I have a syntax problem and need some smart folks than me.
Here is my select statement
var Materials = from j in db.Jobs
join je in db.a_Job_Extensions on j.Top_Lvl_Job equals je.Job
join mr in db.Material_Reqs on j.Job1 equals mr.Job
join m in db.Materials on mr.Material equals m.Material1
where jobList.Contains(j.Top_Lvl_Job)
select new
{
je.PCR,
mr.Job,
j.Top_Lvl_Job,
OrderQty = ((from j1 in db.Jobs where j1.Job1 == j.Top_Lvl_Job select new { j1.Order_Quantity}).FirstOrDefault()).ToString(),
j.Part_Number,
mr.Material,
mr.Description,
mr.Est_Qty,
m.Status,
theClass = m.Class == null? "": m.Class
};
The j1.Order_Quantity is a double in the Job table. But when I run the query, it returns a value of "{ Order_Quantity = 607 }".
My desire is to have it return just the value of "607".
What am I doing wrong here?
The code was originally trying to bring it out as a double, but I switch to string to see what was coming out. I'm coming from a sql background so I must be missing something silly.
Try this
((from j1 in db.Jobs where j1.Job1 == j.Top_Lvl_Job select
j1.Order_Quantity.ToString()).FirstOrDefault())
Related
Please note below is entirely made up for example sake. I have a similar query based on an sql code but couldn't translate it to LINQ to get correct value.
The sql basically looks like this:
select * from customers c
join proucts p on c.id = p.customerid
join credit r on r.customerid=c.id and ISNULL(r.trandate, c.registeredDate) >= c.registeredDate
I also tried to tweak the above sql and put the condition inside where and it also returns the same value I am getting in my #2 LINQ below(which is incorrect).
How can I use c (customer) inside .Where of credit? see code
1.
from c in customers
join p in products on c.id = p.customerid
join cr in credit.Where(r=> r.tranDate => c.registeredDate!=null?c.registeredDate : r.purchaseDate) on c.id=cr.customerid
...
2.
I know you would suggest why not just put it in a where below like below but I am getting incorrect value.
from c in customers
join p in products on c.id = p.customerid
join cr in credit on c.id=cr.customerid
where r.tranDate => c.registeredDate!=null?c.registeredDate : r.purchaseDate
Is there a workaround? I have tried tons of others but won't get me the correct one.
LINQ supports only equijoins. Any additional criteria should go to where clause. And yes, the other range variables are inaccessible from the join inner sequence, so the filtering should happen before or after the join.
So this SQL query:
select * from customers c
join products p on c.id = p.customerid
join credit r on r.customerid = c.id
and ISNULL(r.trandate, c.registeredDate) >= c.registeredDate
directly translates to this LINQ query:
from c in customers
join p in products on c.id equals p.customerid
join cr in credit on c.id equals cr.customerid
where (cr.tranDate ?? c.registeredDate) >= c.registeredDate
select new { c, p, cr };
Optionally, the condition
(cr.tranDate ?? c.registeredDate) >= c.registeredDate
can be replaced with
(cr.tranDate == null || cr.tranDate >= c.registeredDate)
I have two tables
1) T_EJV_CREDIT_DS_INDEX
2) T_EJV_CREDIT_DS_INDEX_CONTRACT
I would like a SQL query like below as a LINQ expression
SELECT MAX(INDEX_FAMILY_VERSION) FROM T_EJV_CREDIT_DS_INDEX cdi
INNER JOIN T_EJV_CREDIT_DS_INDEX_CONTRACT cdic
ON cdic.INDEX_ID = cdi.INDEX_ID
WHERE cdi.INDEX_SHORT_NAME LIKE '%#VARIABLE1%'
AND cdic.TENOR = #VARIABLE2
This is what I have attempted so far
var maxFamilyVersion = (from ic in dsIndexContract
join i in dsIndex on i.INDEX_ID equals ic.INDEX_ID
where i.INDEX_SHORT_NAME.CONTAINS(strindex) && ic.TENOR equals d.TERM
select new
{
ic.INDEX_FAMILY_VERSION.Max()
}).Take(1).ToList();
But the above mentioned starts showing compile issues with the syantax as shown below
Checking for equality in your where condition can be done with ==. The keyword equals is only used in a join condition.
var result = (from ic in dsIndexContract
join i in dsIndex on i.INDEX_ID equals ic.INDEX_ID
where i.INDEX_SHORT_NAME.CONTAINS(strindex) && ic.TENOR == d.TERM
select new
{
ic.INDEX_FAMILY_VERSION.Max()
}).FirstOrDefault();
And instead of .Take(1).ToList(), you can use .FirstOrDefault() to retrieve the first item.
Or a more efficient way is to use .Max() directly instead of .FirstOrDefault():
var result = (from ic in dsIndexContract
join i in dsIndex on i.INDEX_ID equals ic.INDEX_ID
where i.INDEX_SHORT_NAME.CONTAINS(strindex) && ic.TENOR == d.TERM
select ic.INDEX_FAMILY_VERSION).Max();
This should do it:
var maxFamilyVersion =
(from ic in dsIndexContract
join i in dsIndex on ic.INDEX_ID equals i.INDEX_ID
where i.INDEX_SHORT_NAME.CONTAINS(strindex) && ic.TENOR == d.TERM
select ic.INDEX_FAMILY_VERSION).Max();
I have the following two LINQ queries:
public int getJobsCount()
{
var numJobs =
(from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id
select j).Count();
return numJobs;
}
public List<Job> getJobs()
{
var jobs =
(
from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id
orderby j.issueDatetime descending
select new Job { x = j.field, y = c.field, etc }
).Skip(startJob - 1).Take(numJobs);
return jobs;
}
There's a lot of duplicate code in there - the "from", and "join" lines are identical, and I'll be adding in some "where" lines as well that will also be identical.
I tried adding a method that returned an IQueryable for the first part:
public IQueryable getJobsQuery()
{
var q =
from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id;
return q;
}
...but I get "a query body must end with a select clause or a group clause".
If I add a select clause on to the end off that function, I can't call count() on the result:
// getJobsQuery:
var q = from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id
select new { a = j.y, b = c.z }
// another method:
var q = getJobsQuery();
var numJobs = q.Count(); // "IQueryable doesn't contain a definition for count"
Is there a way to build up this query step-by-step to avoid duplicating a whole lot of code?
There are two ways of writing LINQ-queries, and though it doesn't really matter witch one you use it's good to know both of them cause they might learn you something about how LINQ works.
For instance, you have a set of jobs. If you were to select all jobs with an industryId of 5 (wild guess of data-types) you'd probably write something like this:
from j in dbConnection.jobs
where j.inustryId == 5
select j;
The very same query can also be written like this
dbConnections.jobs.Where(j => j.industryId == 5);
Now, I'm not here to preach saying one way is better than the other, but here you can clearly see how LINQ using the extension-methods syntax automatically selects on the iterated object (unless you do a select), whereas in the query-syntax you must do this explicitly. Also, if you were to add inn another where clause here it would look something like this:
from j in dbConnection.jobs
where j.inustryId == 5 // not using && here just to prove a point
where j.cityId == 3 // I THINK this is valid syntax, I don't really use the query-syntax in linq
select j;
While in the extension-methods you can just append more method-calls like so:
dbConnections.jobs.Where(j => j.industryId == 5)
.Where(j => j.cityId == 3);
Now this is good to know cause this means you can just put your linq-query inside a function an continue querying it. And all you need to do to make it work in your case is just explicitly select the starting variable j, or all the variables you need like so:
var q =
from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id;
select new {j = j, i = i, c = c, s = s, pt = pt };
return q;
Then you should be able to do for instance this:
getJobsQuery().Where(a => a.i.id == 5); // I used a as a name for "all", like the collection of variables
or using the query-syntax
from a in getJobsQuery()
where a.i.id == 5
select a;
Would this be better solved by returning a set of data (e.g. the common data) and querying for a subset of that data?
E.g. [pseudocode]
var allJobs =
(from j in dbConnection.jobs
join i in dbConnection.industries on j.industryId equals i.id
join c in dbConnection.cities on j.cityId equals c.id
join s in dbConnection.states on j.stateId equals s.id
join pt in dbConnection.positionTypes on j.positionTypeId equals pt.id
select j);
var myJobs = allJobs.OrderBy(j => j.issuedate).skip(expr).Take(allJobs.Count);
or similar...
I have a beginners LINQ2SQL question. I have this huge (but not complex) SQL statement:
SELECT Artikel.ArtikelID,
Artikel.CategorieID,
Artikel.ImageFile,
Artikel.RetailPrijs,
ISNULL(ShopArtikel.VerkoopsPrijs, Artikel.VerkoopsPrijs) AS VerkoopsPrijs,
Artikel.ArtikelCode,
Artikel.InAssortimentSinds,
ArtikelTaal.ArtikelNaam,
ArtikelTaal.ArtikelOmschrijving
FROM Artikel
INNER JOIN ArtikelTaal ON Artikel.ArtikelID = ArtikelTaal.ArtikelID
INNER JOIN ShopArtikel ON Artikel.ArtikelID = ShopArtikel.ArtikelID
INNER JOIN Categorie ON Artikel.CategorieID = Categorie.CategorieID
INNER JOIN CategorieTaal ON Categorie.CategorieID = CategorieTaal.CategorieID
INNER JOIN Shop ON ShopArtikel.ShopId = Shop.ShopID
INNER JOIN CategorieGroepShop ON Shop.ShopID = CategorieGroepShop.ShopId
INNER JOIN Taal ON ArtikelTaal.TaalCode = Taal.TaalCode AND CategorieTaal.TaalCode = Taal.TaalCode
INNER JOIN CategorieGroepTaal ON Taal.TaalCode = CategorieGroepTaal.TaalCode AND CategorieGroepShop.CategorieGroepId = CategorieGroepTaal.CategorieGroepID
INNER JOIN CategorieGroep ON Categorie.CategorieGroepID = CategorieGroep.CategorieGroepID AND CategorieGroepTaal.CategorieGroepID = CategorieGroep.CategorieGroepID AND CategorieGroepShop.CategorieGroepId = CategorieGroep.CategorieGroepID
WHERE (Shop.ShopID = 23) AND
(Taal.TaalCode = 'dut') AND
(Artikel.Onzichtbaar = 0) AND
(Artikel.NietBestelbaar = 0) AND
(Categorie.Onzichtbaar = 0) AND
(Artikel.Voorraad >= Artikel.LevertijdDrempel)
and I am converting this to LINQ and have this:
var allProducts = from artikelen in dc.Artikels
join sa in dc.ShopArtikels on artikelen.ArtikelID equals sa.ArtikelID
join at in dc.ArtikelTaals on artikelen.ArtikelID equals at.ArtikelID
join cat in dc.Categories on artikelen.CategorieID equals cat.CategorieID
join catt in dc.CategorieTaals on cat.CategorieID equals catt.CategorieID
join catg in dc.CategorieGroeps on cat.CategorieGroepID equals catg.CategorieGroepID
join catgt in dc.CategorieGroepTaals on catg.CategorieGroepID equals catgt.CategorieGroepID
join sh in dc.Shops on sa.ShopId equals sh.ShopID
join catgs in dc.CategorieGroepShops on sh.ShopID equals catgs.ShopId
join tl in dc.Taals on new { tc1 = at.TaalCode, tc2 = catgt.TaalCode } equals new { tc1 = tl.TaalCode, tc2 = tl.TaalCode }
where sh.ShopID == shop.BLL.Business.ShopController.CurrentShop.Id
select dc.Artikels;
but I have the idea that I made some (minor) mistakes while joining.
any ideas please!
EDIT
I have rewritten the LINQ query to this:
var allProducts = from artikelen in dc.Artikels
join at in dc.ArtikelTaals on artikelen.ArtikelID equals at.ArtikelID
join sa in dc.ShopArtikels on artikelen.ArtikelID equals sa.ArtikelID
join cat in dc.Categories on artikelen.CategorieID equals cat.CategorieID
join catt in dc.CategorieTaals on cat.CategorieID equals catt.CategorieID
join sh in dc.Shops on sa.ShopId equals sh.ShopID
join catgs in dc.CategorieGroepShops on sh.ShopID equals catgs.ShopId
join tl in dc.Taals on new { tc1 = at.TaalCode, tc2 = catt.TaalCode } equals new { tc1 = tl.TaalCode, tc2 = tl.TaalCode }
join catgt in dc.CategorieGroepTaals on new { tl.TaalCode, catgs.CategorieGroepId } equals new { catgt.TaalCode, catgt.CategorieGroepID }
join catg in dc.CategorieGroeps on new { cat.CategorieGroepID, catgt.CategorieGroepID, catgs.CategorieGroepId } equals new { catg.CategorieGroepID, catg.CategorieGroepID, catg.CategorieGroepID }
where sh.ShopID == 230
select dc.Artikels;
but I have a syntax error after "dut" }
Edit 2:
changed the join and replaced "dut" with the corresponding field in the database.
still have the error after the first }
it says: type inference failed in the call to 'Join'
Some of the SQL joins have multiple join conditions, which you didn't put in the LINQ query.
If this is something that will be frequently run then you should rewrite it as a stored procedure. I believe it is too convoluted and complex for a LINQ statement - too hard to see what's going on.
There is a tool for it, but I didn't try it. May be it's usefull for you.
http://www.sqltolinq.com/
It looks like the error line is actually a "Where" cause but not "Joining".
You can actually split the whole long Linq statement into smaller Query.
so for this case, its better to split it like this:
var at = from a in dc.ArtikelTaals
where a.TaalCode == "dut"
select a;
var catt = from c in dc.CategorieTaals
where c.TaalCode == "dut"
select c;
.....
and you can join the IQueryable "at" and "catt" in your complex query later.
SQL:
SELECT
u.id,
u.name,
isnull(MAX(h.dateCol), '1900-01-01') dateColWithDefault
FROM universe u
LEFT JOIN history h
ON u.id=h.id
AND h.dateCol<GETDATE()-1
GROUP BY u.Id, u.name
A solution, albeit one that defers handling of the null value to the code, could be:
DateTime yesterday = DateTime.Now.Date.AddDays(-1);
var collection=
from u in db.Universe
select new
{
u.id,
u.name,
MaxDate =(DateTime?)
(
from h in db.History
where u.Id == h.Id
&& h.dateCol < yesterday
select h.dateCol
).Max()
};
This does not produce exactly the same SQL, but does provide the same logical result. Translating "complex" SQL queries to LINQ is not always straightforward.
var collection=
from u in db.Universe
select new
{
u.id,
u.name,
MaxDate =(DateTime?)
(
from h in db.History
where u.Id == h.Id
&& h.dateCol < yesterday
select h.dateCol
).Max()
};
Just youse the above code and this should work fine!
You're going to want to use the join into construct to create a group query.
TestContext db = new TestContext(CreateSparqlTripleStore());
var q = from a in db.Album
join t in db.Track on a.Name equals t.AlbumName into tracks
select new Album{Name = a.Name, Tracks = tracks};
foreach(var album in q){
Console.WriteLine(album.Name);
foreach (Track track in album.Tracks)
{
Console.WriteLine(track.Title);
}
}
This isn't a full answer for you, but on the left join piece you can use the DefaultIfEmpty operator like so:
var collection =
from u in db.Universe
join history in db.History on u.id = history.id into temp
from h in temp.DefaultIfEmpty()
where h.dateCol < DateTime.Now.Date.AddDays(-1)
select u.id, u.name, h.dateCol ?? '1900-01-01'
I haven't had the need to do any groupby commands yet, so I left that out as to not send you down the wrong path. Two other quick things to note. I have been unable to actually join on two parameters although as above there are ways to get around it. Also, the ?? operator works really well in place of the isnull in SQL.