There is no argument given that corresponds to the require formal parameter

Question

I'm testing out mysql and c# stuff, I am only using a console application and will adapt it to a windows form in the future. There has been an error that has occurred and I can't seem to fix it.

Method:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace databaseTest
{
class Program
{
    private MySqlConnection connection; //connection property
    private string server;
    private string database;
    private string uid;
    private string password;

    static void Main(string[] args)
    {

        while (true)
        {
            Console.Clear();
            Program myProg = new Program();
            myProg.Initialize();
            Console.WriteLine("Choose item;");
            Console.WriteLine("<A> Add Record");
            Console.WriteLine("<B> Delete Record");
            Console.WriteLine("<C> Update Record");
            Console.WriteLine("<D> Show Record");
            Console.WriteLine("<E> Count Records");
            Console.WriteLine("<F> Search Records");
            Console.WriteLine("<X> Exit");
            ConsoleKeyInfo myKey = Console.ReadKey();
            if (myKey.Key == ConsoleKey.A)
            {
                myProg.Insert();
            }
        }
    }

    private void Initialize()
    {
        server = "localhost"; //local host (WAMP)
        database = "my_db"; //database name
        uid = "root"; //database username 
        password = ""; //database password
        string connectionString;
        connectionString = "SERVER=" + server + ";" + "DATABASE=" +
        database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";
        connection = new MySqlConnection(connectionString);
    }

    private bool OpenConnection()
    {
        try
        {
            connection.Open();
            return true;
        }
        catch (MySqlException ex)
        {
            //When handling errors, you can your application's response based 
            //on the error number.
            //The two most common error numbers when connecting are as follows:
            //0: Cannot connect to server.
            //1045: Invalid user name and/or password.
            switch (ex.Number)
            {
                case 0:
                    Console.WriteLine("Cannot connect to server.  Contact administrator");
                    break;

                case 1045:
                    Console.WriteLine("Invalid username/password, please try again");
                    break;
            }
            return false;
        }
    }

    private bool CloseConnection()
    {
        try
        {
            connection.Close();
            return true;
        }
        catch (MySqlException ex)
        {
            Console.WriteLine(ex.Message);
            return false;
        }
    }

    public void Insert()
    {
        List<databaseOperations.User> user = new List<databaseOperations.User>();
        databaseOperations.User x = new databaseOperations.User();
        Console.Clear();
        Console.WriteLine("---> Insert Record\n");
        Console.WriteLine("Enter numeric ID: (***)");
        int ID = int.Parse(Console.ReadLine());
        Console.WriteLine("Enter first name:");
        String firstName = Console.ReadLine();
        Console.WriteLine("Enter last name:");
        String lastName = Console.ReadLine();
        Console.WriteLine("Enter telephone:");
        String telephone = Console.ReadLine();
        x.ID = ID;
        x.firstName = firstName;
        x.lastName = lastName;
        x.telephone = telephone;
        user.Add(x);
        databaseOperations.InsertToDatabase(x);
    }
}
}

Dll method:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace databaseTest
{
    class databaseOperations
    {
        private MySqlConnection connection; //connection property
    private string server;
    private string database;
    private string uid;
    private string password;

    public class User
    {
        public int ID { get; set; }

        public string firstName { get; set; }

        public string lastName { get; set; }

        public string telephone { get; set; }
    }

    private void Initialize()
    {
        server = "localhost"; //local host (WAMP)
        database = "my_db"; //database name
        uid = "root"; //database username 
        password = ""; //database password
        string connectionString;
        connectionString = "SERVER=" + server + ";" + "DATABASE=" +
        database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";";
        connection = new MySqlConnection(connectionString);
    }

    private bool OpenConnection()
    {
        try
        {
            connection.Open();
            return true;
        }
        catch (MySqlException ex)
        {
            //When handling errors, you can your application's response based 
            //on the error number.
            //The two most common error numbers when connecting are as follows:
            //0: Cannot connect to server.
            //1045: Invalid user name and/or password.
            switch (ex.Number)
            {
                case 0:
                    Console.WriteLine("Cannot connect to server.  Contact administrator");
                    break;

                case 1045:
                    Console.WriteLine("Invalid username/password, please try again");
                    break;
            }
            return false;
        }
    }

    private bool CloseConnection()
    {
        try
        {
            connection.Close();
            return true;
        }
        catch (MySqlException ex)
        {
            Console.WriteLine(ex.Message);
            return false;
        }
    }
    public void InsertToDatabase(int ID, string firstName,  string lastName, string telephone)
    {
        string query = "INSERT INTO tbl_user (ID,First_Name,Last_Name,Telephone) VALUES('" + ID + "', '" + firstName + "','" + lastName + "','" + telephone + "')";
        if (this.OpenConnection() == true)
        {
            MySqlCommand cmd = new MySqlCommand(query, connection);
            cmd.ExecuteNonQuery();
            this.CloseConnection();
            Console.WriteLine("\n -->Record Added - Press enter to continue...");
            Console.ReadLine();
        }
    }
}
}

I'm trying to use the dll method for InsertToDatabase

The error I get is:

Error CS7036 There is no argument given that corresponds to the required formal parameter 'firstName' of 'databaseOperations.InsertToDatabase(int, string, string, string)

If I change

databaseOperations.InsertToDatabase(ID, firstName, lastName, telephone);

I get this error instead:

Severity Code Description Project File Line Error CS0120 An object reference is required for the non-static field, method, or property 'databaseOperations.InsertToDatabase(int, string, string, string)

Answer 1

You haven't created an instance of databaseOperations. The method databaseOperations.InsertToDatabase is an instance method.

Also, as you mentioned, you're new to c# - you should name classes with capital first letters (Pascal case) , and instances with lower case first letters (camel case): https://msdn.microsoft.com/en-us/library/x2dbyw72.aspx

I have written the example below assuming you've renamed your databaseOperations class to DatabaseOperations:

DatabaseOperations databaseOperations = new DatabaseOperations();
databaseOperations.InsertToDatabase(x.ID, x.firstName, x.lastName, x.telephone);

Note also that your DatabaseOperations class doesn't currently call Initialize. You probably need to call this from your constructor, e.g:

class DatabaseOperations
{
    public DatabaseOperations()
    {
        Initialize();
    }    

    // etc.
}