Cấu phần kết nối các loại CSDL.

CheckNumber.cs

using System;

namespace COP {
	class CheckNumber {
		public bool isNguyenTo(int a) {
			if (a == 0 || a == 1) 
				return false;
			for(int i = 2; i <= Math.Sqrt(a); i++) {
				if (a % i == 0)
					return false;
			}
			return true;
		}
		
		public bool isChinhPhuong(int a) {
			return (a == (int)(Math.Sqrt(a)) * (int)(Math.Sqrt(a)));
		}
		
		public bool isHoanHao(int a) {
			int tong = 1;
			for (int i = 2; i <= a/2; i++) {
				if (a % i == 0)
					tong += i;
			}
			if (tong == a) 
				return true;
			else
				return false;
		}
	}	
}

// How to use: Plese implement following code into your application.
// if(CheckNumber.isNguyenTo(int number_to_check)) { // Todo Something }
// Similar to isChinhPhuong(), isHoanHao()

ConnectDB.cs

using System;
using System.Data.SqlClient;

namespace COP {
    class ConnectDB {
        public static SQLServer = 1;
        public static MySql = 2;
        public static Access = 3;
        
        private static SqlConnection connect;
        
        public static void Connect(int ServerName, string Server, string db, string userId = "", string Pwd = "") {
            string strCon = "";
            switch (ServerName) {
                case 1: 
                    strCon = "Server = " + Server + ";Database = " + db + ";User Id = " + userId + ";Password = " + Pwd + ";";
                    break;
                case 2:
                    strCon = "Server = " + Server + ";Database = " + db + ";Uid = " + userId + ";Pwd = " + Pwd + ";";
                    break;
                case 3:
                    strCon = "Driver = {Microsoft Access Driver (*.mdb, *.accdb)}; Dbd = " + db + "; Uid = " + userId + ";Pwd = " + Pwd + ";";
                    break;
            }
            
            
            connect = new SqlConnection(strCon);
            connect.Open();
        }
    }
}


// How to use: Implement following code into your application
// ConnectDB.Connect(ConnectDB.SQLServer, "localhost", "database_name", "user_name", "password");
// ConnectDB.Connect(ConnectDB.MySql, "localhost", "database_name", "user_name", "password");