Linq语法学习

/// <summary>报销单是否被增值税引用
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public bool IsRefWithholding(string id)
        {
            var isRefWithholding = (from wh in _dataContext.Withholdings
                                    join clp in _dataContext.ClaimSheetBaseInProjects on wh.ClaimSheetBaseInProjectId equals clp.Id
                                    join cl in _dataContext.ClaimSheetBases on clp.bxdId equals cl.Id
                                    where cl.Id == id
                                    select wh).Count() > 0;
            return isRefWithholding;
        }

public void UpdateClaimSheetBaseForFrozen(ClaimSheetBaseDto item)
        {
            _dataContext.CommandTimeout = 180;
            if (item != null)
            {
                var claimSheetBase = _dataContext.ClaimSheetBases.Single(a => a.Id.Equals(item.Id));
                claimSheetBase.IsFrozen = item.IsFrozen;
                claimSheetBase.FrozenCode = item.FrozenCode;
                _dataContext.SubmitChanges();
            }
        }

public void DelectProjectPay(ClaimSheetBaseDto item)
        {
            if (item.IsMulPay.Equals(true))
            {
               
                var projectPay = _dataContext.ProjectPay.Where(o => o.ClaimSheetBaseId == item.Id);
                if (item.PaymentByReverseDto != null)
                {
                    _dataContext.ProjectPay.DeleteAllOnSubmit(projectPay);
                }                
            }
        }

/// <summary>添加附件
        /// 先删除后增加
        /// </summary>
        /// <param name="claimSheetBaseId"></param>
        /// <param name="?"></param>
        /// <returns></returns>
        public bool AddAttachmentWB(ClaimSheetBaseDto item)
        {
            if (item.AttachmentDtos != null)
            {
                var attachments = _dataContext.AttachmentWB.Where(a => a.ClaimSheetBaseId.Equals(item.Id));
                if (attachments != null && attachments.Count() > 0)
                {
                    _dataContext.AttachmentWB.DeleteAllOnSubmit(attachments);
                }
                var attachmentDtos = new List<AttachmentWB>();
                foreach (var attachment in item.AttachmentDtos)
                {
                    attachmentDtos.Add(RePackAttachment(attachment));
                }

                _dataContext.AttachmentWB.InsertAllOnSubmit(attachmentDtos);
            }
            _dataContext.SubmitChanges();
            return true;

        }