C#

private void btnSave_Click(object sender, EventArgs e)
        {
            try
            {
                if (txtFirstName.Text == "")
                    MessageBox.Show("Patient's First Name can't be blank", "Incomplete data", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                else if (txtDOB.Text == "")
                    MessageBox.Show("Patient's Date of Birth can't be blank", "Incomplete data", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                
                if (txtLastName.Text == "")
                    txtLastName.Text = " ";
                bool gender = true;
                if (!rbMale.Checked)
                    gender = false;

                MRMDbDataSetTableAdapters.PatientsDetailsTableAdapter pdta = new MediRecordManager.MRMDbDataSetTableAdapters.PatientsDetailsTableAdapter();
                if (pdta.AddNewPatient(txtFirstName.Text, txtLastName.Text, calDOB.SelectionStart, (byte)cbBloodGroup.SelectedValue, gender) > 0)
                {
                    MessageBox.Show("Data inserted to database !");
                    btnCancel.Text = "Close";
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }

OriginalGriff wrote:

Typing in the three relevent words from your question, the top hit was the answer.

OriginalGriff wrote:

I like to check my answers - nothing worse than wrong advice from somewhere full of "experts"!

string.Format("{0:0.0E2}", 0.000597);

string.Format("{0:#.0#E-00}", 1000000);