Need help with converting this sql query
SELECT c.studentId, c.Name
FROM Classes c
WHERE c.Class = 'Math'
AND c.Grade IN 'yoklama', '2')
AND c.studentId IN (
SELECT c2.studentId
FROM Classes c2
WHERE c2.Class = 'Eng'
AND c.Grade IN ('yoklama', '2'))
I was trying like this but these keeps giving error that I am doing this wrong
var reportDtos = context.Classes.Where(c => pt.Class == 'Math' && c.Grade.HasValue
&& c.Grade == '2' || c.Grade == 'yoklama' && c.studentId.Contains(context.ParticipTests
.Where(x => x.Class == 'Math' &&x.Grade.HasValue && x.Grade == '2' || x.Grade == 'yoklama')
.ToList()
.Select(x => ))
.Include("Area")
.Include("Questions")
.Include("Class.Test")
.ToList()
.Select(pt => new ReportDto
{
...
}
First off, strings must always be double quoted " and not single quoted ' like you have some.
If you write some code by splitting up the steps it makes it more understandable.
var validGrades = new List<string> { "Yoklama", "2" };
var studentsInEnglish = context.ParticipTests
.Where(x => x.Class.Equals("Eng") && validGrades.Contains(x.Grade))
.Select(x => x.studentId);
var studentsInMath = context.Classes
.Where(x => x.Class.Equals("Math") && validGrades.Contains(x.Grade) && studentsInEnglish.Contains(x.studentId))
.Select(x => (x.studentId, x.Name));
Now with this, (if you really still want to) you can write a single query by plugging in and replacing.
var reportDtos = context.ParticipTests
.Where(
x => x.Class.Equals("Math") &&
new List<string> { "Yoklama", "2" }.Contains(x.Grade) &&
context.Classes
.Where(
y => y.Class.Equals("Eng") &&
new List<string> { "Yoklama", "2" }.Contains(y.Grade))
.Select(y => y.studentId)
.Contains(x.studentId))
.Select(x => (x.studentId, x.Name))
.ToList();
...But I like the first way better.
Related
I have a following query
return _context.Table1
.Where(x => x.ContactId == contactKey.Id)
.Include(x => x.Table2)
.Include(x => x.Table3.Table4)
.Select(a =>
new MyReadModel
{
PriorityAssignment = true,
LastContactedDate = (a.Table3.Table4 != null && a.Table3.Table4.FirstOrDefault(h =>
h.Id == a.Table2.FkId
) != null ?
a.Table3.Table4.FirstOrDefault(h => && h.Id == a.Table2.FkId
).LastContactedDatetime : default
)
}
)
.ToListAsync();
What i wants is to simplify LastContactedDate assignment with in select. I think we can assign
a.Table3.Table4.FirstOrDefault(h =>
h.Id == a.Table2.FkId
)
to some variable but can't able to do it
can someone identify what is needed
With EF Core you don't have to check for null, LINQ Translator do not execute your code, but uses it for translation to the SQL. Also Includes is not needed if you do not retrieve whole objects.
return await _context.Table1
.Where(x => x.ContactId == contactKey.Id)
.Select(a => new MyReadModel
{
PriorityAssignment = true,
LastContactedDate = (DateTime?)a.Table3.Table4.Where(h => h.Id == a.Table2.FkId)
.OrderByDescending(h => LastContactedDatetime)
.Select(h => LastContactedDatetime)
.FirstOrDefault()
}).ToListAsync();
you can use it like this example
List<string> someList= new List<string>();
someList= someList.Select(x =>
{
var newVariable= "newVariable";
return newVariable;
}).ToList();
in your case
return _context.Table1
.Where(x => x.ContactId == contactKey.Id)
.Include(x => x.Table2)
.Include(x => x.Table3.Table4)
.Select(a => {
Table4 newVariable = null;
if(a.Table3.Table4 != null)
newVariable = a.Table3.Table4.FirstOrDefault(h => h.Id == a.Table2.FkId;
var result = new MyReadModel
{
PriorityAssignment = true,
LastContactedDate = (newVariable != null ? newVariable.LastContactedDatetime : default
)
};
}
) .ToListAsync();
I have a LINQ query which has three Where clauses. In each Where clause I am looking up the same set of items in order to compare values:
var items = _umbracoHelper.GetPage(ItemsPage.ModelTypeAlias).Children
.Where(x => level1Category == 0 || x
.GetPropertyValue<IEnumerable<IPublishedContent>>(UmbracoAlias.Item.Categories)
.Select(y => y.Id).Contains(level1Category))
.Where(x => !level2Categories.Any() || x
.GetPropertyValue<IEnumerable<IPublishedContent>>(UmbracoAlias.Item.Categories)
.Select(y => y.Id).Intersect(level2Categories.AsEnumerable()).Any())
.Where(x => !level3Categories.Any() || x
.GetPropertyValue<IEnumerable<IPublishedContent>>(UmbracoAlias.Item.Categories)
.Select(y => y.Id).Intersect(level3Categories.AsEnumerable()).Any());
Is there a way I can get the value of UmbracoAlias.Items.Categories once and store that value to be used in the other where clauses without causing the GetPropertyValue method to execute more than once?
You can pair up each item with category IDs, like this:
var items = _umbracoHelper.GetPage(ItemsPage.ModelTypeAlias).Children
.Select(c => new {
Child = c
, CategoryIds = c
.GetPropertyValue<IEnumerable<IPublishedContent>>(UmbracoAlias.Item.Categories)
.Select(y => y.Id)
.ToList()
})
.Where(x => level1Category == 0 || x.CategoryIds.Contains(level1Category))
.Where(x => !level2Categories.Any() || x.CategoryIds.Intersect(level2Categories.AsEnumerable()).Any())
.Where(x => !level3Categories.Any() || x.CategoryIds.Intersect(level3Categories.AsEnumerable()).Any())
.Select(x => x.Child);
This does the filtering on children paired up with their category IDs, and then keeps only the Child object in the final projection.
You could further simplify this by combining all three Where clauses:
var items = _umbracoHelper.GetPage(ItemsPage.ModelTypeAlias).Children
.Where(c => {
var categoryIds = c
.GetPropertyValue<IEnumerable<IPublishedContent>>(UmbracoAlias.Item.Categories)
.Select(y => y.Id)
.ToList();
if (level1Category != 0 && !categoryIds.Contains(level1Category)) {
return false;
}
if (level2Categories.Any() && !categoryIds.Intersect(level2Categories.AsEnumerable()).Any()) {
return false;
}
if (level3Categories.Any() && !categoryIds.Intersect(level3Categories.AsEnumerable()).Any()) {
return false;
}
return true;
});
I've written this code which works:
var uniqueCustomerIdList = services
.GroupBy(x => x.CustomerId)
.Select(cl => new Customer
{
CustomerId = cl.First().CustomerId,
CustomerName = cl.First().CompanyName,
PdfServices = services.Where(x => x.CustomerId == cl.First().CustomerId).ToList(),
PdfServiceLines = services.Where(x => x.CustomerId == cl.First().CustomerId).ToList()
.GroupBy(l => l.ServiceDescription)
.Select(cy => new PdfServiceLine
{
ServiceName = cy.First().ServiceDescription,
Quantity = cy.Count(),
UnitPrice = cy.First().PlanCharge,
ServiceCharges = services.Where(x => x.CustomerId == cl.First().CustomerId && x.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.TotalBill),
UsageCharges = usage.Where(x => x.CustomerId == cl.First().CustomerId && x.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.Charge),
Total = cy.Sum(c => c.PlanCharge),
}).ToList(),
PdfUsages = usage.Where(x => x.CustomerId == cl.First().CustomerId).ToList()
})
.ToList();
I wanted to know if it's possible to reference values from the outer Select statement in the inner statement? As it looks rather clunky at the moment.
For instance in the outer Customer select I use PdfServices - can I use that in the inner select where I have ServiceCharges?
ServiceCharges = PdfServices.Where(s => s.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.TotalBill)
instead of
ServiceCharges = services.Where(x => x.CustomerId == cl.First().CustomerId && x.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.TotalBill),
Thanks,
Lee.
The results that you want to re-use are members of an anonymous object, not variables. As such, you cannot expect them to be available, like a variable would be, to the inner lambda. If you re-wrote your statement, you could store them in intermediate variables:
var uniqueCustomerIdList = services
.GroupBy(x => x.CustomerId)
.Select(cl =>
{
var pdfServices = services.Where(x => x.CustomerId == cl.First().CustomerId).ToList();
return new Customer
{
CustomerId = cl.First().CustomerId,
CustomerName = cl.First().CompanyName,
PdfServices = pdfServices,
PdfServiceLines = pdfServices
.GroupBy(l => l.ServiceDescription)
.Select(cy => new PdfServiceLine
{
ServiceName = cy.First().ServiceDescription,
Quantity = cy.Count(),
UnitPrice = cy.First().PlanCharge,
ServiceCharges = services.Where(x => x.CustomerId == cl.First().CustomerId && x.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.TotalBill),
UsageCharges = usage.Where(x => x.CustomerId == cl.First().CustomerId && x.ServiceDescription == cy.First().ServiceDescription).Sum(y => y.Charge),
Total = cy.Sum(c => c.PlanCharge),
}).ToList(),
PdfUsages = usage.Where(x => x.CustomerId == cl.First().CustomerId).ToList()
};
})
.ToList();
Note that the lamda body now uses curly braces and a return statement. This is not convertible to an expression tree, and some ORM frameworks, like Entity Framework, will not be able to translate the lamda into SQL.
I've currently got a working multi level predicate shown below...
var predicate = PredicateBuilder.New<Patient>();
foreach (var code in codeArray) // ect..["AB12", "W231", "Q213"]
{
string localCode = code;
predicate.Or(p => p.Requests.Any(
u => u.Records.Any(
t => t.OutgoingRecords.Any(
s => s.Code == localCode)
)
)
);
}
res = query.AsExpandable().Where(predicate);
// Query is built up from an outside source and is eventually turned into a list via .ToListAsync()
Which is fine except as far as I'm aware it is producing a query in the form of...
query = p => p.PatientEpisodes.Any(u => u.EpisodeGroupings.Any(t => t.EpisodeDiagnoses.Any(s => s.Code == 'AB12'))) ||
p.PatientEpisodes.Any(u => u.EpisodeGroupings.Any(t => t.EpisodeDiagnoses.Any(s => s.Code == 'W231'))) ||
p.PatientEpisodes.Any(u => u.EpisodeGroupings.Any(t => t.EpisodeDiagnoses.Any(s => s.Code == 'Q213')))
Which is just overkill (and somewhat wrong) when all I really should be producing is...
query = p => p.PatientEpisodes.Any(u => u.EpisodeGroupings.Any(t => t.EpisodeDiagnoses.Any(s => s.Code == 'AB12' || s.Code == 'W312' || s.Code == 'Q213')))
Is there a way to insert the predicate at a sub level of a query such as below? My current attempts to do so have failed so far.
var predicate = PredicateBuilder.New<RecordCode>();
foreach (var code in codeArray)
{
string localCode = code;
predicate.Or(p => p.Code == localCode);
}
query = query.AsExpandable().Where(
s => s.Requests.Any(
c => c.Records.Any(
d => d.OutgoingRecords.Any(predicate))));
Many thanks in advance.
In Linqpad, i can see the correct list. But in code, after putting in the list collection, order by doesn't work for BeginDate. If i use BeginDate with Max, it works. I don't understand where i am wrong?
var templist = contentRepository
.Get(q => (q.Status == (int)StatusEnum.Active) &&
(q.CategoryId == category.GetHashCode() || q.Category.ParentId == category.GetHashCode())
&& q.MinorVersion == 0
&& q.MajorVersion > 0)
.GroupBy(q => q.VersionId)
.OrderByDescending(q => q.Key)
.Select(q => new
{
VersionId = q.Key,
Id = q.Max(x => x.Id),
MajorVersion = q.Max(x => x.MajorVersion),
UpdatedAt = q.Max(x => x.UpdatedAt),
//BeginDate = q.Max(x=>x.BeginDate),
BeginDate = (q.OrderByDescending(x => x.Id).Take(1).Select(x=>x.BeginDate)).First(),
Title = (q.OrderByDescending(x => x.Id).Take(1).Select(x => x.Title)).First(),
ShowOnHomePage = (q.OrderByDescending(x => x.Id).Take(1).Select(x=>x.ShowOnHomePage)).First()
})
.OrderByDescending(x => x.BeginDate)
.Take(maxItemCount)
.ToList();
List<ContentEntity> contents = new List<ContentEntity>();
templist.ForEach(q => contents.Add(
contentRepository
.Get(x => x.VersionId == q.VersionId && x.MajorVersion == q.MajorVersion && x.MinorVersion == 0)
.FirstOrDefault()
));
return contents.Where(q => q.ShowOnHomePage == true)
.OrderByDescending(q => q.MajorVersion)
.OrderByDescending(q => q.BeginDate)
.Take(maxItemCount)
.ToList();
You are ordering by Id, not by BeginDate. Equivalent code for
q.Max(x => x.BeginDate)
Will be
q.OrderByDescending(x => x.BeginDate).Take(1).Select(x => x.BeginDate).First()
Or simplified
q.OrderByDescending(x => x.BeginDate).First().BeginDate