I am using below code to join two tables based on officeId field. Its retuning 0 records.
IQueryable<Usage> usages = this.context.Usage;
usages = usages.Where(usage => usage.OfficeId == officeId);
var agencyList = this.context.Agencies.ToList();
var usage = usages.ToList();
var query = usage.Join(agencyList,
r => r.OfficeId,
a => a.OfficeId,
(r, a) => new UsageAgencyApiModel () {
Id = r.Id,
Product = r.Product,
Chain = a.Chain,
Name = a.Name
}).ToList();
I have 1000+ records in agencies table and 26 records in usage table.
I am expecting 26 records as a result with chain and name colums attached to result from agency table.
Its not returning anything. I am new to .net please guide me if I am missing anything
EDIT
#Tim Schmelter's solution works fine if I get both table context while executing join. But I need to add filter on top of usage table before applying join
IQueryable<Usage> usages = this.context.Usage;
usages = usages.Where(usage => usage.OfficeId == officeId);
var query = from a in usages
// works with this.context.usages instead of usages
join u in this.context.Agencies on a.OfficeId equals u.OfficeId
select new
{
Id = a.Id,
Product = a.Product,
Chain = u.Chain,
Name = u.Name
};
return query.ToList();
Attaching screenshot here
same join query works fine with in memory data as you see below
Both ways works fine if I add in memory datasource or both datasource directly. But not working if I add filter on usages based on officeId before applying join query
One problem ist that you load all into memory first(ToList()).
With joins i prefer query syntax, it is less verbose:
var query = from a in this.context.Agencies
join u in this.context.Usage on a.OfficeId equals u.OfficeId
select new UsageAgencyApiModel()
{
Id = u.Id,
Product = u.Product,
Chain = a.Chain,
Name = a.Name
};
List<UsageAgencyApiModel> resultList = query.ToList();
Edit: You should be able to apply the Where after the Join. If you still don't get records there are no matching:
var query = from a in this.context.Agencies
join u in this.context.Usage on a.OfficeId equals u.OfficeId
where u.OfficeId == officeId
select new UsageAgencyApiModel{ ... };
The following code can help to get the output based on the ID value.
Of course, I wrote with Lambda.
var officeId = 1;
var query = context.Agencies // your starting point - table in the "from" statement
.Join(database.context.Usage, // the source table of the inner join
agency => agency.OfficeId, // Select the primary key (the first part of the "on" clause in an sql "join" statement)
usage => usage.OfficeId , // Select the foreign key (the second part of the "on" clause)
(agency, usage) => new {Agency = agency, Usage = usage }) // selection
.Where(x => x.Agency.OfficeId == id); // where statement
Related
I have this Join :
var mycust= db.CUSTOMER.Where(x => x.NAME.Contains(nameid)).ToList();
var CancCustomer = (from cust in myCust
join ip in db.IPS on must.ID equals ip.CUSTOMER_ID
select new JoinObj {ID = cust.ID, NAME = cust.NAME, LASTNAME = cust.LASTNAME,
TYPE_ID = ip.TYPE_ID, TYPE2_ID = ip.TYPE2_ID,
SERVICE_ID = ip.SERVICE_ID , REASON = ip.REASON }).ToList();
This code returns the first linq result multiple times? What am I missing? Thanks.
Instead of Where, you should use SingleOrDefault/Single - these would indeed return a single row into your mycust variable.
SingleOrDefault would put a null into the variable if no such customers were found (and assuming a Customer is a reference type - if it were a value type, it would be the default value for the type). Single would throw an exception if no items were found or more than one were found, which could be very useful in finding errors in your data (such as duplicate customer records).
Additionally, it is likely your ip table has multiple matching records for a customer - which is why you would be seeing multiple records being returned from your select.
You have multiple Duplicate Record received Then Try For following quires
var mycust= db.CUSTOMER.Where(x => x.NAME.Contains(nameid)).ToList();
var CancCustomer = (from cust in myCust
join ip in db.IPS on cust.ID equals ip.CUSTOMER_ID
select new JoinObj {ID = cust.ID, NAME = cust.NAME, ASTNAME=cust.LASTNAME, TYPE_ID = ip.TYPE_ID, TYPE2_ID = ip.TYPE2_ID, SERVICE_ID = ip.SERVICE_ID , REASON = ip.REASON }).distinct().ToList();
Other Wise Multiple record then You Get One Record for You following Query
var mycust= db.CUSTOMER.Where(x => x.NAME.Contains(nameid)).ToList();
var CancCustomer = (from cust in myCust
join ip in db.IPS on must.ID equals ip.CUSTOMER_ID
select new JoinObj {ID = cust.ID, NAME = cust.NAME, LASTNAME = cust.LASTNAME, TYPE_ID = ip.TYPE_ID, TYPE2_ID = ip.TYPE2_ID, SERVICE_ID = ip.SERVICE_ID , REASON = ip.REASON }).distinct().FirstOrDefault();
I need help with a search method for searching the tables for a matching text.
This works, except that the join needs to be LEFT OUTER JOIN otherwise I dont get any results if the pageId is missing in any of the tables.
This solution takes to long time to run, I would appreciate if someone can help me out with a better solution to handle this task.
public async Task<IEnumerable<Result>> Search(string query)
{
var temp = await (from page in _context.Pages
join pageLocation in _context.PageLocations on page.Id equals pageLocation.PageId
join location in _context.Locations on pageLocation.LocationId equals location.Id
join pageSpecialty in _context.PageSpecialties on page.Id equals pageSpecialty.PageId
join specialty in _context.Specialties on pageSpecialty.SpecialtyId equals specialty.Id
where
page.Name.ToLower().Contains(query)
|| location.Name.ToLower().Contains(query)
|| specialty.Name.ToLower().Contains(query)
select new Result
{
PageId = page.Id,
Name = page.Name,
Presentation = page.Presentation,
Rating = page.Rating
}).ToListAsync();
var results = new List<Result>();
foreach (var t in temp)
{
if (!results.Exists(p => p.PageId == t.PageId))
{
t.Locations = GetLocations(t.PageId);
t.Specialties = GetSpecialties(t.PageId);
results.Add(t);
}
}
return results;
}
Using navigation properties, the query could look like:
var temp = await (from page in _context.Pages
where Name.Contains(query)
|| page.PageLocation.Any(pl => pl.Location.Name.Contains(query))
|| page.PageSpecialties.Any(pl => pl.Specialty.Name.Contains(query))
select new Result
{
PageId = page.Id,
Name = page.Name,
Presentation = page.Presentation,
Rating = page.Rating,
Locations = page.PageLocation.Select(pl => pl.Location),
Specialties = page.PageSpecialties.Select(pl => pl.Specialty)
}).ToListAsync();
This has several benefits:
By the absence of joins, The query returns unique Result objects right away, so you don't need to deduplicate them afterwards.
The locations and specialties are loaded in the same query instead of two queries per Result (aka n+1 problem).
(Likely) ToLower is removed because the search is probably not case sensitive anyway. The query is executed as SQL and most of the times, SQL databases have case-insensitive collations. Removing ToLower makes the query sargable again.
I have two tables. Table One contains a list of Areas, and Table Two contains a list of Samples, with each Sample row containing Area_ID as a Foreign Key.
I need to retrieve all the records in my Area table with only the most recent corresponding Sample Status. I have this query, but it just returns one Area with the most recent sample from the Sample table:
var result = (
from a in db.area
join c in db.sample
on a.location_id equals c.location_id
select new
{
name = a.location_name,
status = c.sample_status,
date = c.sample_date
}).OrderByDescending(c => c.date).FirstOrDefault();
A solution could be filtering your second DbSet:
var result = from a in db.area
join c in db.sample.Where(s=>s.location_id==a.location_id).OrderByDescending(c => c.sample_date).Take(1)
on a.location_id equals c.location_id
select new
{
name = a.location_name,
status = c.sample_status,
date = c.sample_date
};
Another solution could be applying a group join:
var result = from a in db.area
join c in db.sample
on a.location_id equals c.location_id into samples
let sample=samples.OrderByDescending(c => c.sample_date).FirstOrDefault()
select new
{
name = a.location_name,
status = sample.sample_status,
date = sample.sample_date
};
If you use navigation properties could be even easier. Supposing you have a one to many relationship between Area and Sample:
var result =from a in db.area
let sample= a.Samples.OrderByDescending(c => c.sample_date).FirstOrDefault()
select new
{
name = a.location_name,
status = sample.sample_status,
date = sample.sample_date
};
I am attempting to write the following SQL as a linq query.
SELECT grp.OrganisationId,
grp.OrderCount,
organisations.Name
FROM (select OrganisationId,
count(*) as OrderCount
from orders
where 1 = 1
group by OrganisationId) grp
LEFT OUTER JOIN organisations on grp.OrganisationId = organisations.OrganisationId
WHERE 1 = 1
The where clauses are simplified for the benefit of the example.
I need to do this without the use of navigational properties.
This is my attempt:
var organisationQuery = ClientDBContext.Organisations.Where(x => true);
var orderGrouped = from order in ClientDBContext.Orders.Where(x => true)
group order by order.OrganisationId into grouping
select new { Id = grouping.Key.Value, OrderCount = grouping.Count() };
var orders = from og in orderGrouped
join org in organisationQuery on og.Id equals org.Id
select(x => new OrganisationOrdersReportPoco()
{
OrganisationNameThenCode = org.Name,
TotalOrders = og.OrderCount
});
But I am getting an error of...
Type inference failed in the call to 'Join'
From previous threads, I believe this is because I have "lost the join with order" (but I don't understand why that matters when I am creating a new recordset of Organisation, Count).
Thanks!
I understand you may believe navigation properties are the solution here, but if possible, please can we keep the discussion to the join off of the group by as this is the question I am trying to resolve.
You are mixing lambda and LINQ expressions. Change select to:
select new OrganisationOrdersReportPoco()
{
OrganisationNameThenCode = org.Name,
TotalOrders = og.OrderCount
};
If i understood your model correctly you could try this instead:
var orders = ClientDBContext.Organisations.Select(org => new OrganisationOrdersReportPoco
{
OrganisationNameThenCode = org.Name,
TotalOrders = org.Orders.Count()
}).ToList();
I am getting the following error on the word "join" in the code below.
The type of one of the expressions in the join clause is incorrect.
Type inference failed in the call to 'Join'.
var organisationQuery = ClientDBContext.Organisations.Where(x => true);
var orderGrouped = from order in ClientDBContext.Orders.Where(x => true)
group order by order.OrganisationId into grouping
select new { Id = grouping.Key.Value, OrderCount = grouping.Count() };
var orders = from og in orderGrouped
join org in organisationQuery on og.Id equals org.Id
select(x => new OrganisationOrdersReportPoco()
{
OrganisationNameThenCode = org.Name,
TotalOrders = og.OrderCount
});
I don't see a problem with the join clause? Can anyone please advise?
Edit:
This is the piece of SQL I am attempting to write as LINQ.
SELECT grp.OrganisationId,
grp.OrderCount,
organisations.Name
FROM (select OrganisationId,
count(*) as OrderCount
from orders where 1 = 1 group by OrganisationId) grp
LEFT OUTER JOIN organisations on grp.OrganisationId = organisations.OrganisationId
WHERE 1 = 1
I have complicated where clauses on both orders and organisations... simplified for this example.
You are selecting into an anonymous type in the first query:
var orderGrouped = ..
select new { Id = grouping.Key.Value, OrderCount = grouping.Count() };
This 'breaks' the connection with order.
The join looks like it should work for Linq-to-Objects but it can't be converted into SQL.
You'll have to eliminate the anonymous type and somehow make a more direct connection.
I wonder why you don't simply go from Organisations? With a proper mapping using nav-properties it should look like:
from org in ClientDBContext.Organisations
select(x => new OrganisationOrdersReportPoco()
{
OrganisationNameThenCode = org.Name,
TotalOrders = org.Orders.Count
};
using the Id properties should be a little more involved but follow the same pattern.
(Credit to Giorgi Nakeuri)
I was confusing LAMBDA with LINQ expressions.
Replacing my select with this solved it.
select new OrganisationOrdersReportPoco()
{
OrganisationNameThenCode = org.Name,
TotalOrders = og.OrderCount
};