Proiz/Blanki_ekzamena/DataBase.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;

namespace Blanki_ekzamena
{
    internal class DataBase
    {
        static SqlConnection SqlConnection = new SqlConnection(@"Data Source=ngknn.ru;Initial Catalog=31P_Trifonova_PP;User ID=31П;Password=12357");
        public static void openConnection()
        {
            if (SqlConnection.State == System.Data.ConnectionState.Closed)
            {
                SqlConnection.Open();
            }
        }
        public static void closeConnection()
        {
            if (SqlConnection.State == System.Data.ConnectionState.Open)
            {
                SqlConnection.Close();
            }
        }
        public static SqlConnection GetConnection()
        {
            return SqlConnection;
        }

        public static SqlConnection connect()
        {
            string location = Environment.CurrentDirectory;
            location = location.Remove(location.Length - 9, 9);
            location = location.Insert(location.Length, "Database1.mdf");
            string connectionString = @"Data Source=ngknn.ru;Initial Catalog=31P_Trifonova_PP;User ID=31П;Password=12357";
            SqlConnection sqlConnection = new SqlConnection(connectionString);
            sqlConnection.Open();
            return sqlConnection;
        }
    }
}