Fwd: cant insert into a post gre sql table...Can u please help in fixing this

  string employee = "insert into  VSP_Employee values ('" + txtEmpid.Text + "','" + txtEmpname.Text + "','" + txtEmailid.Text + "','" + txtphnum.Text + "','" + txtDOB.Text + "','"  +txtDOJ.Text + "','" + txtNOD.Text + "','" + txtSalary.Text + "','" + txtLeavestaken.Text + "','" + txtLeavesBalance.Text + "','" + txtPlannedleaves.Text+"')";

                    NpgsqlDataAdapter da = new NpgsqlDataAdapter(employee, conn);

                    cmd = new NpgsqlCommand(employee, conn);

                    da = new  NpgsqlDataAdapter(cmd);

                    ds = new DataSet();

                    da.Fill(ds, "VSP_Employee");