How can I refactor this method?
<pre><code>private void Update_Record_Click(object sender, EventArgs e)  
    {  
        ConnectionClass.OpenConnection();  

        if (textBox4.Text == "" &amp;&amp; textBox2.Text == "")  
        {  
            MessageBox.Show("No value entred for update.");  
        }  
        else if (textBox4.Text != "" &amp;&amp; textBox2.Text != "")  
        {  
            SqlCommand cmd = new SqlCommand("update medicinerecord set quantity='" + textBox2.Text + "' where productid='"+comboBox1.Text+"'", ConnectionClass.OpenConnection());  
            cmd.ExecuteNonQuery();  

            cmd = new SqlCommand("update myrecord set price='" + textBox4.Text + "' where productid='" + comboBox1.Text + "'", ConnectionClass.OpenConnection());
            cmd.ExecuteNonQuery();
            ConnectionClass.CloseConnection();
        }
        else if (textBox2.Text != "")
        {
            SqlCommand cmd = new SqlCommand("update myrecord set quantity='" + textBox2.Text + "' where productid='" + comboBox1.Text + "'", ConnectionClass.OpenConnection());
            cmd.ExecuteNonQuery();
            ConnectionClass.CloseConnection();
        }
        else if (textBox4.Text != "")
        {
            SqlCommand cmd = new SqlCommand("update myrecord set price='" + textBox4.Text + "' where productid='" + comboBox1.Text + "'", ConnectionClass.OpenConnection());
            cmd.ExecuteNonQuery();
            ConnectionClass.CloseConnection();
        }  
}  
</code></pre>

<p>It's working correctly but I want to make it shorter so that it's easier to understand.  How can I refactor it?</p>
