Question

I’m working with C # in Visual Studio Express 2012. I work exclusively with desktop applications.
  As database I use MySQL

  The connection between the database and MySQL is working perfectly.

  My doubt is about making searching and return the result.

  Of all the examples I’ve seen, the most common is to create a method in my class MySQL enter code hereconnection that will return a list with the search result. I really do not know if this is conceptually more correct, but it seems very acceptable.

  I managed to do a search that returns all customers from my table. But my big question is: how to make this generic method?

  Eg

  My form has a button that triggers the click event:

dbConnect = new DBConnect();
dbConnect.OpenConnection();
private List<Clients> listSQLQuery; 
listSQLQuery = dbConnect.Select("select * from  clients");
datagridview.DataSource = listSQLQuery;

My method dboConnect.Select() used above:

public List<Clients> Select(string query)
{        


    //Create a list to store the result
    List<Clients> list = new List<Clients>();
   Clients clients = new Clients();


    //Open connection
    if (this.OpenConnection() == true)
    {
        //Create Command
        MySqlCommand cmd = new MySqlCommand(query, connection);
        //Create a data reader and Execute the command
        MySqlDataReader dataReader = cmd.ExecuteReader();

        //Read the data and store them in the list
        while (dataReader.Read())
        {
            clients.Id = dataReader["Id"].ToString();
            clients.Name = dataReader["Name"].ToString();
            list.Add(cliente);
        }

        //close Data Reader
        dataReader.Close();

        //close Connection
        this.CloseConnection();

        //return list to be displayed
        return list;
    }
    else
    {
        return list;
    }
}

And finally, my class Clients

public class Clients
{
    public string Id { get; set; }
    public string Name { get; set; }
}

This all works, but is very specific to a query with a Client.

  If now I make a call listSQLQuery=dbConnect.Select(“select * from products”) this method will not work, because it was built using as return a list of Clients and not of Products.

  I do not know if I could be clear in my question, but I wish I could make calls like without worrying if its gonna be a client, a product or a room.

Something like this:

listSQLQuery.dbConnect.Select("select * from clients");
listSQLQuery.dbConnect.Select("select * from products");
listSQLQuery.dbConnect.Select("select * from rooms");

   Is there any way to get a generic list return, without worrying about the type of listQuerySQL? I just wanna bind this list to a datagridview.

I am pretty novice in C#, so I dont know anything about LINQ, Entity Framework…

Answer 1

I agree with the other commentators, if you learn EF and LINQ It will make your life much more easier.

Entity Framework Video

Introduction to LINQ Video
Introduction to LINQ Queries Webpage
Lots of LINQ examples C#

In terms of your solution perhaps you can just make 3 different Select Methods: SelectClients, SelectProduct and SelectRooms. You will need to change a bit of the code so that it only opens and closes the connection once.