使用MS SQL作为数据库的VB.net程序。 然后，当我尝试向表中插入另一个值时弹出此错误

Question

Imports System.Data.Sql
Imports System.Data.SqlClient

Public Class Main
    Dim c As New SqlCommand
    Dim connection As String = "Server=DESKTOP-7MC233A\SQLJOSE;database=AttendanceLog;user id=sa;password=pogi1234;"

    Private Sub Main_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Timer1.Enabled = True

        Dim dtmNow As DateTime = System.DateTime.Now

        If dtmNow.Hour > 0 And dtmNow.Hour < 11 Then
            Label2.Text = "Good morning"

        ElseIf dtmNow.Hour > 12 And dtmNow.Hour < 18 Then
            Label2.Text = "Good afternoon"

        ElseIf dtmNow.Hour > 19 And dtmNow.Hour < 23 Then
            Label2.Text = "Good evening "
        Else

        End If
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        lblDate.Text = Date.Now.ToString("MMM dd,yyyy")
        lblTime.Text = Date.Now.ToString("hh:mm:ss")
    End Sub

    Private Sub Label1_Click(sender As Object, e As EventArgs) Handles lblDate.Click

    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbNames.SelectedIndexChanged



    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Using con As New SqlConnection(connection)
            Try
                If con.State = ConnectionState.Closed Then
                    con.Open()
                End If

                With c
                    .Connection = con
                    .CommandText = "Insert into TimeIn values(@Name,@TimeIn,@Date)"
                    .CommandType = CommandType.Text

                    .Parameters.AddWithValue("@Name", cmbNames.Text)
                    .Parameters.AddWithValue("@TimeIn", lblTime.Text)
                    .Parameters.AddWithValue("@Date", lblDate.Text)

                    .ExecuteNonQuery()

                End With
                Dim dtmNow As DateTime = System.DateTime.Now

                If dtmNow.Hour > 9 Then
                    MsgBox("You are late!!!", MsgBoxStyle.Critical)
                ElseIf dtmNow.Hour < 9 Then

                    MsgBox("You are on time!", MsgBoxStyle.Information)

                End If



            Catch ex As Exception
                MsgBox("From: " & ex.Message)
            End Try
            con.Dispose()

        End Using

    End Sub
End Class

Here are my codes, and I'm very lost to what I'm going to do next. Thanks in advance for the help.

Answer 1

Just Dispose you sqlCommand every after using it.
you can use:

Using c As New SqlCommand("commandtext", connection")

Or you can just..

With c
'after the execution
.Parameters.Clear()
.Dispose
End With

Answer 2

Create a new sqlcommand every time. The same way you create a new Connection every time.

The problem you have is that you're adding @name again on the second pass.

Using con As New SqlConnection(connection) 
    Using cmd as New SqlCommand(...)

    ....

    End Using
End Using