原创switch(T obj)选择语句如何判断是某一个对象

        /// <summary>
        /// 判断警单是否存在
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="ajbh">案件编号</param>
        /// <param name="obj">对象实例(T1,T2,T3)</param>
        /// <returns>true为存在，false为不存在</returns>
        public bool GetCase<T>( string ajbh, T obj )
        {
            if (string.IsNullOrEmpty( ajbh ))
            {
                return true;
            }
            if (obj is Nullable)
            {
                return true;
            }
            int count = 0;
            string sql = string.Empty;
            switch (obj.GetType().Name.ToLower())
            {
                case "t1":
                    sql = string.Format( "select count(*) from t_case_1 t where t.bh='{0}'", ajbh );
                    break;
                case "t2":
                    sql = string.Format( "select count(*) from t_case_2 t where t.bh='{0}'", ajbh );
                    break;
                case "t3":
                    sql = string.Format( "select count(*) from t_case_3 t where t.bh='{0}'", ajbh );
                    break;
            }

            if (string.IsNullOrEmpty( sql ))
            {
                return true;
            }
            using (DbCommand cmd = database.GetSqlStringCommand( sql ))
            {
                count = Convert.ToInt32( database.ExecuteScalar( cmd ) );
            }
            if (count > 0)
            {
                return true;
            }
            else
            {
                return false;
            }
        }