Question

嘿伙计我遇到问题对象引用没有设置为对象的实例。我是一个完整的初学者，所以任何说明/解决方案将不胜感激。

导入System.Data.SqlClient 导入MySql.Data.MySqlClient

Public Class Form1



Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)      Handles MyBase.Load
    Dim connectionstring As String
    Dim commandtext As String
    Dim da As MySqlDataAdapter
    Dim table As DataTable
    commandtext = "select * From student"
    connectionstring = "Server=*****;Database=Harry;Uid=****;Pwd=****;Allow Zero Datetime=True;"


    Try
        da = New MySqlDataAdapter(commandtext, connectionstring)
        table = New DataTable
        da.Fill(table)
        DataGridView1.DataSource = table

    Catch ex As Exception
        MsgBox(ex.ToString)



    End Try
    Dim ds As New DataSet
    da = New MySqlDataAdapter
    da.Fill(ds, "student")


    DataGridView1.DataSource = ds.Tables("student")


End Sub


Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    ds.Tables("student").DefaultView.RowFilter = "student_id LIKE '%" & TextBox1.Text & "%' OR name LIKE '%" & TextBox1.Text & "*'"

End Sub

结束班

Answer 1

在我看来，你的问题就是ds的声明。

当您打算在不止一个地方使用它时，请尝试将其声明为全局变量。我没有看到你声明它的方式有什么问题，简单地在你的类中放置'Dim ds As New DataSet'但在load事件之上。

动态过滤Datagridview VB

1 个答案: