SQL Server database won't update new information - sql-server

Question

I don't understand it. This code should work, but there must be something I've done wrong.
Can anyone see what I've done wrong?
string username = tbNewUSER.Text.Trim();
string password = tbNewPass.Text.Trim();
string role = "USER";
string str = "insert into UserValidation (USERNAME, PASSWORD, ROLE) values ('" + username + "','" + password + "','" + role + "')";
MessageBox.Show(username + " Registered", "User registration",MessageBoxButtons.OK, MessageBoxIcon.Information);
clsDB.InsUpDel(str);
And this is the follow up:
public static int InsUpDel(string str)
{
if (!(conn.State == ConnectionState.Open))
conn.Open(); //open connection if closed
int numRows = 0; //counter that checks number of rows affected in the db
try
{
SqlCommand cmd = new SqlCommand(str, conn);
numRows = cmd.ExecuteNonQuery();
cmd = null;
}
catch (SqlException ex)
{
string errorMsg = ex.Message; //more code can be put here
}
if (conn.State == ConnectionState.Open)
conn.Close();
return numRows;
}
Thank you.

Answer 1

Side notes:
Always use parameters for your queries and never string concatenation. For fun see Bobby Tables
Do not use static, there are not many places you need this.
Dont share database connections, create them and destroy them as needed.
Do not store passwords as plain text ever!
Do not catch exceptions you do not plan to handle. Log them and rethrow (using throw;) or do not catch at all. This last one will help you figure out why "its not working"
Updated code
public void UpdateUser() {
var userModel = new UserModel {
Username = tbNewUSER.Text.Trim(),
Password = tbNewPass.Text.Trim(),
Role = "USER"
};
var result = UpdateUser(userModel);
}
public int UpdateUser(UserModel user)
{
const string str = "insert into UserValidation (USERNAME, PASSWORD, ROLE) values (#userName, #password, #role)";
using(var conn = new SqlConnection("your connection string here, hint best to get it from the app.config"))
using(var command = new SqlCommand(str, conn))
{
command.Parameters.Add(new SqlParameter("#userName", SqlDbType.VarChar, 255) {Value = user.UserName});
command.Parameters.Add(new SqlParameter("#password", SqlDbType.VarChar, 255) {Value = user.Password});
command.Parameters.Add(new SqlParameter("#role", SqlDbType.VarChar, 255) {Value = user.Role});
conn.Open();
return cmd.ExecuteNonQuery();
}
}
UserModel.cs
public class UserModel {
public string UserName {get;set;}
public string Password {get;set;}
public string Role {get;set;}
}