将数据从文本框保存到 sql server 表时出错

Question

I have created a WPF desktop application before and I was able to write up the code to save data from a textbox to a table I created in sql server 2012. I tried to create a WPF Web browser application and the same code was not working to save my data to my sql database. I am now trying to create another WPF desktop application and the same code that worked the last time is not working anymore. Please look at my code and help.

private void savebuyers_Click(object sender, RoutedEventArgs e)
{
        string connectionstring = null;
        connectionstring = "Data Source=FRANCIS;Initial Catalog=Pam Golding;Integrated Security=SSPI";
        SqlConnection con = new SqlConnection(connectionstring);

        try
        {
            string query;
            query = "insert into buyers (name,number,email) values ('" + namebuyers.Text + "'," + Convert.ToInt32(numberbuyers) + ",'" + emailbuyers.Text + "')";
            SqlCommand command = new SqlCommand(query, con);
            message1.Text = "Data Saved Successfully!";
            con.Open();
            command.ExecuteNonQuery();
            con.Close();
        }
        catch
        {
            message1.Text = "Error While Saving Data!";
        }
}

Answer 1

You have missed the Text property of numberbuyers . So it is unable to cast object of type TextBox to type System.IConvertible . You can fix it like this:

Convert.ToInt32(numberbuyers.Text)

Also you should always use parameterized queries to avoid Sql Injection .