In the table ReservationWorkerPeriods there are records of all workers that are planned to work on a given period on any possible machine.
The additional table WorkerOnMachineOnConstructionSite contains columns workerId, MachineId and ConstructionSiteId.
From the table ReservationWorkerPeriods I would like to retrieve just workers who work on selected machine.
In order to retrieve just relevant records from WorkerOnMachineOnConstructionSite table I have written the following code:
var relevantWorkerOnMachineOnConstructionSite = (from cswm in currentConstructionSiteSchedule.ContrustionSiteWorkerOnMachine
where cswm.MachineId == machineId
select cswm).ToList();
workerOnMachineOnConstructionSite = relevantWorkerOnMachineOnConstructionSite as List<ContrustionSiteWorkerOnMachine>;
These records are also used in the application so I don't want to bypass the above code even if is possible to directly retrieve just workerPeriods for workers who work on selected machine. Anyway I haven't figured out how it is possible to retrieve the relevant workerPeriods once we know which userIDs are relevant.
I have tried the following code:
var userIDs = from w in workerOnMachineOnConstructionSite select new {w.WorkerId};
List<ReservationWorkerPeriods> workerPeriods = currentConstructionSiteSchedule.ReservationWorkerPeriods.ToList();
allocatedWorkers = workerPeriods.Where(wp => userIDs.Contains(wp.WorkerId));
but it seems to be incorrect and don't know how to fix it. Does anyone know what is the problem and how it is possible to retrieve just records which contain userIDs from the list?
Currently, you are constructing an anonymous object on the fly, with one property. You'll want to grab the id directly with (note the missing curly braces):
var userIDs = from w in workerOnMachineOnConstructionSite select w.WorkerId;
Also, in such cases, don't call ToList on it - the variable userIDs just contains the query, not the result. If you use that variable in a further query, the provider can translate it to a single sql query.
Related
For table cmdb_rel_ci, I want to retrieve unique parent.sys_class_name with count for "type=In Rack::Rack contains". I am doing practice in out of the box instance.
At table level URL is as below:
URL
I want to retrieve result from above URL with my below script.
var count = new GlideAggregate('cmdb_rel_ci');
count.addQuery('type','e76b8c7b0a0a0aa70082c9f7c2f9dc64');// sys_id of type In Rack::Rack contains e76b8c7b0a0a0aa70082c9f7c2f9dc64
count.addAggregate('COUNT', 'parent.sys_class_name');
count.query();
while(count.next()){
var parentClassName = count.parent.sys_class_name.toString();
var parentClassNameCount = count.getAggregate('COUNT','parent.sys_class_name');
gs.log(parentClassName + " : " + parentClassNameCount );
}
The issue is I am getting parentClassName empty.
Try this instead:
var parentClassName = count.getValue("parent.sys_class_name")
Since it's a GlideAggregate query (instead of GlideRecord), the query being issued isn't returning all of the fields on the target table. With GlideRecord, dot-walking through a reference field (e.g. parent.sys_class_name) automatically resolves that referenced record to provide access to its field values. This is made possible by the fact that the driving/original query brought back the value of the parent field. This is not happening with GlideAggregate. The query in this case basically looks like:
SELECT cmdb1.`sys_class_name` AS `parent_sys_class_name`, count(*)
FROM (cmdb_rel_ci cmdb_rel_ci0 LEFT JOIN cmdb cmdb1 ON cmdb_rel_ci0.`parent` = cmdb1.`sys_id` )
WHERE cmdb_rel_ci0.`type` = 'e76b8c7b0a0a0aa70082c9f7c2f9dc64'
GROUP BY cmdb1.`sys_class_name`
ORDER BY cmdb1.`sys_class_name`
So, you actually have access specifically to that dot-walked sys_class_name that's being grouped, but not through the dot-walk. The call to getValue("parent.sys_class_name") is expectedly resolved to the returned column aliased as parent_sys_class_name.
That being said, what you're doing probably should also work, based on user expectations, so you've not done anything incorrect here.
I have Documents table and Signs table. Document record can be related with many records in Signs table.
Now, I want to get all records of Documents table when document ID appears in Signs table.
Here I get all documents:
var documents = (from c in context.documents select c);
Here I get all my signs and save into List:
var myDocuments = (from s in context.signs where s.UserId== id select s.ID).ToList();
This list contains collection on document ID.
And here, I'm trying to get all documents that exists in myDocuments list:
documents.Where(item => myDocuments.Contains(item.ID));
But, when I do .ToList() allways return all records (in database only exists one compatible record)
What is wrong in LinQ statement?
The problem is that this statement doesn't modify the contents of documents, it merely returns the results (which you're not doing anything with):
documents.Where(item => myDocuments.Contains(item.ID));
documents is still the full list.
Change this line to something like:
var matchingIDDocs = documents.Where(item => myDocuments.Contains(item.ID));
And then use matchingIDDocs in place of "documents" later in your code.
I need to write a query in such way that the array(collection) is contain only sub query objects.
Suppose we have the two tables as follows:
TableA:
objectId, name
TableB:
objectId, names[array of name: parse pointer collection]
Here is my code which I tried:
// sub query
var subQuery = new Parse.Query('TableA');
subQuery.doesNotExist('name');
// main query
var query = new Parse.Query('TableB');
query.exists("names");
//query.containsAll("names", subQuery); // this means names should contain all subQuery, so this is not use full for me.
query.matchesQuery("names", subQuery);
This code is running fine, but this is not working as I want and also not showing the any error.
It seems that you don't need a subquery per se, but rather to first query your list of names, and then use that in your main query. What you seem to be looking for is: containedIn( key, values ) , as in:
query.containedIn("name", namesFromFirstQuery)
db.AdDetails.Where( u => u.OwnerGUID == CurrentUserProviderKey)
I have an adDetails table that has an OwnerGUID field.
I want to pull out only ad details that belong to the currenly logged in user.
My query does not show any where clauses in the SQL when I look at it in the debugger.
Can someone help me figure out what is wrong with my statement and if all rows in the table will be brought back then all 10K records put though a where on the webserver?
I am really new to this.
Using the Where extension method will filter down the results.
Queries in Entity Framweork are not executed until you iterate over them. If you do:
var query = db.Where(u => u.OwnerGUID == key);
This does not execute the query. When you do the following:
var list = list.ToList();
OR
foreach( var item in query) { ... }
That is when the query will be executed in SQL. The results should be filtered with your WHERE clause at this point.
Is this linq query efficient?
var qry = ((from member in this.ObjectContext.TreeMembers.Where(m => m.UserId == userId && m.Birthdate == null)
select member.TreeMemberId).Except(from item in this.ObjectContext.FamilyEvents select item.TreeMemberId));
var mainQry = from mainMember in this.ObjectContext.TreeMembers
where qry.Contains(mainMember.TreeMemberId)
select mainMember;
Will this be translated into multiple sql calls or just one? Can it be optimised? Basically I have 2 tables, I want to select those records from table1 where datetime is null and that record should not exist in table2.
The easiest way to find out if the query will make multiple calls is to set the .Log property of the data context. I typically set it to write to a DebugOutputWriter. A good example for this kind of class can be found here.
For a general way of thinking about it however, if you use a property of your class that does not directly map to a database field in a where clause or a join clause, it will typically make multiple calls. From what you have provided, it looks like this is not the case for your scenario, but I can't absolutely certain and suggest using the method listed above.