I have a query in linq that fetch students assessments data something like
new {x.StudentId, x.StudentAssessmentId, x.AssessmentName, x.SubmittedDate}
then I perform some operations on this list to get only last added student assessment per student, I get last studentassessment by finding the max id of studentassessment,
so I finally get last studentassessments data of all the students.
Is there a way to do this directly in the initial list?
I thought about the way to group the results by student Id and select max of studentassessmentid, like
group x.StudentAssessmentId by x.StudentId
select new {x.Key, x.Max()}
in this way I will get student with there last studentassessmentid which is what I want but this will only give me studentassessment ids while I want other data also like AssessmentName, SubmittedDate etc.
Try something like this:
group x.StudentAssessmentId
by new {
x.StudentId,
x.AssessmentName,
x.SubmittedDate }
into g
select new
{
g.Key.StudentId,
g.Key.AssessmentName,
g.Key.SubmittedDate,
g.Max(),
}
Related
I am trying to get a list from the database containing two or more lists inside that list.(using .net core, entity framework).Assume I have two table call header and details table.
Header Table
Detail Table
And I want the result like this:
{
"data":[
{
"Country":"Singapore",
"Hospital_List":[
{
"Hospital_Name":"SG Host A"
},
{
"Hospital_Name":"SG Host A"
}
]
},
{
}
]
}
I only know two ways to get the result like this,First Way, select Country list data with blank Hospital list as List,then for loop that list to select related Hospital list from db again.
And Second Way,select Country list data with blank Hospital list as IQueryable List,and then select related Hospital list via jointing with Hospital Table.So my question is
Which way should i used to get higher performance? And Is any other way?
Please remember there has a lot of field and data in my real table.
For loop give give you the lowest perfomance, because you will create SQL query for each iteration. Instead of this, try following solution:
from hospital in hospitals
group hospital by hospital.CID into gh
join country in countries
on gh.FirstOrDefault().CID equals country.CID
select new
{
Country = country.Country,
Hospital_List = from h in gh select h
}
EDITED:
And if your model created right you can use this code:
from hospital in hospitals
join country in countries
on hospital.Country equals country
group hospital by hospital.CID into gh
select new
{
Country = from h in gh select h.Country.Country,
Hospital_List = from h in gh select h
}
I have a Laravel 4.2 project where I get data from a SQL DB and I can display onto the page. I can select the single record just fine, but I want to also show the records around the one selected.
For example, I want to show the 5 records above and below the one selected. Im not sure how to do this in Laravel.
$gradschoolrange = MOGRadschool::where('Title', '=', $gradschool)->get();
In the above example $gradschool might be "Test College", it will return that with a value, but I want to show all the other related records around it with those values too. The results should look something like this:
ABC College
Another College
Blah College
Go To College
Test College
Yet Another College
Yo Yo College
College College
Something College
Eating College
As there's no ordering specified in your initial query, I'm assuming you want 5 next/previous records according to primary key (id? - if not, you would obviously need to change that) in the table?
Given that IDs may not be numerically sequential, we can't simply assume that the previous 5 rows will be the ID of the row with title = $gradschool minus 5, so wondered if this might work:
$initial = MOGRadschool::where('Title', $gradschool)->first(); // get the initial row with the title of $gradschool
$result = MOGRadschool::where('id', '<', $initial->id)->take(5)->orderBy('id', 'DESC') // new query getting the previous 5 rows, by ID
->union(MOGRadschool::where('id', '>', $initial->id)->take(5)) // union a second query getting the next 5 rows by ID
->get() // get the result as a collection
->add($initial) // add the initial row to the collection
->sort(); // sort the collection (by id) so that the initial row is in the middle
So the output is a collection containing the initial row in the middle, with up to 5 records either side. You also have the initial row to highlight the output, if you need that.
If you want it based on the IDs, which is what I understand from your issue, something like this should work:
$selectedGradSchool = MOGRadschool::where('Title', '=', $gradschool)->get()->first();
$aboveSelected = MOGRadschool::where('id', '<=', $selectedGradSchool->id)
->orderBy('id', 'desc')
->take('5')
->get();
$belowSelected = MOGRadschool::where('id', '>' $selectedgradSchool->id)
->take('5')
->get();
//Concatenate both results
$schoolRange = $aboveSelected->concat($belowSelected);
Now the collection should look similar to your desired result.
I hope one can help me, I am new in linq,
I have 2 tables name tblcart and tblorderdetail:
I just show some fields in these two tables to show whats my problem:
tblCart:
ID,
CartID,
Barcode,
and tblOrderDetail:
ID,
CartID,
IsCompleted
Barcode
when someone save an order, before he confirms his request,one row temporarily enter into the tblCart,
then if he or she confirms his request another row will be inserted into the tblOrderDetail ,
Now I wanna not to show the rows that is inserted into tblOrderDetailed(showing just temporarily rows which there is in tblCart),
In another words, if there is rows in tblCart with cartID=1 and at the same time there is the same row with CartID= 1 in tblOrderDetail, then I dont want that Row.
All in all, Just the rows that there isnt in tblOrderDetail, and the field to realize this is CartID,
I should mention that I make Iscompleted=true, and with that either we can exclude the rows we do not want,
I did this:
var cartItems = context.tblCarts
.Join(context.tblSiteOrderDetails,
w => w.CartID,
orderDetail => orderDetail.cartID,
(w,orderDetail) => new{w,orderDetail})
.Where(a=>a.orderDetail.cartID !=a.w.CartID)
.ToList()
however it doesn't work.
one example:
tblCart:
ID=1
CartID=1213
Barcode=4567
ID=2
CartID=1214
Barcode=4567
ID=3
CartID=1215
Barcode=6576
tblOrderDetail:
ID=2
CartID=1213
Barcode=4567
IsCompleted=true
with these data it should just show the last two Row in tblCart, I mean
ID=2
CartID=1214
Barcode=4567
ID=3
CartID=1215
Barcode=6576
This sounds like a case for WHERE NOT EXISTS in sql.
roughly translated this should be something like this in LINQ:
var cartItems = context.tblCarts.Where(crt => !context.tblSiteOrderDetails.Any(od => od.CartID == crt.cartID));
If you have a navigation property on cart to reference details (I'll assume it's called Details), then:
var results=context.tblCarts.Where(c=>!c.Details.Any(d=>d.IsCompleted));
In Excel I could, if I was in a table called 'Sales' that had four columns
Sales
Month, CustomerId, ProductId, TotalQuantity
Jan,1, CAR,
Feb,1, CAR,
I could add a formula:
=SUMIFS(Sales[Quantity],Sales[CustomerId],[#[CustomerId]])
That would go to the Sales table and sum the CustomerID column filtered by the CustomerID of the current row where the formula has been entered.
I am attempted to replicate this in a PowerBI Calculated Row but I can't get the # working for a row reference. It comes across like
TotalQuantity = CALCULATE(SUM(Sales[Quantity]),Sales[CustomerId] = Sales[CustomerId]))
Any idea how to get the equivalent # working?
I think the key function you are missing is EARLIER. That is not surprising because it has a misleading name - it really means "Current Row". You also need a FILTER function in the Filter parameter of CALCULATE, to reset the filter context to the entire table.
So your New Column function might look like this:
TotalQuantity = CALCULATE(SUM(Sales[Quantity]), FILTER(Sales, Sales[CustomerId] = EARLIER (Sales[CustomerId])))
Here's a neat example, from the most accessible source site for DAX formulas:
http://www.powerpivotpro.com/2013/07/writing-a-subtotal-calc-column-aka-the-simplest-use-of-the-earlier-function/
And FWIW here is the official doco on EARLIER:
https://msdn.microsoft.com/en-us/library/ee634551.aspx
I have the following SOQL query to display List of ABCs in my Page block table.
Public List<ABC__c> getABC(){
List<ABC__c> ListABC = [Select WB1__c, WB2__c, WB3__c, Number, tentative__c, Actual__c, PrepTime__c, Forecast__c from ABC__c ORDER BY WB3__c];
return ListABC;
}
As you can see in the above image, WB3 has number of records for A, B and C. But I want to display only 1 record for each WB3 group based on Actual__c. Only latest Actual__c must be displayed for each WB3 Group.
i.e., Ideally I want to display only 3 rows(one each for A,B,C) in this example.
For this, I have used GROUPBY and displayed the result using AggregateResults. Here is the result.
I got the Latest Actual Date for each WB3 as shown above. But the Tentative date is not corresponding to it. The Tentative Date is also the MAX in the list.
Here is the code I used
public List<SiteMonitoringOverview> getSPM(){
AggregateResult[] AgR = [Select WB_3__c, MAX(Tentaive_Date__c) dtTentativeDate , MAX(Actual_Date__c) LatestCDate FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
if(AgR.size()>0){
for(AggregateResult SalesList : AgR){
CustSumList.add(new SiteMonitoringOverview(String.ValueOf(SalesList.get('WB_3__c')), String.valueOf(SalesList.get('dtTentativeDate')), String.valueOF(SalesList.get('LatestCDate')) ));
}
}
return CustSumList;
}
I am forced to use MAX() for tentative date. I want the corresponding Tentative date of the MAX Actual Date. Not the Max Tentative Date.
For group A, the Tentative Date of Max Actual Date is 12/09/2012. But it is displaying the MAX tentative date: 27/02/2013. It should display 12/09/2012. This is because I am using MAX(Tentative_Date__c) in my code. Every column in the SOQL query must be either GROUPED or AGGREGATED. That's weird.
How do I get the required 3 rows in this example?
Any suggestions? Any different approach (looping within in groups)? how?
Just ran into this issue myself. The solution I came up with only works if you want the oldest or newest record from each grouping. Unfortunately it probably won't work in your case. I'll still leave this here incase it does happen to help someone searching for a solution to this issue.
AggregateResult[] groupedResults = [Select Max(Id), WBS_3__c FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
Calling MAX or MIN on the Id will let you get 1 record per group condition. You can then query other information. I my case I just need 1 record from each group and didn't really care which one it was.