Tukukkk

I am making an application that allow users to register and their details are stored in a SQLite database. There is nothing wrong with the code down below but I want to know if I can make it more efficient.

I am making this application for my a level computing course work and there is an emphasis on the efficiency of our code which is why I want to know if I can make my code more efficient. The database is called users and I want to store the names usernames and passwords of the users in the database.

if (File.Exists("users.sqlite"))

    {

        SQLiteConnection con = new SQLiteConnection("Data Source=users.sqlite;Version=3;");



    try

    {

        con.Open();

        string Query = "insert into user_info (name, username, password) values ('" + fullname + "', '" + username + "','" + password + "')";



        SQLiteCommand cmd = new SQLiteCommand(Query, con);

        cmd.ExecuteNonQuery();

        con.Close();

    }

    catch (Exception)

    {

        MessageBox.Show("Error registering the user", "Please try again");



    }

}

else

{



    SQLiteConnection.CreateFile("users.sqlite");



    SQLiteConnection con = new SQLiteConnection("Data Source=users.sqlite;Version=3;");

    con.Open();



    string sql = "create table user_info (name varchar(20),username varchar(20),password varchar(20))";



    SQLiteCommand command = new SQLiteCommand(sql, con);

    command.ExecuteNonQuery();



    sql = "insert into user_info (name, username, password) values ('" + fullname + "', '" + username + "','" + password + "')";



    command = new SQLiteCommand(sql, con);

    command.ExecuteNonQuery();



    con.Close();

}

• Create objects before opening the connection.


• Limit the number of connection open/close cycles.


• Handle "outliers" up front to eliminate exception handling structures. I.E. creating the database file.


• Descriptive variable names.


• Invert boolean logic to eliminate unnecessary control structure.


• TODO
  
  
  
  
  • Catch specific exceptions so you can know what crashed. i.e. creating the table vs inserting data.
  
  
  • Put exception object details in the error message to help know what happened
  
  
  • Research the using keyword, how it's used to with data adapter connection objects. Facilitates automatic destruction of objects after use.
  
  
  
  

.

 SQLiteConnection users = new SQLiteConnection("DataSource=users.sqlite;Version=3;");

 string insert = "insert into user_info (name, username, password) values ('" + fullname + "', '" + username + "','" + password + "')";

 SQLiteCommand insertCmd = new SQLiteCommand(Query, con);

 SQLiteCommand createDbCmd = CreateDB();



 try

 {

    users.Open();

    if(createDbCmd != null) createDbCmd.ExecuteNonQuery();

    insertCmd.ExecuteNonQuery();

    users.Close();

 }

 catch (Exception)

 {

    MessageBox.Show("Error registering the user", "Please try again");

 }







 // returns null if file exists

 public SQLiteCommand CreateDB() 

 {

     if (File.Exists("users.sqlite")) return null;



     SQLiteConnection.CreateFile("users.sqlite");

     string sql = "create table user_info (name varchar(20),username varchar(20),password varchar(20))";

     SQLiteCommand cmd = new SQLiteCommand(sql, con);

     return new SQLiteCommand(sql, con);

}