How to display specific database entries into a textbox on a WinForm application

Question

UPDATE: Thanks everyone, the code was not the issue, although the information regarding SQL injection was useful, my issue was that I was using an older version of my database w

Answer 1

Try this instead. Avoid building SQL statement dynamically the way you are doing it. You are opening your database to risks of SQL Injection. Used parameters insead.

using (var connection = new SqlConnection("connection string"))
{
    connection.Open();
    using (var cmd = new SqlCommand("SELECT * FROM Product WHERE ProductID=@MYVALUE", connection))
    {
        cmd.Parameters.Add("@MYVALUE", SqlDbType.VarChar).Value = textBox3.Text;
        SqlDataReader re = cmd.ExecuteReader();

        if (re.Read())
        {
            textBox4.Text = re["ProductTitle"].ToString(); // only fills using first product in table
            textBox5.Text = re["ProductPublisherArtist"].ToString();
            comboBox1.Text = re["ProductType"].ToString();
            textBox6.Text = re["Price"].ToString();
        }
        else
        {
            MessageBox.Show("Please enter a valid item barcode");
        }
    }
}