出现"未处理的“System.NullReferenceException”类型的异常出现在...."的问题

[liach]

代码如下:

Public Class Form1
Inherits System.Windows.Forms.Form
Private index As Int16 = -1
Private dt As DataTable
Private sqlcon As New SqlConnection("data source=liach;database=samples;user id=sa;pwd=lenovo2006")

Private Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim flag As Boolean = True
If Me.ID.Text.Trim() = "" Then
MessageBox.Show("请先选中要修改的记录!")
flag = False
End If

If flag = True Then
If dt.Select("id=" + Me.ID.Text.Trim()).Length = 0 Then
MessageBox.Show("数据库中没有此ID!")
flag = False
End If
End If
If flag = True Then
If (MessageBox.Show("你确认要修改这条记录吗?", "修改确认", MessageBoxButtons.OKCancel) = DialogResult.OK) Then
Dim sql As String = "UPDATE EMPLOYEEINFO SET ID = '" + Me.ID.Text.Trim() + "',NAME = '" + Me.Uname.Text.Trim() + "',AGE =" + Me.age.Text.Trim() + ",IN_DATE =" + Me.checkdate() + ",SEX ='" + Me.getsex() + "',TEL ='" + Me.pho.Text.Trim() + "' WHERE(ID = '" + Me.ID.Text.Trim() + "')"
Dim sqlcmd As SqlCommand
sqlcmd.Connection = sqlcon
sqlcmd.CommandText = sql
Try
sqlcon.Open()
sqlcmd.ExecuteNonQuery()
MessageBox.Show("修改成功!")
Me.BindDg()
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End If
End If

End Sub

End Class


运行时出现:
未处理的“System.NullReferenceException”类型的异常出现在 Data Projects01.exe 中。
其他信息: 未将对象引用设置到对象的实例。"
然后黄色箭头指向:sqlcmd.Connection = sqlcon,请问各位大虾,我该怎么做呢?小弟是个菜鸟,刚开始学习.NET,请大家多多指教!谢谢!!

[yz1199]

Dim sqlcmd As SqlCommand->Dim sqlcmd As new SqlCommand

[liach]

yz1199,Thank you very much!!!