public partial class Form1 : Form
{
private OdbcConnection myConnection;
private OdbcCommand myCommand;

public Form1()
{
    InitializeComponent();
    //
    myConnection = new OdbcConnection();
    myCommand = new OdbcCommand();
    //
    myConnection.ConnectionString = "DSN=C2MEXT01;UID=GZAEXTUSR01;PWD=EXTUSR";
    myCommand.Connection = myConnection;
}

private void button1_Click(object sender, EventArgs e)
{
    try
    {
        myConnection.Open();
        //
        myCommand.CommandType = CommandType.StoredProcedure;
        //myCommand.CommandText = "CALL C2MV5_SA.gva_odbc_PatientAdminData_O";
        myCommand.CommandText = "{CALL C2MV5_SA.gva_odbc_PatientAdminData_O(?,?)}";
        //
        OdbcParameter param1 = new OdbcParameter();
        param1.ParameterName = "ContactNr";
        param1.OdbcType = OdbcType.VarChar;
        param1.Size = 16;
        param1.Direction = ParameterDirection.Input;
        param1.Value = "9361429";
        //
        OdbcParameter param2 = new OdbcParameter();
        param2.ParameterName = "PatName";
        param2.OdbcType = OdbcType.VarChar;
        param2.Size = 128;
        param2.Direction = ParameterDirection.Output;
        //
        myCommand.Parameters.Add(param1);
        myCommand.Parameters.Add(param2);
        //
        myCommand.ExecuteNonQuery();               
        //               
        textBox1.Text = param2.Value.ToString();               
       //
        myConnection.Close();
    }
    catch (Exception e1)
    {
        MessageBox.Show("exception : " + e1.Message);
        if (myConnection.State == ConnectionState.Open)
        {
            myConnection.Close();
        }
    }
}
}