This is my tag table:
post_id tag topic
1 picture entertainment
1 camera entertainment
1 mobile technology
2 cable technology
This is my SQL right now (Using Zend Framework):
$select = $db->select();
$select->from(array('t' => 'tags'), array('count(*)', 't.topic'))
->joinInner(array('p' => 'posts'),'p.post_id = t.post_id')
->where('p.status = ?', self::STATUS_LIVE)
->where('t.topic= ?', $options);
return $db->fetchOne($select);
I want to count topics, selecting just one per id. In this case it will be:
entertainment: 1
technology: 2
My result right now is:
entertainment: 2
technology: 2
This is the solution:
$select = $db->select();
$select->from(array('t' => new Zend_Db_Expr('(SELECT post_id,topic FROM tags group by post_id,topic)')), array('count(*)', 't.topic'))
->joinInner(array('p' => 'posts'), 'p.post_id = t.post_id', array())
->where('p.status = ?', self::STATUS_LIVE)
->where('t.topic= ?', $options)
->group("t.topic");
return $db->fetchOne($select);
You can use this query :
SELECT COUNT(*),topic FROM (SELECT post_id,topic FROM tags GROUP BY post_id,topic) t GROUP BY topic;
Same query in zend :
$select = $db->select();
$select->from(array('t' => new Zend_Db_Expr('(SELECT post_id,topic FROM tags group by post_id,topic)')), array('count(*)', 't.topic'))
->group("t.topic");
$db->fetchAll($select);
Related
I am using a LinqToSql-DataSource for a GridView in this way:
wsv.wsv2DataContext db = new wsv.wsv2DataContext();
e.KeyExpression = "id";
e.QueryableSource = (from mitgliedschaft in db.mitgliedschaft
join person in db.person on mitgliedschaft.person_id equals person.id
join institution in db.institution on mitgliedschaft.verein_id equals institution.id
select new
{
vorname = person.vorname,
nachname = person.nachname,
nameVerein = institution.name,
vereinid = mitgliedschaft.verein_id,
id = mitgliedschaft.id,
verbandsMitgliedsNummer = person.verbandsMitgliedsNummer,
strasse = person.strasse,
plz = person.plz,
ort = person.ort,
geburtsdatum = person.geburtsdatum,
geschlechtid = person.geschlechtid,
statusid = mitgliedschaft.statusid,
bezirk_id = mitgliedschaft.bezirk_id,
kreis_id = mitgliedschaft.kreis_id,
person_id = mitgliedschaft.person_id.Value,
deletedFlag = mitgliedschaft.deletedFlag,
stammverein = mitgliedschaft.stammVerein,
eintrittsdatum = mitgliedschaft.eintritt
}).GroupBy(p => p.person_id).Select(p => p.First());
}
Now i want to order the Selection. At first the "stammVerein"-Column of Table "mitgliedschaft" descending AND the Column "eintritt" of Table "mitgliedschaft". I have tried several ways:
wsv.wsv2DataContext db = new wsv.wsv2DataContext();
e.KeyExpression = "id";
e.QueryableSource = (from mitgliedschaft in db.mitgliedschaft
join person in db.person on mitgliedschaft.person_id equals person.id
join institution in db.institution on mitgliedschaft.verein_id equals institution.id
orderby mitgliedschaft.stammVerein descending, mitgliedschaft.eintritt
select new
{
...
}).GroupBy(p => p.person_id).Select(p => p.First());
}
AND:
wsv.wsv2DataContext db = new wsv.wsv2DataContext();
e.KeyExpression = "id";
e.QueryableSource = (from mitgliedschaft in db.mitgliedschaft
join person in db.person on mitgliedschaft.person_id equals person.id
join institution in db.institution on mitgliedschaft.verein_id equals institution.id
select new
{
...
}).GroupBy(p => p.person_id).Select(p => p.First()).OrderByDescending(stamm => stamm.stammverein).ThenBy(eintritt => eintritt.eintrittsdatum);
}
AND:
wsv.wsv2DataContext db = new wsv.wsv2DataContext();
e.KeyExpression = "id";
e.QueryableSource = (from mitgliedschaft in db.mitgliedschaft
join person in db.person on mitgliedschaft.person_id equals person.id
join institution in db.institution on mitgliedschaft.verein_id equals institution.id
select new
{
....
}).OrderByDescending(stamm => stamm.stammverein).ThenBy(eintritt => eintritt.eintrittsdatum).GroupBy(p => p.person_id).Select(p => p.First());
But nothing of this has any Effects ! I am very new in this kind of DataSource and Linq.
Can anyone help me achieving this order ?
Items within a grouped result will not retain their order. Depending on how you want to factor in the ordering, you will need to do it after the group by, and before, and/or after your First...
To accomplish this, it will be easiest if you map the relationships in EF with navigation properties rather than substituting SQL with Linq QL (joins and such)
Using the following base query:
var query = db.mitgliedschaft
.GroupBy(m => m.Person); // Group by related entity, not ID
For instance, after the group by, you will have sets of records grouped by Person. If you want the first Person with an earliest related record:
var result = query.OrderByDescending(g => g.Key.mitgliedschafts.Max(stamm => stamm.stammverein)
.ThenBy(stamm => stamm.eintritt.eintrittsdatum)
.First();
This is taking a wild guess at your schema & entity relationships, but hopefully it will help you work out something that fits. I can only guess at what eintritt is and how it relates to your entity model.
The initial query takes just your base entities that you want to group, and groups them by the related entity. The result of that grouping will be a set of Grouped mitgliedschafts with a key being the Person. To Order those groups by the person with the most recent mitgliedschafts we use an orderby on the Key's associated mitgliedschafts using the Max value for the collection given a descending order request.
The First then gives us the first grouped collection of mitgliedschafts.
Then if you want to sort the resulting list of mitgliedschafts after getting the person with the most recent one:
var result = query.OrderByDescending(g => g.Key.mitgliedschafts.Max(stamm => stamm.stammverein)
.ThenBy(stamm => stamm.eintritt.eintrittsdatum)
.First().OrderByDescending(stamm => stamm.stammverein)
.ThenBy(stamm => stamm.eintritt.eintrittsdatum)
.ToList();
The 2nd set of OrderBy clauses apply to the selected group, or the mitgliedschafts.
To compose the desired view model, Insert a Select() to build the view model from the mitgliedschafts before the ToList().
With the navigation properties this can probably be done without resorting to a group by. On a hunch, something like this should return something similar:
var query = db.Person
.OrderByDescending(p => p.mitgliedschafts.Max(stamm => stamm.stammverien))
.ThenBy(stamm => stamm.eintritt.eintrittsdatum)
.SelectMany(p => p.mitgliedschafts)
.OrderByDescending(stamm => stamm.stammverien)
.ThenBy(stamm => stamm.eintritt.eintrittsdatum)
.Select(stamm => new { ... })
.ToList();
Anyhow, hopefully that gives you some ideas on things to try if you have the navigation properties mapped or can set those up.
I have a main VendorProfile table and a 1-many VendorHistory table that contains status codes and date stamps. The query below works at retrieving only the latest status (status code and date) for each vendor. However, the view allows the user to select checkboxes of any of the status codes to filter the view. So I need to add a where clause that matches ANY of the checkbox StatusSelections.
Model Diagram
public IEnumerable<BrowseStatusModel> BrowseByStatus(int[] StatusSelections)
{
IQueryable<BrowseStatusModel> query = _db.VendorProfiles
.Include("VendorStatusHistory")
.Include("StatusCodes")
.Select(s => new BrowseStatusModel
{
ProfileID = s.ProfileID,
Name = s.Name,
CompanyName = s.CompanyName,
CompanyDBA = s.CompanyDBA,
DateCreated = s.DateCreated,
Status = s.VendorStatusHistories.OrderByDescending(o => o.DateCreated).FirstOrDefault().Id,
StatusDate = s.VendorStatusHistories.OrderByDescending(o => o.DateCreated).FirstOrDefault().DateCreated
})
.OrderBy(x => x.ProfileID);
foreach (int status in StatusSelections)
{
query = query.Where(x => x.Status == status);
}
return query;
}
The above foreach loop works but, unfortunately creates AND condition where ALL selections must be true instead of ANY. I figured I would have to use a where clause with the following in some way but have been unsuccessful at the correct syntax.
.AsQueryable().Any();
Use contains in the place of that foreach loop
query = query.Where(x => StatusSelections.Contains(x.Status))
Here is the original logic
(scrape_datas = ScrapeData.find(
:all, :conditions =>
"artist_status = 'NOT_FOUND'
AND blacklisted = 1
AND extracted = 0
and not EXISTS(
SELECT * FROM artist_name_suggestions where original = artist_name
)
I've been able to split up the first part better
scrape_datas = ScrapeData.where(
:artist_status => 'NOT_FOUND',
:blacklisted => 1,
:extracted => 0
)
Although having issues getting the "and not EXISTS" query into the mix
and not EXISTS(
SELECT * FROM artist_name_suggestions where original = artist_name
)
Thanks!
Firstly you can extract simple scopes:
scope :not_found, where(:artist_status => 'NOT_FOUND')
scope :blacklisted, where(:blacklisted => 1)
scope :extracted, where(:extracted => 0)
Then add a query method (assume artist_name is a column of scrape_datas):
def self.no_suggestions
scrape_datas = ScrapeData.arel_table
suggestions = ArtistNameSuggestion.arel_table
where(ArtistNameSuggestion.where(
suggestions[:original].eq(scrape_datas[:artist_name])
).exists.not)
end
Now you can do something like this:
ScrapeData.not_found.blacklisted.extracted.no_suggestions
I need to select count of row with a condition:
Query to collect the full count:
var searchs = searchQuery.SelectList
(list => list
.SelectGroup(order => order.Id).WithAlias(() => groupResult.GlobalId)
.SelectCount(() => _transaction.ReturnStatus).WithAlias(() => groupResult.DeclineCount)
)
I need count of transactions that equals 201. Something like this:
.SelectCount(() => _transaction.ReturnStatus == 201).WithAlias(() => groupResult.DeclineCount) //runtime error
Thanks in advance!
PS:
Original SQL Query:
SELECT TOP 100
globalOrd.ID AS GlobalId ,
SUM(CASE WHEN transact.returnStatus = 201 THEN 1
ELSE 0
END) AS DeclineCount
FROM Orders.Global globalOrd
INNER JOIN Orders.TransactionDetail transactDet ON globalOrd.ID = transactDet.DetailID
INNER JOIN Orders.[Transaction] transact ON transactDet.TransactionID = transact.ID
GROUP BY globalOrd.ID
If you don't need the total count in the same query you can simply add in the restriction before the SelectList:
var searchs = searchQuery.SelectList
(list => list
.Where(() => _transaction.ReturnStatus == 201)
.SelectGroup(order => order.Id).WithAlias(() => groupResult.GlobalId)
.SelectCount(() => _transaction.ReturnStatus).WithAlias(() => groupResult.DeclineCount)
)
If however, you want both the total and the restricted count, you would have to use a SqlProjection for the latter doing something like:
SUM(CASE {alias}.ReturnStatus WHEN 201 THEN 1 ELSE 0 END)
I need to translate this SQL statement to a Linq-Entity query...
SELECT name, count(name) FROM people
GROUP by name
Query syntax
var query = from p in context.People
group p by p.name into g
select new
{
name = g.Key,
count = g.Count()
};
Method syntax
var query = context.People
.GroupBy(p => p.name)
.Select(g => new { name = g.Key, count = g.Count() });
Edit: EF Core 2.1 finally supports GroupBy
But always look out in the console / log for messages. If you see a notification that your query could not be converted to SQL and will be evaluated locally then you may need to rewrite it.
Entity Framework 7 (now renamed to Entity Framework Core 1.0 / 2.0) does not yet support GroupBy() for translation to GROUP BY in generated SQL (even in the final 1.0 release it won't). Any grouping logic will run on the client side, which could cause a lot of data to be loaded.
Eventually code written like this will automagically start using GROUP BY, but for now you need to be very cautious if loading your whole un-grouped dataset into memory will cause performance issues.
For scenarios where this is a deal-breaker you will have to write the SQL by hand and execute it through EF.
If in doubt fire up Sql Profiler and see what is generated - which you should probably be doing anyway.
https://blogs.msdn.microsoft.com/dotnet/2016/05/16/announcing-entity-framework-core-rc2
A useful extension is to collect the results in a Dictionary for fast lookup (e.g. in a loop):
var resultDict = _dbContext.Projects
.Where(p => p.Status == ProjectStatus.Active)
.GroupBy(f => f.Country)
.Select(g => new { country = g.Key, count = g.Count() })
.ToDictionary(k => k.country, i => i.count);
Originally found here:
http://www.snippetsource.net/Snippet/140/groupby-and-count-with-ef-in-c
Here are simple examples of group-by in .NET Core 2.1:
var query = this.DbContext.Notifications
.Where(n => n.Sent == false)
.GroupBy(n => new { n.AppUserId })
.Select(g => new { AppUserId = g.Key, Count = g.Count() });
var query2 = from n in this.DbContext.Notifications
where n.Sent == false
group n by n.AppUserId into g
select new { id = g.Key, Count = g.Count()};
Both of these translate to:
SELECT [n].[AppUserId], COUNT(*) AS [Count]
FROM [Notifications] AS [n]
WHERE [n].[Sent] = 0
GROUP BY [n].[AppUserId]
with EF 6.2 it worked for me
var query = context.People
.GroupBy(p => new {p.name})
.Select(g => new { name = g.Key.name, count = g.Count() });