Question

我试图在MySQL数据库中更新和插入记录，我可以在单独的按钮中执行这两项操作，但我想从一个按钮执行两个查询。我想做的事情如下：如果ID（主键）=那么更新，否则插入，但我无法弄清楚我可以做什么。我会在下面提供一些代码。

INSERTING

Private Function saveCustomer()
    Dim command As MySqlCommand = Nothing
    Dim query As String = "INSERT INTO contacts (first_name, surname, house_number, street, suburb, state, phone, mobile, work, email, notes) VALUES (@first_name, @surname, @housenumber, @street, @suburb, @state, @phone, @mobile, @work, @email, @notes)"
    Try
        If connection.State = ConnectionState.Closed Then
            connection.Open()

        End If
        command = New MySqlCommand(query, connection)
        command.Parameters.AddWithValue("@first_name", txtFirstName.Text)
        command.Parameters.AddWithValue("@surname", txtSurname.Text)
        command.Parameters.AddWithValue("@housenumber", txtHouseNo.Text)
        command.Parameters.AddWithValue("@street", txtStreet.Text)
        command.Parameters.AddWithValue("@suburb", txtSuburb.Text)
        command.Parameters.AddWithValue("@state", cboState.Text)
        command.Parameters.AddWithValue("@phone", txtPhone.Text)
        command.Parameters.AddWithValue("@mobile", txtMobile.Text)
        command.Parameters.AddWithValue("@work", txtWork.Text)
        command.Parameters.AddWithValue("@email", txtEmail.Text)
        command.Parameters.AddWithValue("@notes", txtNotes.Text)
        command.ExecuteNonQuery()
        MessageBox.Show("Contact Saved Sucessfully")
        Return True
    Catch ex As MySqlException
        Return False
    Finally
        connection.Close()
        command.Dispose()
    End Try

End Function

UPDATING

Private Sub updateContact()
    Dim command As MySqlCommand = Nothing
    Dim query As String = "UPDATE contacts SET first_name=@first_name, surname=@surname, house_number=@housenumber, street=@street, suburb=@suburb, state=@state, phone=@phone, mobile=@mobile, work=@work, email=@email, notes=@notes WHERE id= '" & ListView1.FocusedItem.SubItems(1).Text & "'"

    Try
        connection.Open()

        command = New MySqlCommand(query, connection)
        command.Parameters.AddWithValue("@first_name", txtFirstName.Text)
        command.Parameters.AddWithValue("@surname", txtSurname.Text)
        command.Parameters.AddWithValue("@housenumber", txtHouseNo.Text)
        command.Parameters.AddWithValue("@street", txtStreet.Text)
        command.Parameters.AddWithValue("@suburb", txtSuburb.Text)
        command.Parameters.AddWithValue("@state", cboState.Text)
        command.Parameters.AddWithValue("@phone", txtPhone.Text)
        command.Parameters.AddWithValue("@mobile", txtMobile.Text)
        command.Parameters.AddWithValue("@work", txtWork.Text)
        command.Parameters.AddWithValue("@email", txtEmail.Text)
        command.Parameters.AddWithValue("@notes", txtNotes.Text)
        command.ExecuteNonQuery()

        MessageBox.Show("Contact Updated Successfully")

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        connection.Close()
        command.Dispose()

    End Try
End Sub

而这是我从数据库中获取的信息

Private Sub loadcontacts() 
    Dim command As MySqlCommand = Nothing
    Dim listquery As String = "SELECT * FROM contacts ORDER BY id"
    Dim reader As MySqlDataReader = Nothing

    Try
        If connection.State = ConnectionState.Closed Then
            connection.Open()
        End If

        command = New MySqlCommand(listquery, connection)
        reader = command.ExecuteReader()
        command.CommandText = listquery

        With ListView1
            .Columns.Add("Name", 220, HorizontalAlignment.Left)

        End With


        While reader.Read
            Dim ls As New ListViewItem(reader.Item("first_name").ToString() & " " & reader.Item("surname").ToString)
            ls.SubItems.Add(reader.Item("id").ToString)
            ListView1.Items.Add(ls)

        End While

    Catch ex As MySqlException
    Finally
        connection.Close()
        command.Dispose()
    End Try

End Sub

更新

我仍然无法解决问题，我通过包含一个文本框并让它读取ID来作弊，然后我告诉它保存，如果它是空的。我更愿意这样做，所以如果有人能说话，我会很感激。

Answer 1

自从我使用VB以来已经很久了，所以我确信语法有点过时了。任何人都可以根据需要自由编辑。

在按钮单击事件处理程序

中

If LEN(ListView1.FocusedItem.SubItems(1).Text) > 0 Then
    updateContact()
Else
    saveCustomer()
End If

注意我假设ID在

中设置

ListView1.FocusedItem.SubItems(1).Text

并且，如果正在编辑的记录是新的，则将评估为空字符串。如果这个假设是错误的，那么您必须分享如何知道ID是否可用于插入/更新。

<强>更新

如果我在尝试创建新记录之前没有选择记录，那么它会崩溃

在这种情况下，而不是检查

ListView1.FocusedItem.SubItems(1).Text

你应该检查ListView1是否有任何重点项目。

If ListView1.FocusedItem <> NULL Then
    updateContact()
Else
    saveCustomer()
End If

使用vb.net在一个按钮中更新和插入mysql记录

1 个答案: