连接SQL数据库问题

Dim str As String
        str = "Data Source=local;Initial Catalog=财务管理;integrated Security=true"
        Dim con As New SqlConnection(str)
        con.Open()
        Dim sql As String = "select * from 登录表 where user_name'" & TextBox1.Text.ToString().Trim() & "' and user_pwd'" & TextBox2.Text.ToString().Trim() & "' and User_des='" & ComboBox1.Text.ToString.Trim() & "' "
        Dim cmd As New SqlCommand(sql, con)
        Dim reader As SqlDataReader
        reader = cmd.ExecuteReader

        If reader.Read() = True Then
            Me.Hide()
            frm.Label1.Text =
            frm.Show()
            frm.Text = "欢迎您进入财务管理系统" & TextBox1.Text & "--" & ComboBox1.Text
        Else
            MsgBox("登录失败，请检查你用户名，密码，以及权限是否正确")
        End If


请高手帮忙检查下，这个程序中哪里有错误，运行时con.Open()出现了错误，但是我不知道怎么改？