I have this query and I'm having trouble converting into a lambda expression
SELECT [dbo].[Prospects].[Id]
,[UserId]
,[NewId]
,[dbo].[Prospects].[Status]
FROM [dbo].[Prospects] join [dbo].[User] on [dbo].[User].Id = [dbo]. [Prospects].UserId
where [dbo].[Prospects].NewId = 3 and [dbo].[User].IsActive = 1
This is what i got, but it is not working
var result = Workspace.Prospects.Join
(Workspace.Users, pros => pros.UserId,
use => use.Id, (pros, use)
=> new { Prospect = pros, User = use}).Where
(both => both.User.IsActive == true && both.Prospect.NewId == idVacante)
.OrderBy(both => both.Prospect.Id).AsEnumerable().ToList();
List<Prospect> prospects = result.Cast<Prospect>().ToList();
It's not that hard. you can filter the tables before joining them
var result = Workspace.Prospects.Where(x=> x.NewId == 3)
.Join(Workspace.Users.Where(x => x.IsActive == 1),
p => p.UserId,
u => u.Id,
(p, u) => new { p.Id, p.UserId, p.NewId, p.Status })
Related
Need some help translating below query to LINQ.
;With BookingWithLastStatus
as
(
Select *, Rnk = ROW_NUMBER() over (partition by BookingId order by Id desc)
from BookingStatus
)
Select *
from BookingWithLastStatus
where Rnk=1 AND StatusId = 3
I've done LINQ below but it is not getting the correct records.
var BookStatus = from p in _context.Set<BookingStatus>()
where p.StatusId == 3
group p by p.BookingId into opt
select new {
BookingId = opt.Key,
Id = opt.Max(x => x.Id)
};
The SQL query is getting 1 record only which is correct and my LINQ is getting multiple records.
UPDATE:
I did like this:
Get all the BookingStatus first
var GetAllBookStatus = await _context.Set<BookingStatus>()
.ToListAsync();
Then do the filtering based from the SQL Query I need.
var FilteredBookStatus = GetAllBookStatus
.OrderByDescending( x => x.Id )
.GroupBy(person => person.BookingId)
.Select( group => new { Group = group, Count = group.Count() } )
.SelectMany( groupWithCount =>
groupWithCount.Group.Select( b => b)
.Zip(
Enumerable.Range( 1, groupWithCount.Count ),
( b, i ) => new {
b.Id,
b.BookingId,
b.BookingMWABId,
b.BookStatus,
b.CreatedBy,
b.CreatedDate,
b.Destination,
b.InternalStatus,
b.LineNum,
b.ModifiedBy,
b.ModifiedDate,
b.Module,
b.ReasonCode,
b.ReceivedBy,
b.RefNo,
b.StatusId,
b.TimeStamp,
RowNumber = i }
)
)
.Where(a => a.StatusId == 3 && a.RowNumber == 1)
.ToList();
But I'm not so confident on Getting all records, as it will grow some time. Is there anything I can change from my code?
With EF core 6.x, you can do the following. It is not optimal case as in your SQL, but should work:
var BookStatus =
from p in _context.Set<BookingStatus>()
group p by p.BookingId into g
select g.OrderByDescending(x => x.Id).First();
BookStatus = BookStatus.Where(p => p.StatusId == 3);
Or another variant
var BookStatus = _context.Set<BookingStatus>().AsQueryable();
BookStatus =
from d in BookStatus.Select(d => new { d.BookingId }).Distinct()
from p in BookStatus
.Where(p => p.BookingId == d.BookingId)
.OrderByDescending(p => p.Id)
.Take(1)
select p;
BookStatus = BookStatus.Where(p => p.StatusId == 3);
i'm trying rewrite query from native sql to linq lambda syntax (not linq query syntax)
LINQ (not work)
var result = _uow.Repository<TableA>().Get().AsNoTracking()
.GroupJoin(
_uow.Repository<TableB>().Get().AsNoTracking(),
a => new { a.TabNotesCodeId, a.TabLabelCodeId },
b => b.ElementNameId
(b, a) => new SubSection
{
SubSectionName = b.CustomValue ?? a.TabLabelCodeId,
SubSectionNote = b.CustomValue ?? a.TabLabelCodeId,
})
.Where(a => a.ResourceId == 1);
SQL
SELECT [SubSectionName] = ISNULL(B.CUSTOMVALUE,A.TABLABELCODEID),
[SubSectionNote] = ISNULL(B.CUSTOMVALUE,A.TABNOTESCODEID)
FROM TableA as A LEFT JOIN
(SELECT CUSTOMVALUE, ELEMENTNAMEID FROM TableB WHERE DISPLAYSETTINGID = 1) as B
ON B.ELEMENTNAMEID IN ( A.TABNOTESCODEID, A.TABLABELCODEID)
WHERE A.RESOURCEID = 1
Q How to rewrite sql ON B.ELEMENTNAMEID IN ( A.TABNOTESCODEID, A.TABLABELCODEID) to lambda syntax
...
a => new { a.TabNotesCodeId, a.TabLabelCodeId },
b => b.ElementNameId
....
(doesn't work)
Normally I would suggest following my SQL conversion rules, but this is sufficiently complex I don't think it would help.
To use query comprehension syntax on a non-equijoin that is a left join, it seems easiest to use lambda syntax to express the join conditions, so I just combined the sub-query with the join conditions:
var ans = from A in TableA
where A.ResourceID == 1
from B in TableB.Where(b => b.DisplaySettingID == 1).Where(b => b.ElementNameID == A.TabNotesCodeID || b.ElementNameID == A.TabLabelCodeID).DefaultIfEmpty()
select new {
SubSectionName = (B.CustomValue ?? A.TabLabelCodeID),
SubSectionNote = (B.CustomValue ?? A.TabNotesCodeID)
};
The lambda equivalent of multiple from clauses to generate a cross join is SelectMany, so converting into lambda syntax:
var ans2 = TableA.Where(a => a.ResourceID == 1)
.SelectMany(a => TableB.Where(b => b.DisplaySettingID == 1).Where(b => b.ElementNameID == a.TabNotesCodeID || b.ElementNameID == a.TabLabelCodeID)
.DefaultIfEmpty(),
(a, b) => new {
SubSectionName = (b.CustomValue ?? a.TabLabelCodeID),
SubSectionNote = (b.CustomValue ?? a.TabNotesCodeID)
}
);
After countless experiments i've found out solution:
_uow.Repository<TableA>().Get().AsNoTracking()
.GroupJoin(
_uow.Repository<TableB>().Get().AsNoTracking().Where(b => b.DisplaySettingId == 1),
a => new { note = a.TabNotesCodeId, label = a.TabLabelCodeId },
b => new { note = b.ElementNameId, label = b.ElementNameId },
(a, b) => new { a,b })
.Where(joinTables => joinTables.a.ResourceId == 1)
.SelectMany(
joinTables => joinTables.b.DefaultIfEmpty(),
(joinTables, b) => new SubSection()
{
LayoutTab = joinTables.a.LayoutTab,
SubSectionName = b.CustomValue ?? joinTables.a.TabLabelCodeId,
SubSectionNote = b.CustomValue ?? joinTables.a.TabNotesCodeId
});
Is it possible to join two from based on a local expression variable?
ex;
var query = from t in context.table1
from a in context.anothertable1.Where(x => t.id == a.id)
select new {a,t};
on line 2, the Where clause .Where(x => t.id == a.id) how would you move it into an expression?
I know i can do this;
Expression<Func<anothertable1, bool>> test = x => x.field1 == 1;
and It would work here;
var query = from t in context.table1
from a in context.anothertable1
.Where(x => t.id == a.id)
.Where(test)
select new {a,t};
and everything work and the sql query generated is as expected.
I can't figure out how to do the same with the other where.
EDIT
a more complex example, i anonymized it so it might not compile
var listOfMinMaxtable1 = (from n in context.table1.Where(table1Filter)
group n by n.table1_Number into grp
select new MinMaxtable1()
{
table1_Id_Max = grp.Max(x => x.table1_Id),
table1_Id_Min = grp.Min(x => x.table1_Id),
table1_Number = grp.Key
});
var listtable2 = (from t in context.table2
group t by t.table2_Id into grp
select new table2()
{
table2 = grp,
table2_Id = grp.Key
});
var query = from MinMax in listOfMinMaxtable1
//inner join **reference 1**
from table3 in context.table3
.Where(x => x.table_Number == MinMax.table_Number)
.Where(noticeMasterFilter) //a working expression<func<>>
//inner join **reference 2**
from Lasttable1 in context.table1
.Where(x => x.table_Id == MinMax.table_Id_Max)
//left join **reference 3**
from Firsttable1 in context.table1
.Where(x => x.table_Id == MinMax.table_Id_Min)
.Where(firstNoticeFilter) //a working expression<func<>>
.DefaultIfEmpty()
//left join **reference 4**
from Lasttable2 in listtable2
.Where(x => x.table_Id == MinMax.table_Id_Max)
.SelectMany(x => x.table2)
.Where(x => x.table2_Id == 123)
.OrderByDescending(x => x.table_Id)
.Take(1)
.DefaultIfEmpty()
if you find //left join reference 3 in the code above
that where clause; .Where(x => x.table_Id == MinMax.table_Id_Min)
might be sometime; .Where(x => x.table_Id == MinMax.table_Id_Max)
I could just copy/paste the whole from and change the where clause while adding noop pattern (an expression that return false and this make entity framework remove the whole thing so it doesn't affect the generated sql/result) with an expression on both from
for reference(this is noise to the question), the noop expression that i'm talking about is;
Expression<Func<table1, bool>> includeFrom= x => false;
and would be used like
//left join **reference 3**
from Firsttable1 in context.table1
.Where(x => x.table_Id == MinMax.table_Id_Min)
.Where(firstNoticeFilter) //a working expression<func<>>
.Where(includeFrom) //<--- this line make it a noop if the expression stay false
.DefaultIfEmpty()
but I don't want to do this if it's possible to make a custom expression that would go into the .Where()
Instead of creating an expression based on one type, you can create a combined type and use that for your where expression.
Two Table Combined Type
public class TwoTableDto
{
public Table1 t { get; set; }
public Table2 a { get; set; }
}
Query without expression
var query = (from t in context.table1
from a in context.anothertable1
select new TwoTableDto { t = t, a = a })
.Where(x => x.t.id == x.a.id);
Expression
Expression<Func<TwoTableDto, bool>> expr = x => x.t.id == x.a.id;
Query with expression
var query = (from t in context.table1
from a in context.anothertable1
select new TwoTableDto { t = t, a = a })
.Where(expr);
Combining Tables without JOIN keyword
var res2 = from u in dtEmp.AsEnumerable()
from v in dtDept.AsEnumerable()
where u.Field<int>("DepartmentID") == v.Field<int>("DepartmentID") &&
u.Field<double>("Salary") > 10000
select new
{
Name = u.Field<string>("Name"),
Department = v.Field<string>("DepartmentName")
};
How to do the same using Lambda Expression without using Join Keyword?
Do you mean you want to switch from SQL syntax to Method Chain syntax? i.e:
var res2 = dtEmp.AsEnumerable()
.SelectMany(u => dtDept.AsEnumerable(), (u, v) => new {u, v})
.Where(#t => u.Field<int>("DepartmentID") == v.Field<int>("DepartmentID") &&
u.Field<double>("Salary") > 10000).Select(#t => new
{
Name = u.Field<string>("Name"),
Department = v.Field<string>("DepartmentName")
});
Data structure looks like:
User(id)
UserApp(user_id, app_id)
UserSkill(user_id, skill_id)
Using linq-to-sql or EF, how would I construct a query to elegantly return only users who possess every requested app and skill?
In addition, how would I adjust the query to return any user who possesses at least one of the requested apps or skills? Essentially an OR vs AND (above).
UPDATE 1:
So I think we're close. Basically I want to only return users who have ALL the requested apps and skills. If we have two arrays of requested ids for skills and apps:
int[] requestedAppIDs // [1, 2, 3]
int[] requestedSkillIDs // [4, 5, 6]
I would only want to return a user if they have apps 1,2,3 AND skills 4,5,6.
var usersWithAllSelectedAppsAndSkills =
context.Users
.GroupJoin(context.UserApp,
k => k.id,
k => k.user_id,
(o, i) => new { User = o, UserApps = i })
.GroupJoin(context.UserSkill,
k => k.User.id,
k => k.user_id,
(o, i) => new { User = o.User, o.UserApps, UserSkills = i })
.Where(w => !requestedAppIDs.Except(w.UserApps.Select(x => x.app_id).ToArray()).Any() && !requestedSkillIDs.Except(w.UserSkills.Select(x => x.skill_id).ToArray()).Any())
.Select(s => s.User)
.ToList();
Obviously, LINQ does not know how to translate the UserSkills.Select().ToArray()'s in my Where() to SQL. How can I accomplish this?
And, secondarily the OR solution as well (user has any one of the requested apps or skills).
This will do the job as long as the user_id – app_id and user_id – skill_id values in the UserApp and UserSkill tables are unique.
var requestedSkillIDs = new[] { 4, 5, 6 };
var skillCount = requestedSkillIDs.Length;
var requestedAppIDs = new[] { 1, 2, 3 };
var appCount = requestedAppIDs.Length;
using (var context = new TestContext()) {
context.Database.CreateIfNotExists();
var appQuery = context.UserApp.Where(p => requestedAppIDs.Contains(p.AppId))
.GroupBy(p => p.UserId)
.Where(p => p.Count() == appCount);
var skillQuery = context.UserSkill.Where(p => requestedSkillIDs.Contains(p.SkillId))
.GroupBy(p => p.UserId)
.Where(p => p.Count() == skillCount);
var result = from a in appQuery
join s in skillQuery on a.Key equals s.Key
join u in context.Users on s.Key equals u.Id
select u;
var users = result.ToList();
}
Here's one way to do it, I hope i got all the syntax right :)
using (var context = new YourContext())
{
var usersWithAllSkills = context.User
.Where(w => w.id == yourId)
.Join(context.UserApp,
k => k.id,
k => k.user_id,
(o,i) => o)
.Join(context.UserSkill,
k => k.id,
k => k.user_id,
(o,i) => o)
.ToList();
var usersWithAnySkill = context.User
.Where(w => w.id == yourId)
.GroupJoin(context.UserSkill,
k => k.id,
k => k.user_id,
(o,i) => new { User = o, UserSkills = i })
.GroupJoin(context.UserApp,
k => k.User.id,
k => k.user_id,
(o,i) => new { User = o.User, o.UserSkills ,UserApps = i })
.Where(w => w.UserSkills != null || w.UserApps != null)
.Select(s => s.User)
.ToList();
}
For the first case (AND) You just need to make inner join like below:
from t1 in db.UserApp
join t2 in db.UserSkill on t1.user_id equals t2.user_id
where t1.app_id == "someID" && t2.skill_id == "someID"
select new { t1.user_id,t1.user_app_id, t2.user_skill}
For the second case just swap &&(AND) with ||(OR).
There is a more direct way to write the required queries using L2E. To write these queries you have to forget thinking in SQL and start thinking in LINQ.
For the first case, look for users which have all the skills:
var usersWithAll = ctx.Users2.Where(u =>
appIds.All(aid => u.Apps.Any(a => a.AppId == aid))
&& skillIds.All(sid => u.Skills.Any(s => s.SkillId == sid))
);
Translated as: get the users where, for all the appIds the user has al leat an app with that application id and for all skillIds the user has at least one skill with that id
And, for the second case, users which have any of the apps and any of the skills:
var usersWithAny = ctx.Users2.Where(u =>
appIds.Any(aid => u.Apps.Any(a => a.AppId == aid))
&& skillIds.Any(sid => u.Skills.Any(s => s.SkillId == sid))
).ToList();
Translated as: get the users where, for at least one appId the user has an app with that application id and for any skillIds the user has at least one skill with that id
If you run this test class, you'll also see the executed query (please, note that, to do so, I'm using the Log property of Database. I think it's only available from EF6 on).
namespace Tests
{
[TestClass]
public class CheckSeveralRelationsAtOnce
{
[TestMethod]
public void HasAllAppsAndSkills()
{
int[] appIds = {1, 2, 3};
int[] skillIds = {6, 7, 8};
using (var ctx = new MyDbContext())
{
ctx.Database.Log = Console.Write;
var usersWithAll = ctx.Users2.Where(u =>
appIds.All(aid => u.Apps.Any(a => a.AppId == aid))
&& skillIds.All(sid => u.Skills.Any(s => s.SkillId == sid))
).ToList();
Assert.IsNotNull(usersWithAll);
}
}
[TestMethod]
public void HasAnyAppsOrSkill()
{
int[] appIds = { 1, 2, 3 };
int[] skillIds = { 6, 7, 8 };
using (var ctx = new MyDbContext())
{
ctx.Database.Log = Console.Write;
var usersWithAny = ctx.Users2.Where(u =>
appIds.Any(aid => u.Apps.Any(a => a.AppId == aid))
&& skillIds.Any(sid => u.Skills.Any(s => s.SkillId == sid))
).ToList();
Assert.IsNotNull(usersWithAny);
}
}
}
}
I believe the answer by codeworx is correct for getting users with all the skills / apps
As an aside - I answered pretty much the same question recently with a pure SQL solution (SQL Server) - that could be turned into a stored procedure (with a table valued parameter) - See here if interested. This will perform better for a large number of values. Entity framework will turn every skill/app in the list into its own SQL parameter, which is much slower.
Unfortunately Entity framework doesn't really support table valued parameters yet - although you can use the entity framework connection to directly call a stored procedure with a table valued parameter (as per this article
Back to the question at hand...
I'll add the (easier) query to select a user with ANY of the skills & ANY of the apps:
var result = from u in context.Users
join _a in (
from a in context.UserApp
where requestedAppIDs.Contains(a.AppId)
select a.UserId;
) on u.Id equals _a
into aGrp
join _s in (
from s in context.UserSkill
where requestedSkillIDs.Contains(s.SkillId)
select s.UserId;
) on u.Id equals _s
into sGrp
where aGrp.Any()
&& sGrp.Any()
select u;
And just for completeness - the ALL solution again:
var skillCount = requestedSkillIDs.Length;
var appCount = requestedAppIDs.Length;
var result = from u in context.Users
join _a in (
from a in context.UserApp
where requestedAppIDs.Contains(a.AppId)
select a.UserId;
) on u.Id equals _a
into aGrp
join _s in (
from s in context.UserSkill
where requestedSkillIDs.Contains(s.SkillId)
select s.UserId;
) on u.Id equals _s
into sGrp
where aGrp.Count() == appCount
&& sGrp.Count() == skillCount
select u;
and finally - an example where the main query body is fixed, but you can add differing where clauses depending upon the AND/OR requirement
bool onlyReturnWhereAllAreMatched = false;
var skillCount = requestedSkillIDs.Length;
var appCount = requestedAppIDs.Length;
IQueryable<User> result;
var query = from u in context.Users
join _a in (
from a in context.UserApp
where requestedAppIDs.Contains(a.AppId)
select a.UserId;
) on u.Id equals _a
into aGrp
join _s in (
from s in context.UserSkill
where requestedSkillIDs.Contains(s.SkillId)
select s.UserId;
) on u.Id equals _s
into sGrp
select new {u, aCount = aGrp.Count(), sCount = sGrp.Count()};
if (onlyReturnWhereAllAreMatched)
{
result = from x in query
where x.aCount == appCount
&& x.sCount == skillCount
select x.u;
} else {
result = from x in query
where x.aCount > 0
&& x.sCount > 0
select x.u;
}