public void drop_test_database() {
			SqlConnection.ClearAllPools();
			var db = new SqlCommander(ConnectionString);
			db.ExecuteNonQuery($"drop database [{DbName}]");
		}
		public void create_empty_database() {
			var db = new SqlCommander(ConnectionString);
			db.ExecuteNonQuery($"create database [{DbName}]");
		}