VB.net数据绑定

Question

嘿，这是一项家庭作业，我无法弄清楚。 任何帮助将是巨大的！

创建一个具有下表的名为“ people”的SQL Server数据库。 请使用Visual Studio 2012并创建一个基于本地服务的数据库

people_id int PK身份名varchar（30）姓varchar（40）

创建一个Windows窗体程序，该程序在datagridview中列出ID，名字和姓氏

提供功能（在使用命令对象和参数的代码中，没有向导）来添加，更新和删除数据库表，并在datagridview中反映更改。

这是我已经拥有的代码。 我可以运行我的程序，数据将显示在datagridview中，但是每当我去添加更新或删除数据时，都不会发生任何事情。 我没有抛出任何错误。 我不知道如何解决这个问题，请帮忙！

Imports System.Data
Imports System.Data.SqlClient

Public Class Form1

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    DataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect
    Me.PeopleTableAdapter.Fill(Me.PeopleDataSet.people)
End Sub

Private Function getConnString() As String
    Return My.Settings.PeopleConnectionString.ToString()
End Function

Private Sub ExitToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExitToolStripMenuItem.Click
    Me.Close()
End Sub

Private Function getConnection() As String
    Return My.Settings.PeopleConnectionString.ToString()
End Function

Private Function getPeople(lName As String) As DataTable
    Dim sql As String
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    Dim da As SqlDataAdapter
    Dim dt As New DataTable
    Dim plName As New SqlParameter
    plName.ParameterName = "@lName"
    plName.Value = lName
    sql = "select * from people where lName = @lName"
    conn = New SqlConnection(getConnection())
    conn.Open()
    cmd = New SqlCommand(sql, conn)
    cmd.Parameters.Add(plName)
    da = New SqlDataAdapter(cmd)
    da.Fill(dt)
    conn.Close()
    Return dt
End Function

Private Sub AddPerson(fname As String, lname As String, person_ID As Integer)
    Dim sql As String
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    sql = "insert into people(fName, lName, person_ID) values("
    sql += "@fName, @lName, @person_ID)"
    conn = New SqlConnection(getConnection())
    conn.Open()
    cmd = New SqlCommand(sql, conn)
    cmd.Parameters.AddWithValue("@fName", fname)
    cmd.Parameters.AddWithValue("@lName", lname)
    cmd.Parameters.AddWithValue("@person_ID", person_ID)
    cmd.ExecuteNonQuery()
    conn.Close()
End Sub

Private Sub btnADD_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
    Try
        AddPerson(txtfName.Text, txtlName.Text, txtpID.Text)
        MessageBox.Show("Added")
    Catch ex As Exception
        MessageBox.Show("Error" & ex.Message)
    End Try
End Sub

Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
    If DataGridView1.SelectedRows.Count > 0 Then
        Dim dr As DataGridViewRow = DataGridView1.SelectedRows(0)
        txtfName.Text = dr.Cells(1).Value.ToString()
        txtlName.Text = dr.Cells(2).Value.ToString()
        txtpID.Text = dr.Cells(0).Value.ToString()
    End If
End Sub

Private Sub btnUpdate_Click(sender As Object, e As EventArgs) Handles btnUpdate.Click
    Dim sql As String
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    sql = "update people set fName=@fName, lName=@lName"
    sql += " where person_ID=@person_ID"
    conn = New SqlConnection(getConnection())
    conn.Open()
    cmd = New SqlCommand(sql, conn)
    cmd.Parameters.AddWithValue("@fName", txtfName.Text)
    cmd.Parameters.AddWithValue("@lName", txtlName.Text)
    cmd.Parameters.AddWithValue("@person_ID", txtpID.Text)
    cmd.ExecuteNonQuery()
    conn.Close()
End Sub

Private Sub btnView_Click(sender As Object, e As EventArgs) Handles btnView.Click
    Dim sql As String
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    sql = "delete from people where person_ID=@person_ID"
    conn = New SqlConnection(getConnection())
    conn.Open()
    cmd = New SqlCommand(sql, conn)
    cmd.Parameters.AddWithValue("@person_ID", txtpID.Text)
    cmd.ExecuteNonQuery()
    conn.Close()

End Sub
End Class

Answer 1

对不起，我没有50个声誉。

对于任何连接，您都无法预测数据库是否正在运行，因此您必须键入try catch并向用户/支持人员返回一条消息，以使他们知道此问题的发生，对于vb中的异常类型，请检查以下内容： Visual Basic .NET中的异常处理简介

请使用

try{
    ' your action, connection or sql exe
    ' example using your update event
    Dim sql As String
    Dim conn As SqlConnection
    Dim cmd As SqlCommand
    sql = "update people set fName=@fName, lName=@lName"
    sql += " where person_ID=@person_ID"
    conn = New SqlConnection(getConnection())
    conn.Open()
    cmd = New SqlCommand(sql, conn)
    cmd.Parameters.AddWithValue("@fName", txtfName.Text)
    cmd.Parameters.AddWithValue("@lName", txtlName.Text)
    cmd.Parameters.AddWithValue("@person_ID", txtpID.Text)
    cmd.ExecuteNonQuery()
    conn.Close()
}catch(Exception e){
    ' print the error message from here to let u know the function/ event error or not
    ' check the exception message
    ' MsgBox(e.ToString())
    conn.Close()
} finally {
    conn.Close()
}

检查按钮事件是否错误。

我也一直在用

MsgBox("Alert") 

帮助我检查功能或事件是否已运行。

希望对您有所帮助。

还有一件事...请以类的形式键入连接，因此您不必多次键入。