Linq GroupJoin 使用

最新推荐文章于 2025-05-06 13:46:47 发布

转载最新推荐文章于 2025-05-06 13:46:47 发布 · 124 阅读

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原文链接：http://www.cnblogs.com/xachary/p/4027178.html

本文介绍了一种使用LINQ进行复杂数据处理的方法，包括多次GroupJoin操作、Where条件筛选、OrderBy排序以及Select选择等步骤，实现了从多个表中关联获取医院、服务和支付方式等信息，并最终形成便于展示的数据格式。

备忘:

var data = BoshccEntities.Current.TB_MB_1
                .GroupJoin(BoshccEntities.Current.TB_MB_2, o => o.HospitalID, m => m.MemberID, (t, m) => new { t, m })
                .GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.ServiceCode, s => s.DicNum, (o, s) => new { t = o.t, m = o.m, s })
                .GroupJoin(BoshccEntities.Current.TB_CM_3, o => o.t.PaymentMethodCode, p => p.DicNum, (o, p) => new { t = o.t, m = o.m, s = o.s, p })
                .Where(o =>
                    (isenable.HasValue ? o.t.IsEnable == isenable.Value : true)
                    && (hasHospital ? hospitalIDs.Contains(o.t.HospitalID) : true)
                    && (hasService ? o.t.ServiceCode == service : true)
                    && (hasPayment ? o.t.PaymentMethodCode == payment : true))
                .OrderBy(o => o.t.ID)
                .Select(o => new
                {
                    ID = o.t.ID,
                    HospitalID = o.t.HospitalID,
                    ServiceCode = o.t.ServiceCode,
                    PaymentMethodCode = o.t.PaymentMethodCode,
                    IsEnable = o.t.IsEnable,
                    Remark = o.t.Remark,

                    Hospital = o.m.FirstOrDefault(), //关键1
                    Service = o.s.FirstOrDefault(),
                    Payment = o.p.FirstOrDefault()
                })
                .ToList() //关键2
                .Select(o => new TB_MB_4
                {
                    ID = o.ID,
                    HospitalID = o.HospitalID,
                    ServiceCode = o.ServiceCode,
                    PaymentMethodCode = o.PaymentMethodCode,
                    IsEnable = o.IsEnable,
                    Remark = o.Remark,

                    HospitalName = o.Hospital == null ? "" : o.Hospital.HospitalName, //关键3
                    ServiceName = o.Service == null ? "" : o.Service.DicName,
                    PaymentName = o.Payment == null ? "" : o.Payment.DicName
                });