合并两个 Linq 查询
Union Two Linq Queries
我有两个 LinqToSql 查询 return 结果集:
var grResults = (from g in ctx.GeneralRequests
join rt in ctx.RequestTypes on g.RequestTypeId equals rt.RequestTypeId
join sub in ctx.Logins on g.SubmitterStaffId equals sub.LoginId
join onb in ctx.Logins on g.OnBehalfOfStaffId equals onb.LoginId
where sub.GadId == gadId
select new
{
Status = "Submitted",
RequestId = g.GeneralRequestId,
Submitter = sub.UserName,
OnBehalf = (onb == null ? string.Empty : onb.UserName),
RequestType = (rt == null ? string.Empty : rt.Description),
ProjectName = (g == null ? string.Empty : g.ProjectName) ,
Comments = (g == null ? string.Empty : g.Comments),
LastUpdate = g.LastUpdateDate
});
var grdResults = (from gd in ctx.GeneralRequestDrafts
join rt in ctx.RequestTypes on gd.RequestTypeId equals rt.RequestTypeId
into tempRequestTypes
from rt1 in tempRequestTypes.DefaultIfEmpty()
join onb in ctx.Logins on gd.OnBehalfOfStaffId equals onb.LoginId
into tempOnBehalf
from onb1 in tempOnBehalf.DefaultIfEmpty()
join sub in ctx.Logins on gd.SubmitterStaffId equals sub.LoginId
where sub.GadId == gadId
select new
{
Status = "Draft",
RequestId = gd.GeneralRequestDraftId,
Submitter = sub.UserName,
OnBehalf = (onb1 == null ? string.Empty : onb1.UserName),
RequestType = (rt1 == null ? string.Empty : rt1.Description),
ProjectName = (gd.ProjectName == null ? string.Empty : gd.ProjectName),
Comments = (gd.Comments == null ? string.Empty : gd.Comments),
LastUpdate = gd.LastUpdateDate
});
问题是当我尝试合并它们时。
var results = grResults.Union(grdResults).OrderByDescending(r => r.LastUpdate);
虽然两个单独的查询有记录,但return没有记录。
由于这 2 个查询似乎并不相互依赖,如果您只是想获得一个列表,则只需同时执行这两个查询并合并每个查询的结果。
var results = grResults.ToList().Union(grdResults.ToList())
.OrderByDescending(r => r.LastUpdate);
我有两个 LinqToSql 查询 return 结果集:
var grResults = (from g in ctx.GeneralRequests
join rt in ctx.RequestTypes on g.RequestTypeId equals rt.RequestTypeId
join sub in ctx.Logins on g.SubmitterStaffId equals sub.LoginId
join onb in ctx.Logins on g.OnBehalfOfStaffId equals onb.LoginId
where sub.GadId == gadId
select new
{
Status = "Submitted",
RequestId = g.GeneralRequestId,
Submitter = sub.UserName,
OnBehalf = (onb == null ? string.Empty : onb.UserName),
RequestType = (rt == null ? string.Empty : rt.Description),
ProjectName = (g == null ? string.Empty : g.ProjectName) ,
Comments = (g == null ? string.Empty : g.Comments),
LastUpdate = g.LastUpdateDate
});
var grdResults = (from gd in ctx.GeneralRequestDrafts
join rt in ctx.RequestTypes on gd.RequestTypeId equals rt.RequestTypeId
into tempRequestTypes
from rt1 in tempRequestTypes.DefaultIfEmpty()
join onb in ctx.Logins on gd.OnBehalfOfStaffId equals onb.LoginId
into tempOnBehalf
from onb1 in tempOnBehalf.DefaultIfEmpty()
join sub in ctx.Logins on gd.SubmitterStaffId equals sub.LoginId
where sub.GadId == gadId
select new
{
Status = "Draft",
RequestId = gd.GeneralRequestDraftId,
Submitter = sub.UserName,
OnBehalf = (onb1 == null ? string.Empty : onb1.UserName),
RequestType = (rt1 == null ? string.Empty : rt1.Description),
ProjectName = (gd.ProjectName == null ? string.Empty : gd.ProjectName),
Comments = (gd.Comments == null ? string.Empty : gd.Comments),
LastUpdate = gd.LastUpdateDate
});
问题是当我尝试合并它们时。
var results = grResults.Union(grdResults).OrderByDescending(r => r.LastUpdate);
虽然两个单独的查询有记录,但return没有记录。
由于这 2 个查询似乎并不相互依赖,如果您只是想获得一个列表,则只需同时执行这两个查询并合并每个查询的结果。
var results = grResults.ToList().Union(grdResults.ToList())
.OrderByDescending(r => r.LastUpdate);