datagridview不会使用combobox vb.net清除数据

Question

当我从组合框中选择项目时，我让项目有组合框项目它是来自同一个表格中不同列的数据视图中的视图数据 问题是当我从组合框数据网格查看数据中选择项目时，当我选择其他项目形式组合框数据网格视图新列与旧列

这是我的代码：

Dim sqlconn As New SqlConnection(con) 
Dim comm As New SqlCommand 
'Dim comm2 As New SqlCommand
Dim sql As String = "select * from entsab"
Dim adpt As New SqlDataAdapter(Sql, con)
Dim ds As New DataSet()
Dim dr As SqlDataReader 
Dim dr2 As SqlDataReader
Dim dt As New DataTable
Private Sub ComboBox2_SelectedValueChanged(sender As Object, e As EventArgs) Handles ComboBox2.SelectedValueChanged, ComboBox3.SelectedValueChanged
    Select Case ComboBox2.SelectedItem
        Case ComboBox2.Items.Item(0) '1
            dt.Clear()
            Dim comm2 As New SqlCommand
            comm2.CommandText = Nothing
            DGV1.Refresh()
            comm2.CommandText = "select l1,sub_code,sub_name,houres from sub_with_sct where sction_ID=1"
            comm2.Connection = sqlconn
            sqlconn.Open()
            dr2 = comm2.ExecuteReader
            dt.Load(dr2)
            DGV1.AutoGenerateColumns = True
            DGV1.DataSource = dt
            DGV1.Refresh()
            sqlconn.Close()
            DGV1.Visible = True
            comm2.Dispose()
        Case ComboBox2.Items.Item(1)
            dt.Clear()
            Dim comm2 As New SqlCommand
            DGV1.DataSource = Nothing
            DGV1.Columns.Clear()
            comm2.CommandText = Nothing
            DGV1.Refresh()
            comm2.CommandText = "select l2,sub_code,sub_name,houres from sub_with_sct where sction_ID=1"
            comm2.Connection = sqlconn
            sqlconn.Open()
            dr2 = comm2.ExecuteReader
            dt.Load(dr2)
            DGV1.AutoGenerateColumns = True
            DGV1.DataSource = dt
            DGV1.Refresh()
            sqlconn.Close()
            DGV1.Visible = True
            comm2.Dispose()
    End Select
End Sub

当我选择第一项时：

当我选择第二项时：

Answer 1

尝试将rvm rubygems 1.8.7 --force 添加到您的第一个 案件 。在你的所有案件中使用DGV1.Columns.Clear()代替dt= New DataTable()。