I want to fetch a records based on NOT IN clause with multiple properties but core data is returning empty result. Below is the predicate I am using
let predicate = NSPredicate(format: "NOT (id in %# && field2 in %# && field3 in %#)
I am not getting any errors so I assume syntax is right but core data returning empty result set.
try using NSCompoundPredicate notPredicateWithSubpredicate - https://developer.apple.com/reference/foundation/nscompoundpredicate/1409462-init
Related
I have the following query trying to get count of a query:
var testQuery = Db
.From<Blog>()
.LeftJoin<BlogToBlogCategory>()
.Where(x => x.IsDeleted == false)
.OrderBy(x => x.ConvertedPrice);
var testCount = Db.Scalar<int>(testQuery.Select<Blog>(x => Sql.CountDistinct(x.Id)));
var results = Db.LoadSelect(testQuery.SelectDistinct());
It gives error:
42803: column "blog.converted_price" must appear in the GROUP BY clause or be used in an aggregate function
Issue seems to be the orderby statement. If I remove it then the error goes away. Why does this stop count distinct working?
I am having to clear orderby on all queries I do like this. Is it supposed to work this way?
Also I just realised count is wrong. Results is 501 unique records and testCount is 538.
What am I doing wrong?
Whenever in doubt with what an OrmLite query is generating, you can use the BeforeExecFilter to inspect the DB command before its executed or to just output the query to the Console you can use:
OrmLiteUtils.PrintSql();
You shouldn't be using OrderBy with aggregate scalar functions like COUNT which is meaningless and will fail in your case because it needs to included the GROUP BY clause for joined table queries.
Your specifically querying for COUNT(DISTINCT Id) if you wanted the row count for the query you can instead use:
var testCount = Db.RowCount(testQuery);
If you wanted to use COUNT(*) instead, you can use:
var testCount = Db.Count(testQuery);
I'm getting the order by clause as a String from the application configuration.
Example
String orderByString = "NAME DESC, NUMBER ASC";
Now I want to use this order by in jOOQ query:
Result<KampagneRecord> records = repository.dsl()
.selectFrom(KAMPAGNE)
.orderBy(orderByString)
.fetch();
Unfortunately orderBy does not accept a String.
Is there a way to add the order by clause to the query?
You could use the fact that jOOQ does not validate your plain SQL templating, and just wrap your string in a DSL.field(String):
Result<KampagneRecord> records = repository.dsl()
.selectFrom(KAMPAGNE)
.orderBy(field(orderByString))
.fetch();
Of course, you will have to make sure that syntactical correctness is guaranteed, and SQL injection is prevented.
Some edge cases that rely on jOOQ being able to transform your SQL's ORDER BY clause might stop working, but in your simple query example, this would not apply.
An alternative solution, in very simple cases, is to preprocess your string. It seems as though this would work:
String orderByString = "NAME DESC, NUMBER ASC";
List<SortField<?>> list =
Stream.of(orderByString.split(","))
.map(String::trim)
.map(s -> s.split(" +"))
.map(s -> {
Field<?> field = field(s[0]);
return s.length == 1
? field.sortDefault()
: field.sort("DESC".equalsIgnoreCase(s[1])
? SortOrder.DESC
: SortOrder.ASC
);
})
.collect(Collectors.toList());
System.out.println(list);
This list can now be passed to the orderBy() clause.
I am using Entity Framework and Linq to SQL to select data from a database table. In my result object I am getting the tables being referenced by the selected table. Is there any way to restrict the referenced tables and get only the selected table. Below is my code.
var routeMaster = (from Ec_RouteMaster in travelServicesDBEntities.ExtraComfort_RouteMaster where (Ec_RouteMaster.Source == flights.OriginCode && Ec_RouteMaster.Destination == flights.DestinationCode && Ec_RouteMaster.AirCraftType == flights.AircraftType && Ec_RouteMaster.Switch == "1") select Ec_RouteMaster).FirstOrDefault();
I want data only from ExtraComfort_RouteMaster. But EF fetched data also from the tables referenced by the primary key of ExtraComfort_RouteMaster. How to do it?
Have a look at this and check the sections about lazy loading.
Setup:
I have a Core Data object A that has a to-many relation to B. Call the relation "items". So, a.items returns all B-s associated with A.
Now, I have a manually composed NSSet "itemSet" of B objects.
I want to do the following:
return all A objects whose "items" relation exactly matches itemSet
How do I construct a predicate for that? I’ve tried this:
NSPredicate *predicate = [NSPredicate predicateWithFormat:
#"(ALL items in %#)", itemSet];
But that just gives me Unsupported predicate (null).
This:
NSPredicate *predicate = [NSPredicate predicateWithFormat:
#"(items in %#)", itemSet];
tells me unimplemented SQL generation for predicate. Interesting, but not helpful.
So what’s the right way to filter the relation with a set?
The following predicate could work:
[NSPredicate predicateWithFormat:#"(items.#count == %d) AND (SUBQUERY(items, $x, $x IN %#).#count == %d)",
itemSet.count, itemSet, itemSet.count];
The predicate checks first that the number of items is equal to the size of the given itemSet, and then checks that the number of items which are member of itemSet is also equal to the size of itemSet. If both are true, then items must be equal to itemSet.
Have you tried:
NSPredicate *predicate = [NSPredicate predicateWithFormate:#"items == %#", itemSet];
Alternatively, pull out a subset with a simpler predicate and filter them outside of the fetch request. i.e.
Set a predicate for the number of items in the relationship to the be the same as the number of items in your comparison set.
Fetch the results
Filter these results to show only the ones where the sets contain the same items.
I've a problem with LINQ. Basically a third party database that I need to connect to is using the now depreciated text field (I can't change this) and I need to execute a distinct clause in my linq on results that contain this field.
I don't want to do a ToList() before executing the Distinct() as that will result in thousands of records coming back from the database that I don't require and will annoy the client as they get charged for bandwidth usage. I only need the first 15 distinct records.
Anyway query is below:
var query = (from s in db.tSearches
join sc in db.tSearchIndexes on s.GUID equals sc.CPSGUID
join a in db.tAttributes on sc.AttributeGUID equals a.GUID
where s.Notes != null && a.Attribute == "Featured"
select new FeaturedVacancy
{
Id = s.GUID,
DateOpened = s.DateOpened,
Notes = s.Notes
});
return query.Distinct().OrderByDescending(x => x.DateOpened);
I know I can do a subquery to do the same thing as above (tSearches contains unique records) but I'd rather a more straightfoward solution if available as I need to change a number of similar queries throughout the code to get this working.
No answers on how to do this so I went with my first suggestion and retrieved the unique records first from tSearch then constructed a subquery with the non unique records and filtered the search results by this subquery. Answer below:
var query = (from s in db.tSearches
where s.DateClosed == null && s.ConfidentialNotes != null
orderby s.DateOpened descending
select new FeaturedVacancy
{
Id = s.GUID,
Notes = s.ConfidentialNotes
});
/* Now filter by our 'Featured' attribute */
var subQuery = from sc in db.tSearchIndexes
join a in db.tAttributes on sc.AttributeGUID equals a.GUID
where a.Attribute == "Featured"
select sc.CPSGUID;
query = query.Where(x => subQuery.Contains(x.Id));
return query;