// <summary>
        /// 删除符合条件的StudentsModel实体
        /// </summary>
        /// <param name="predicate"></param>
        /// <returns></returns>
        public bool DeleteMulitistudentsByCondition(Expression <Func <StudentsModel, bool> > predicate)
        {
            var result = false;

            try
            {
                result = dal_students.DeleteByCondition(predicate) > 0 ? true : false;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return(result);
        }