Changing a row safely

An update changes an existing row. The pattern is the same as a parameterised read, with an important extra check.

The command

using (var conn = new SqlConnection(connString))
using (var cmd = new SqlCommand(
    "UPDATE Product SET Name = @name WHERE Id = @id", conn))
{
    cmd.Parameters.AddWithValue("@name", txtName.Text.Trim());
    cmd.Parameters.AddWithValue("@id", productId);
    conn.Open();
    int changed = cmd.ExecuteNonQuery();
    statusLabel.Text = changed + " row updated";
}

Why check the count

The execute method returns how many rows changed. If the answer is zero, the record was not found. If it is more than one, your condition matched too much. Either way, you want to know.

Creating a row is the mirror of this, covered in adding a new row.