SELECT t_PersonalInformation.personalInformation_Name, t_PersonalInformation.personalInformation_PresentAddress,
t_PersonalInformation.personalInformation_PermanentAddress, t_PersonalInformation.personalInformation_Phone,
t_PersonalInformation.personalInformation_Email,
t_Applicant.applicant_TotalExperience,
t_Experience.experience_CompanyName, CAST( t_Experience.experience_EndingYear AS INT) - CAST( t_Experience.experience_JoiningYear AS INT) AS yearOfExperience ,
t_Experience.experience_Responsibilities,
t_Training.training_TitleDetails, t_Training.training_Institute,
t_Training.training_Year, t_Training.training_Duration
FROM t_Applicant LEFT OUTER JOIN
t_PersonalInformation ON t_Applicant.applicant_user_ID = t_PersonalInformation.personalInformation_applicant_ID
LEFT OUTER JOIN
t_Experience ON t_Applicant.applicant_user_ID = t_Experience.experience_applicant_ID
LEFT OUTER JOIN
t_Training ON t_Applicant.applicant_user_ID = t_Training.training_applicant_ID
WHERE (t_Applicant.applicant_user_ID = 'hasib789')
i am using in C# with VS2008
I don't really have the time to go through all of that, but I can give you an idea of how it's done.
var query = from var applicant in t_Applicant
from perInf in t_PersonalInformation.Where(per => applicant.applicant_user_ID = per.personalInformation_applicant_ID).DefaultIfEmpty()
where applicant.applicant_user_ID == "hasib789"
select new ClassName{
Name = perInf!=null ? perInf.personalInformation_Name : <default value>,
PresentAddress = perInf!=null ? perInf.personalInformation_PresentAddress: <default value>,
...
etc
}
That second 'from' statement is one of the ways to do an outer join. That DefaultIfEmpty allows it to generate a new record of ClassName even if no matching record for perInf is found. Once you actually go to assign the values in your new record at the bottom, you have to check for null.
Using that template you should be able to get the rest of the query built.
Related
I'm having trouble getting my Linq statemnt to work when doing an outer join and a group by. Here's a SQL version of what I'm trying to accomplish:
select p.PRIMARY_KEY, min(p.EFFECTIVE_DATE), sum(IsNull(c.PAID_INDEMNITY, 0))
from PRMPOLCY p
left outer join CLMMAST c on p.PRIMARY_KEY = c.POLICY_NO
where p.UNDERWRITER_UID = 93
GROUP BY p.PRIMARY_KEY
Here's what I have in Linq (which doesn't work):
var result = from p in context.PRMPOLCies
join c in context.CLMMASTs on p.PRIMARY_KEY equals c.POLICY_NO into polClm
where (p.UNDERWRITER_UID == underwriter)
from grp in polClm.DefaultIfEmpty()
group grp by p.PRIMARY_KEY into g
select new PolicySummation()
{
PolicyNo = g.Key,
Incurred = g.Sum(grp => grp.PAID_INDEMNITY ),
EffDate = g.Min(grp => grp.PRMPOLCY.EFFECTIVE_DATE
};
Beating my head against the wall trying to figurwe this out!
Assuming you have a navigation property set up between PRMPOLCY and CLMMAST, you shouldn't need to specify the join explicitly. It's much easier to express most queries in linq without explicit joins, but rather treating your structures as a hierarchy. I don't know the specifics of your model property names, but I'd take a guess that something like this would work.
var result =
from p in context.PRMPOLCies
where (p.UNDERWRITER_UID == underwriter)
select new PolicySummation {
PolicyNo = p.PRIMARY_KEY,
Incurred = p.CLMASTs.Select(c => c.PAID_INDEMNITY).DefaultIfEmpty().Sum(),
EffDate = p.EFFECTIVE_DATE,
};
You need to include both your tables in the group clause like this:
group new { p, grp } by p.PRIMARY_KEY into g
Then in your Sum / Min
g.Sum(grp => grp.grp == null ? 0 : grp.grp.PAID_INDEMNITY )
g.Min(grp => grp.p.PRMPOLCY.EFFECTIVE_DATE)
I am trying to do a left outer join on three tables. I know there is a way to do it in one variable but I haven't been able to figure it out. Instead I have performed two separate left outer joins and then did a left out join on those. Here is my code for that:
var outerJoin1 =
(from h in resultHours
join u in results on new {h.PhysicalUnitId, h.MonthNum} equals new {u.PhysicalUnitId, u.MonthNum} into outer
from grouping in outer.DefaultIfEmpty()
select new {timeKey = h, Key = grouping});
var outerJoin2 =
(from h in resultHours
join s in serviceHrsResults on new {h.PhysicalUnitId, h.MonthNum} equals new {s.PhysicalUnitId, s.MonthNum} into outer2
from grouping in outer2.DefaultIfEmpty()
select new {timeKey = h, Key = grouping});
var outerJoin =
(from a in outerJoin1
join b in outerJoin2 on new {a.timeKey.PlantId, a.timeKey.MonthNum} equals new {b.timeKey.PlantId, b.timeKey.MonthNum} into outer
from grouping in outer.DefaultIfEmpty()
select new{timeKey = a, Key = grouping}).Distinct();
I have tried putting the above together in one variable I can't get it to work. Here is what I have tried:
var outerjoin =
from h in resultHours
join u in results on new {h.PhysicalUnitId, h.MonthNum} equals new {u.PhysicalUnitId, u.MonthNum} into outer
from grouping in outer.DefaultIfEmpty()
from hr in resultHours
join s in serviceHrsResults on new {hr.PhysicalUnitId, hr.MonthNum} equals new {s.PhysicalUnitId, s.MonthNum} into outer2
from grouping in outer2.DefaultIfEmpty()
select new {timeKey = h && timeKey = hr, Key = grouping};
The problem with this is the two groupings conflict. i'm pretty sure I just need a single grouping right before the select but cannot figure out how to use the "grouping in" and include both outer.DefaultIfEmpty() and outer2.DefaultIfEmpty().
I would appreciate it if someone could enlighten me.
You are using duplicate range variable ids - you've got 2x grouping.
- Which grouping is it that you want in the result set ?
- What is this line expected to achieve?
timeKey = h && timeKey = hr - how do you want to combine those in the projection ?
I would try the query below, but I've changed the select part of it as your combined version doesn't make sense to me.
Let me know if it at all works for you as without data it's not easy to test this, so I can't be sure that the new version is fine.
var outerjoin =
from h in resultHours
join u in results on new {h.PhysicalUnitId, h.MonthNum} equals new {u.PhysicalUnitId, u.MonthNum} into outer
from grouping1 in outer.DefaultIfEmpty()
//from hr in resultHours
join s in serviceHrsResults on new {grouping1.PhysicalUnitId, grouping1.MonthNum} equals new {s.PhysicalUnitId, s.MonthNum} into outer2
from grouping2 in outer2.DefaultIfEmpty()
select new {timeKey = h, Key1 = grouping1, Key2 = grouping2};
I wonder if anyone can help
I have a simple SQL Query which was this.
SELECT * FROM ITEM INNER JOIN CODES ON ITEM.ITEMID = CODES.ITEMID AND
ITEM.CATID = CODES.CATID
This works great, so i created the following query in LINQ
from i in Item join c in codes
on new { i.itemid, i.catid } equals new { c.itemid, c.catid }
Works great, but they i realized that i actually needed an LEFT JOIN in place of the INNER JOIN. So the sql, which now works great!, is :- (notice left join)
SELECT * FROM ITEM LEFT JOIN CODES ON ITEM.ITEMID = CODES.ITEMID AND
ITEM.CATID = CODES.CATID
So now everything seems to work and i get back the data i require using SQL i can't figure out how to do a left join in LINQ and especially how to do a left join on more than 1 field - in my case itemid and catid
I wonder if anyone can lend a hand, i am stuck :-)
I think this is the direction you need to head down:
from i in Item
join c in codes on new { i.itemid, i.catid } equals new { c.itemid, c.catid }
into grouped
from g in grouped.DefaultIfEmpty()
select new
{
ItemId = c.itemid,
CatItemId = g != null ? g.itemid : "Empty"
};
You should look: http://codingsense.wordpress.com/2009/03/08/left-join-right-join-using-linq/
The key is -->
into JoinedEmpDept
from dept in JoinedEmpDept.DefaultIfEmpty()
Can anyone help?
I have 1 class, basically it holds Members and within that class is a List.
The members i have in a List also... So basically it goes like this,
I have 2 members and each member has a number of sessions.
I wish to only return each member with 1 Session.
I have done a LINQ query, but of course it doesn't work...
I think i need to do a self join, any ideas?
Basically my error is m doesn't exist in my subquery self join.
var sessions =
from m in this.members
join s in
(
from se in m.Sessions
group se by se.Name into g
select new {Name = g.Key, SessioEndTime = g.Max(a=>a.SessioEndTime)}
)
on m.Name equals s.Name
select new { MemberName = m.Name, SessionTime = s.SessioEndTime}
I would appreciate any feedback anyone has.
Thanks in advance.
EDIT
Ok i managed to do it like the following, but is this the best way?
var sessions =
from m in this.members
let sn = m.Sessions.OrderByDescending(a => a.SessionEndTime).FirstOrDefault()
select new { MemberName = m.Name, SessionTime = sn.SessioEndTime}
This way sn contains 1 record, but i have access to all the properties...
But is this the best way to do using a LET?
Thanks.
Unless I am missing something you need this, no?
var sessions =
from m in members
select new {
MemberName = m.Name,
SessionTime = m.Sessions.Max(s => s.SessioEndTime)
};
You have to change the way you think about LINQ queries, think more from object point rather than from SQL implementation point. What is it that I need? I need all members, each with its latest session end time, then act on that.
EDIT:
The let option you used is ok, just keep something in mind FirstOrDefault will return null if member has an empty list of Sessions, and then sn.SessionEndTime hits null reference. If on the other hand you are certain that every member has at least one session use First instead or aggregate.
Also don't use FirstOrDefault() in the let, it kind of messes up the LINQ and prevents it from tying it to the master (causing a separate SQL query for each master to detect missing subsets), so usable queries with let are:
from m in Members
let sn = m.Sessions.Max(s => s.SessioEndTime)
select new { MemberName = m.Name, SessionTime = sn};
from m in Members
let sn = m.Sessions.OrderByDescending(a => a.SessioEndTime).First()
select new { MemberName = m.Name, SessionTime = sn.SessioEndTime};
As for ordering vs Max aggregation, both queries will generate a subquery:
-- MAX
SELECT [t0].[Name] AS [MemberName], (
SELECT MAX([t1].[SessioEndTime])
FROM [Session] AS [t1]
WHERE [t1].[memberId] = [t0].[id]
) AS [SessionTime]
FROM [Member] AS [t0]
GO
-- ordering
SELECT [t0].[Name] AS [MemberName], (
SELECT [t2].[SessioEndTime]
FROM (
SELECT TOP (1) [t1].[SessioEndTime]
FROM [Session] AS [t1]
WHERE [t1].[memberId] = [t0].[id]
ORDER BY [t1].[SessioEndTime] DESC
) AS [t2]
) AS [SessionTime]
FROM [Member] AS [t0]
With a descending index on SessioEndTime the ordering script is about twice slower (you can get execution plans for these to check for yourself), without the index its about 5times slower.
I have the following SQL query:-
select distinct * from dbo.Profiles profiles
left join ProfileSettings pSet on pSet.ProfileKey = profiles.ProfileKey
left join PlatformIdentities pId on pId.ProfileKey = profiles.Profilekey
I need to convert it to a LinqToEntities expression. I have tried the following:-
from profiles in _dbContext.ProfileSet
let leftOuter = (from pSet in _dbContext.ProfileSettingSet
select new
{
pSet.isInternal
}).FirstOrDefault()
select new
{
profiles.ProfileKey,
Internal = leftOuter.isInternal,
profiles.FirstName,
profiles.LastName,
profiles.EmailAddress,
profiles.DateCreated,
profiles.LastLoggedIn,
};
The above query works fine because I haven't considered the third table "PlatformIdentities". Single left outer join works with what I have done above. How do I include PlatformIdentities (the 3rd table) ? I basically want to translate the SQL query I specified at the beginning of this post (which gives me exactly what I need) in to LinqToEntities.
Thanks
Let me know if you want to select something different, but a true join is below
from p in _dbContext.ProfileSet
join ps in _dbContext.ProfileSettings on p.ProfileKey = ps.ProfileKey into a
join pi in _dbContext.PlatformIdentities on p.ProfileKey = pi.ProfileKey into b
select new
{
profiles.ProfileKey,
profiles.FirstName,
profiles.LastName,
profiles.EmailAddress,
profiles.DateCreated,
profiles.LastLoggedIn,
PlatformSettings = a.Select(x=>x),
PlatformIdentities = b.Select(y=>y)
}