt As String = ""

            While d.Read
                edt = d("EditTime").ToString
            End While

            If edt = "ds" Then
                Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
                cmd.Parameters.AddWithValue("@pw", "en")
                cmd.Parameters.AddWithValue("@v", value)
                cmd.ExecuteNonQuery()
                MsgBox("Edit enabled!")

            ElseIf edt = "en" Then
                Dim cmd As OleDbCommand = New OleDbCommand("UPDATE [Roster1] SET [EditTime] = @pw WHERE [Employee ID] = @v", myConnection)
                cmd.Parameters.AddWithValue("@pw", "ds")
                cmd.Parameters.AddWithValue("@v", value)
                cmd.ExecuteNonQuery()
                MsgBox("Edit disabled!")
            End If
        Next

    End If

Answer 2

不确定你是否有意这样做。对于如果edt =“ds”那么 en用于if块AddWithValue（“@ pw”，“ en ”）。对于 ElseIf edt =“en”然后，elseif块引用 cmd.Parameters.AddWithValue（“@ pw”，“ds”）

如果在VB.net中的Else语句结果是随机的

2 个答案: