if (rowCount == 1)
{
query =
(from x in partJoinTableRepository.GetPartJoinQuery()
join y in partRepository.GetPartsQuery() on x.PartId equals y.Id
join z in partProductTypeReposiotry.GetPartProductTypesQuery() on x.PartId equals z.PartId
where y.IsSkipped == 0 && (y.IsDisabled != "Y" || y.IsDisabled == null) && z.CreatedDate == x.CreatedDate
&& x.CreatedDate == Convert.ToDateTime(fromDate) && cpaclassids.Contains(x.ProductTypeId.ToString())
select x).Cast<PartJoinTable>().AsQueryable();
predicate = PredicateBuilder.True(query);
}
else
{
query = query.Join(partJoinTableRepository.GetPartJoinQuery(), "PartID", "PartID", "inner", "row1", null).Cast<PartJoinTable>().AsQueryable();
// predicate = PredicateBuilder.True(query);
} //query contains multiple dynamic inner joins
//repids contains the list ,I used the predicate builder for the linq to create AND Queries
foreach(var item in repids)
{
predicate = PredicateBuilder.True(query);
if (typeid == "3")
{
predicate = predicate.And(z => ids.Contains(z.ProductTypeId.ToString()) &&
z.CreatedDate == Convert.ToDateTime(fromDate));
}
}
var count = query.Where(predicate).Distinct().Count();
the above line is taking long time to execute,ids contains the lists and query contains the linq query.basically I need to form a multiple "AND" conditions
//The Query is taking lot of time to execute and multiple and conditions are not working
Remove ToList to improve performance. Because ToList execute your query and retrieve object list to memory. But you need only count. you don't need objects.
var count = query.Where(predicate).Distinct().Count();
If I understood you right, your problem is that this query has a long running time. Let's see your code in the last line:
var count = query.Where(predicate).Distinct().ToList().Count();
In LINQ to SQL (and to entities), your query doesn't execute thought you use ToList(), ToArray() etc.. For example, consider the following query:
var strings = Db.Table
.Where((string s) => s.Contains("A")) // Will convert to something like WHERE s LIKE '%A%'
.Select(s => s.ToUpper()) // Will convert to something like SELECT upper(s)
.ToList(); // Here the query sends to the DB and executes
The final query is SELECT upper(s) FROM [Table] WHERE s LIKE '%A%'.
In you case, first you send the query to the DB and get all the objects corresponding to the condition (.Where()), and then get their count inside your app.
Instead, if you'll get from the DB only the count, the query will be faster:
var count = query.Where(predicate).Distinct().Count(); // No .ToList()! Here, .Count() executes the query.
Related
I am trying to filter a flattened nested loop and filter from another list. So below is what I have been able to do. I tried this approach but when I run the query it does not save anything in the database. I need help to check and ignore existing records (same MemberId and Description) in the Tasklist table.
var addedtop = from a in db.TaskLists select new {a.MemberId,a.Description};
var membtasks = from m in members
from n in tasks
select new { m, n };
TaskList taskList = new TaskList();
foreach (var item in membtasks)
{
var exist = db.TaskLists.Where(a => a.Description == item.n && a.MemberId == item.m);
if(exist == null)
{
taskList .Description = item.n;
taskList .MemberId = item.m;
db.taskList .Add(taskList );
db.SaveChanges();
}
}
return Redirect(url);
The problem is exists will never be null. The line var exist = db.TaskLists.Where(a => a.Description == item.n && a.MemberId == item.m); returns an IQueryable that describes your query but hasn't actually executed against the database yet.
Try changing the line to:
var exist = db.TaskLists.Where(a => a.Description == item.n && a.MemberId == item.m).SingleOrDefault();
This executes the query and checks if there is a single item that satisfies your query. If there is no result at all the query returns null which will execute the code inside your if statement.
Your statement has not been executed query, you can change Where to Any like this:
var exist = db.TaskLists.Any(a => a.Description == item.n && a.MemberId == item.m);
Any function that returns data type is bool
I have two and more if conditions to inject my main query but if the condition has no value (is nullable) I don't want to inject to my query.
For example this is my AND query injection:
// first initialize query can have where or not
var query = context.QuestionInfoes.Include(x =>x.RelationsInfoes).AsQueryable();
// first if condition to inject query
if (filterQuestionInfo.ToProfileId.HasValue)
{
query = (from q in query
join qr in context.QuestionRelationsInfoes on q.Id equals qr.QuestionId
where q.BrodcastType == QuestionBrodcastType.All || filterQuestionInfo.ToProfileId == qr.ToProfileId
select q);
}
// second if condition to inject AND query and i want to this be OR injection
if (filterQuestionInfo.ProfileId.HasValue)
{
query = (from q in query
where q.ProfileId == filterQuestionInfo.ProfileId
select q);
}
Now I want to create "OR" injection and when I call .ToList(), I see just queries in SQL that I needed. In top example if ToProfileId and ProfileId have values, I see questions where sent to ToProfileId value and 0 questions from profile id in "ProfileId" value because second query is "And" condition to first query. But I want both of them when I fill both values.
when two values are null: I filtered all of questions (works now)
when one value of ToProfileId or ProfileId is null: I filtered all of questions on that value is not null (works now)
When both value are filled, I want both question list (does not work now)
Note: I don't want to create one query and inject all of my condition in to that query.
Assuming QuestionRelationsInfoes exists on QuestionInfoes as a navigation property called QuestionRelationsInfoes, then you dont need the join.
Unfortunately, you will have to construct the query based on the 3 scenarios (Both filters set, only 1st filter set, only 2nd filter set).
var query = context.QuestionInfoes.Include(x => x.RelationsInfoes);
if (filterQuestionInfo.ToProfileId.HasValue && filterQuestionInfo.ProfileId.HasValue)
{
query = query.Where(q =>
q.BrodcastType == QuestionBrodcastType.All ||
q.QuestionRelationsInfoes.ToProfileId == filterQuestionInfo.ToProfileId ||
q.ProfileId == filterQuestionInfo.ProfileId);
}
else if (filterQuestionInfo.ToProfileId.HasValue)
{
query = query.Where(q => q.BrodcastType == QuestionBrodcastType.All || filterQuestionInfo.ToProfileId == q.QuestionRelationsInfoes.ToProfileId);
}
else if (filterQuestionInfo.ProfileId.HasValue)
{
query = query.Where(q.ProfileId == filterQuestionInfo.ProfileId);
}
As an alternative, if you dislike the code repetition, you can push the check to SQL, by first checking if the filter is not null:
var query = context.QuestionInfoes.Include(x => x.RelationsInfoes);
if (filterQuestionInfo.ToProfileId.HasValue || filterQuestionInfo.ProfileId.HasValue)
{
query = query.Where(q =>
(filterQuestionInfo.ToProfileId.HasValue && (q.BrodcastType == QuestionBrodcastType.All || filterQuestionInfo.ToProfileId == q.QuestionRelationsInfoes.ToProfileId)) ||
(filterQuestionInfo.ProfileId.HasValue && q.ProfileId == filterQuestionInfo.ProfileId));
}
I'm completely new to LINQ, i want to rewrite some of mine SQL querys into LINQ (just to learn) and i'v already stuck at the beginning. Probably solution is very simple but as i'v said I'm completely new and i didn't find solution to this.
I have one query :
string typMoneta = textBox1.Text;
var moneta = from x in db.grupyTowarowes
where x.typ == typMoneta
select new
{
x.grupa
};
Which works ok and when i set
dataGridView1.DataSource = moneta;
Then i got output
And i want to use this output in my second query :
var query = from c in dbContext.Picking
where c.Number == 1000 && c.Group == moneta
select new
{
c.id
};
Problem is with c.Group == moneta. I don't know the correct syntax. Could someone help me?
I think you meant to use moneta.Contains(c.Group). In first query, make sure you use ToList() to load data into memory.
IList<string> moneta = (from x in db.grupyTowarowes
where x.typ == typMoneta
select x.grupa).ToList();
var query = (from c in dbContext.Picking
where c.Number == 1000 && moneta.Contains(c.Group)
select c.id).ToList();
The moneta is an IEnumerable<T> where T in your case is the type of grupa
That being said you should write your query like below:
var query = from c in dbContext.Picking
where c.Number == 1000
&& moneta.Contais(c.Group)
select new
{
c.id
};
or in fluent syntax like below:
var query = dbContext.Picking
.Where(pick => pick.Number == 1000
&& moneta.Contains(pick.Group))
.Select(pick => pick.id);
Note that moneta is not a collection of strings. It's a collection of objects that have a string property named "grupa".
Does this work for you?
var query =
from c in dbContext.Picking
where c.Number == 1000
&& moneta.Any(m => m.grupa == c.Group)
select new { c.id };
You could also do this:
// Get list of strings
var groups = moneta.Select(m => m.grupa).ToList();
// Get items where "Group" value is one of the strings in groups list, above.
var query =
from c in dbContext.Picking
where c.Number == 1000
&& groups.Contains(c.Group)
select new { c.id };
Using Entity Framework 6.0.2 and .NET 4.5.1 in Visual Studio 2013 Update 1 with a DbContext connected to SQL Server:
I have a long chain of filters I am applying to a query based on the caller's desired results. Everything was fine until I needed to add paging. Here's a glimpse:
IQueryable<ProviderWithDistance> results = (from pl in db.ProviderLocations
let distance = pl.Location.Geocode.Distance(_geo)
where pl.Location.Geocode.IsEmpty == false
where distance <= radius * 1609.344
orderby distance
select new ProviderWithDistance() { Provider = pl.Provider, Distance = Math.Round((double)(distance / 1609.344), 1) }).Distinct();
if (gender != null)
{
results = results.Where(p => p.Provider.Gender == (gender.ToUpper() == "M" ? Gender.Male : Gender.Female));
}
if (type != null)
{
int providerType;
if (int.TryParse(type, out providerType))
results = results.Where(p => p.Provider.ProviderType.Id == providerType);
}
if (newpatients != null && newpatients == true)
{
results = results.Where(p => p.Provider.ProviderLocations.Any(pl => pl.AcceptingNewPatients == null || pl.AcceptingNewPatients == AcceptingNewPatients.Yes));
}
if (string.IsNullOrEmpty(specialties) == false)
{
List<int> _ids = specialties.Split(',').Select(int.Parse).ToList();
results = results.Where(p => p.Provider.Specialties.Any(x => _ids.Contains(x.Id)));
}
if (string.IsNullOrEmpty(degrees) == false)
{
List<int> _ids = specialties.Split(',').Select(int.Parse).ToList();
results = results.Where(p => p.Provider.Degrees.Any(x => _ids.Contains(x.Id)));
}
if (string.IsNullOrEmpty(languages) == false)
{
List<int> _ids = specialties.Split(',').Select(int.Parse).ToList();
results = results.Where(p => p.Provider.Languages.Any(x => _ids.Contains(x.Id)));
}
if (string.IsNullOrEmpty(keyword) == false)
{
results = results.Where(p =>
(p.Provider.FirstName + " " + p.Provider.LastName).Contains(keyword));
}
Here's the paging I added to the bottom (skip and max are just int parameters):
if (skip > 0)
results = results.Skip(skip);
results = results.Take(max);
return new ProviderWithDistanceDto { Locations = results.AsEnumerable() };
Now for my question(s):
As you can see, I am doing an orderby in the initial LINQ query, so why is it complaining that I need to do an OrderBy before doing a Skip (I thought I was?)...
I was under the assumption that it won't be turned into a SQL query and executed until I enumerate the results, which is why I wait until the last line to return the results AsEnumerable(). Is that the correct approach?
If I have to enumerate the results before doing Skip and Take how will that affect performance? Obviously I'd like to have SQL Server do the heavy lifting and return only the requested results. Or does it not matter (or have I got it wrong)?
I am doing an orderby in the initial LINQ query, so why is it complaining that I need to do an OrderBy before doing a Skip (I thought I was?)
Your result starts off correctly as an ordered queryable: the type returned from the query on the first line is IOrderedQueryable<ProviderWithDistance>, because you have an order by clause. However, adding a Where on top of it makes your query an ordinary IQueryable<ProviderWithDistance> again, causing the problem that you see down the road. Logically, that's the same thing, but the structure of the query definition in memory implies otherwise.
To fix this, remove the order by in the original query, and add it right before you are ready for the paging, like this:
...
if (string.IsNullOrEmpty(languages) == false)
...
if (string.IsNullOrEmpty(keyword) == false)
...
result = result.OrderBy(r => r.distance);
As long as ordering is the last operation, this should fix the runtime problem.
I was under the assumption that it won't be turned into a SQL query and executed until I enumerate the results, which is why I wait until the last line to return the results AsEnumerable(). Is that the correct approach?
Yes, that is the correct approach. You want your RDBMS to do as much work as possible, because doing paging in memory defeats the purpose of paging in the first place.
If I have to enumerate the results before doing Skip and Take how will that affect performance?
It would kill the performance, because your system would need to move around a lot more data than it did before you added paging.
How can I write this SQL statement using C# and LINQ? I am quering an Oracle database and the table has multiple revisions of the records. Therefore, I want onyl the current revision of each record contained in the table.
The SQL looks like this:
select TP_ID, TP_TEXT, TP_DEFN_SAKEY
from TP_DEFN tp1
where tp1.TP_ACTIVE_FLAG = 'Y' and
tp1.FAMILY_ID = 1 and
tp1.TP_DEFN_REV_DTS = (select max(TP_DEFN_REV_DTS)
from TP_DEFN tp2
where tp2.family_id = tp1.family_id and tp2.tp_id = tp1.tp_id )
order by TP_ID
TP_DEFN_REV_DTS is the date time field that stores the current revision.
I am a beginner with LINQ and have been struggling to find an workable solution. Every time that I try grouping in the LINQ query I get an error
GroupBy is not supported
Try something like this:
var res =
from tp1 in TP_DEFN
where tp1.TP_ACTIVE_FLAG == "Y" &&
tp1.FAMILY_ID == 1 &&
tp1.TP_DEFN_REV_DTS == (from tp2 in TP_DEFN
where tp2.FAMILY_ID == tp1.FAMILY_ID &&
tp2.TP_ID == tp1.TP_ID
select tp2.TP_DEFN_REV_DTS).Max()
orderby tp1.TP_ID
select new
{
tp1.TP_ID,
tp1.TP_TEXT,
tp1.TP_DEFN_SAKEY
};
Off the top of my head, and not knowing which LINQ provider you're using...
var q = from tp1 in Context.TP_DEFN
where tp1.TP_ACTIVE_FLAG == "Y"
&& tp1.FAMILY_ID == 1
&& tp1.TP_DEFN_REV_DTS
== Context.TP_DEFN.Where(tp2 => tp2.FAMILY_ID == tp1.FAMILY_ID
&& tp2.TP_ID == tp1.TP_ID)
.Max(tp2 => tp2.TP_DEFN_REV_DTS)
orderby tp1.TP_ID
select new
{
tp1.TP_ID,
tp1.TP_TEXT,
tp1.TP_DEFN_SAKEY
};
If you're using entity framework or linq-to-sql, you can just pass the direct sql if you want (although that'll prevent change tracking, at least by default).
For EF, use ObjectContext.ExecuteStoreQuery: http://msdn.microsoft.com/en-us/library/dd487208.aspx
For L2S, use DataContext.ExecuteQuery: http://msdn.microsoft.com/en-us/library/system.data.linq.datacontext.executequery.aspx