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  • How is this Nested Set SQL query converted into a LINQ query?

    - by Chad
    Querying a Nested Set Model table, here's the SQL... how can this be written in LINQ? SELECT parent.name FROM nested_category AS node, nested_category AS parent WHERE node.lft BETWEEN parent.lft AND parent.rgt AND node.name = 'FLASH' ORDER BY parent.lft; particularly, the FROM part... never tried to do anything like that in LINQ.

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  • Filter to values in collection in one query

    - by dotnetdev
    Hi, I have the following LINQ query: List<string> Types = (List<string>) Directory.GetFiles(@"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727") Where(x => System.IO.Path.GetFileNameWithoutExtension(x).Contains("Microsoft")) .ToList<string>(); How could I modify this so it can only get the values stored in a collection, without writing another LINQ query (which I assume will impact performance?)? Thanks

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  • Request all titles by actor using LINQ to Netflix OData

    - by Mark Heath
    I'm experimenting with LINQPad to use LINQ to query the Netflix OData. I'm trying to search for all films with a particular actor in. For example: from t in Titles from p in t.Cast where p.Name == "Morgan Freeman" select t.Name this results in: NotSupportedException: Can only project the last entity type in the query being translated I also tried: from p in People from t in p.TitlesActedIn where p.Name == "Morgan Freeman" select t.Name which results in the following error: NotSupportedException: The method 'Select' is not supported I've tried a few other approaches, such as using Id's in the where clause, and selecting different things, but have got nowhere.

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  • Cross-table linq query with EF4/POCO

    - by Basiclife
    Hi All, I'm new to EF(any version) and POCO. I'm trying to use POCO entities with a generic repository in a "code-first" mode(?) I've got some POCO Entities (no proxies, no lazy loading, nothing). I have a repository(of T as Entity) which provides me with basic get/getsingle/getfirst functionality which takes a lambda as a parameter (specifically a System.Func(Of T, Boolean)) Now as I'm returning the simplest possible POCO object, none of the relationship parameters work once they've been retrieved from the database (as I would expect). However, I had assumed (wrongly) that my lambda query passed to the repository would be able to use the links between entities as it would be executed against the DB before the simple POCO entities are generated. The flow is: GUI calls: Public Function GetAllTypesForCategory(ByVal CategoryID As Guid) As IEnumerable(Of ItemType) Return ItemTypeRepository.Get(Function(x) x.Category.ID = CategoryID) End Function Get is defined in Repository(of T as Entity): Public Function [Get](ByVal Query As System.Func(Of T, Boolean)) As IEnumerable(Of T) Implements Interfaces.IRepository(Of T).Get Return ObjectSet.Where(Query).ToList() End Function The code doesn't error when this method is called but does when I try to use the result set. (This seems to be a lazy loading behaviour so I tried adding the .ToList() to force eager loading - no difference) I'm using unity/IOC to wire it all up but I believe that's irrelevant to the issue I'm having NB: Relationships between entities are being configured properly and if I turn on proxies/lazy loading/etc... this all just works. I'm intentionally leaving all that turned off as some calls to the BL will be from a website but some will be via WCF - So I want the simplest possible objects. Also, I don't want a change in an object passed to the UI to be committed to the DB if another BL method calls Commit() Can someone please either point out how to make this work or explain why it's not possible? All I want to do is make sure the lambda I pass in is performed against the DB before the results are returned Many thanks. In case it matters, the container is being populated with everything as shown below: Container.AddNewExtension(Of EFRepositoryExtension)() Container.Configure(Of IEFRepositoryExtension)(). WithConnection(ConnectionString). WithContextLifetime(New HttpContextLifetimeManager(Of IObjectContext)()). ConfigureEntity(New CategoryConfig(), "Categories"). ConfigureEntity(New ItemConfig()). ... )

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  • mysql query to dynamically convert row data to columns

    - by Anirudh Goel
    I am working on a pivot table query. The schema is as follows Sno, Name, District The same name may appear in many districts eg take the sample data for example 1 Mike CA 2 Mike CA 3 Proctor JB 4 Luke MN 5 Luke MN 6 Mike CA 7 Mike LP 8 Proctor MN 9 Proctor JB 10 Proctor MN 11 Luke MN As you see i have a set of 4 distinct districts (CA, JB, MN, LP). Now i wanted to get the pivot table generated for it by mapping the name against districts Name CA JB MN LP Mike 3 0 0 1 Proctor 0 2 2 0 Luke 0 0 3 0 i wrote the following query for this select name,sum(if(District="CA",1,0)) as "CA",sum(if(District="JB",1,0)) as "JB",sum(if(District="MN",1,0)) as "MN",sum(if(District="LP",1,0)) as "LP" from district_details group by name However there is a possibility that the districts may increase, in that case i will have to manually edit the query again and add the new district to it. I want to know if there is a query which can dynamically take the names of distinct districts and run the above query. I know i can do it with a procedure and generating the script on the fly, is there any other method too? I ask so because the output of the query "select distinct(districts) from district_details" will return me a single column having district name on each row, which i will like to be transposed to the column.

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  • SQL's Rownumber with Linq-to-entities

    - by mariki
    I am converting my project to use EF and also want to covert stored procedures into Linq-to-entities queries. This my SQL query (simple version) that I have trouble to convert: SELECT CategoryID, Title as CategoryTitle,Description, LastProductTitle,LastProductAddedDate FROM ( SELECT C.CategoryID, C.Title,C.Description, C.Section, P.Title as LastProductTitle, P.AddedDate as LastProductAddedDate, ROW_NUMBER() OVER (PARTITION BY P.CategoryID ORDER BY P.AddedDate DESC) AS Num FROM Categories C LEFT JOIN Products P ON P.CategoryID = C.CategoryID ) OuterSelect WHERE OuterSelect.Num = 1 In words: I want to return all Categories (from Categories table) and title and date of addition of the product (from Products table) that was added last to this category. How can I achieve this using Entity frame work query? In most efficient way.

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  • Linq-to-SQL statement issue

    - by Anicho
    I am basically looking to bind a search query to a gridview which is nice, but this must be done by a users input query (sort of like a search function). I can get single values and rows returned, but how would I get it to search all columns in my database for the inputted values and return it? My code so far is: Void SearchFunction() { TiamoDataContext context = new TiamoDataContext(); var search = from p in context.UserProfiles where = p.DanceType == UserSearchString select p; UserSearchGrid.DataSource = search; UserSearchGrid.DataBind(); } I tried p.equals but am pretty sure thats not the way to go about it.

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  • Linq query with aggregate function OrderBy

    - by Billy Logan
    Hello everyone, I have the following LinqToEntities query, but am unsure of where or how to add the orderby clause: var results = from d in db.TBLDESIGNER join s in db.TBLDESIGN on d.ID equals s.TBLDESIGNER.ID where s.COMPLETED && d.ACTIVE let value = new { s, d} let key = new { d.ID, d.FIRST_NAME, d.LAST_NAME } group value by key into g orderby g.Key.FIRST_NAME ascending, g.Key.LAST_NAME ascending select new { ID = g.Key.ID, FirstName = g.Key.FIRST_NAME, LastName = g.Key.LAST_NAME, Count = g.Count() }; This should be sorted by First_Name ascending and then Last_Name ascending. I have tried adding ordering but It has had no effect on the result set. Could someone please provide an example of where the orderby would go assuming the query above. Thanks, Billy

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  • XmlDocument from LINQ to XML query

    - by Ben
    I am loading an XML document into an XDocument object, doing a query and then returning the data through a web service as an XmlDocument object. The code below works fine, but it just seems a bit smelly. Is there a cleaner way to take the results of the query and convert back to an XDocument or XmlDocument? XDocument xd = XDocument.Load(Server.MapPath(accountsXml)); var accounts = from x in xd.Descendants("AccountsData") where userAccounts.Contains(x.Element("ACCOUNT_REFERENCE").Value) select x; XDocument xd2 = new XDocument( new XDeclaration("1.0", "UTF-8", "yes"), new XElement("Accounts") ); foreach (var account in accounts) xd2.Element("Accounts").Add(account); return xd2.ToXmlDocument();

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  • Several Small, Specific, MySQL Query Cache Questions

    - by Robbie
    I've look all over the web and in the questions asked here about MySQL caching and most of them seem very non-specific about a couple of questions that I have about performance and MySQL query caching. Specifically I want answers to these questions, assume for all questions that I have the query cache enabled and it is of type 2, or "DEMAND": Is the query cache per table, per database, or per server? Meaning if I have the cache size set to X and have T tables and D databases will I be caching TX, DX, or X amount of data? If I have table T1 which I regularly use the SQL_CACHE hint on for SELECT queries and table T2 which I never do, when I query T2 with a SELECT query will it check through the cache first before performing the query? *Note: I don't want to use the SQL_NO_CACHE for all T2 queries.* Assume the same situation as in question 2. If I alter (INSERT, DELETE) table T2 will any processing be done on the cache? For answers to 2 and 3, is this processing time negligible if T2 is constantly being altered and is the target of a majority of my SELECT queries?

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  • Problem with Linq query and date format

    - by Alan T
    Hi All I have a C# console application written using Visual Studio 2008. My system culture is en-GB. I have a Linq query that looks like this: var myDate = "19-May-2010"; var cus = from x in _dataContext.testTable where x.CreateDate == Convert.ToDateTime(myDate) select x; The resulting SQL query generates and error because it returns the dates as "19/05/2010" which it interprets as an incorrect date. For some reason even though my system culture is set to en-GB it looks like it's trying to intrepret it as a en-US date. Any ideas how I get around this? Thanks. Alan T

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  • ADO.NET Entity Model and LINQ

    - by Richard
    Hi all I'm using an ADO.NET Entity Model which I'm trying to query using LINQ. The problem I'm having is that I can't specify the where clause as I'd like. For instance, consider the following query: AccountsDM db = new AccountsDM(ConfigurationManager.ConnectionStrings["PrimaryEF"].ConnectionString); var accounts = from a in db.Accounts select a; foreach (var account in accounts) { foreach (var ident in account.Identifiers) { if (ident.Identifier == identifier) { // ident.Identifier is what I'd like to be filtering in the WHERE clause below } } } Ideally, I'd like that to become: var accounts = from a in db.Accounts where a.Identifiers.Identifier == identifier select a; I'm guessing I've probably not set up my Entity Model correctly in VS2010. Any advice you can offer would be gratefully received. Thanks, Richard.

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  • Is linq more efficient than it appears on the surface?

    - by Justin984
    If I write something like this: var things = mythings .Where(x => x.IsSomeValue) .Where(y => y.IsSomeOtherValue) Is this the same as: var results1 = new List<Thing>(); foreach(var t in mythings) if(t.IsSomeValue) results1.Add(t); var results2 = new List<Thing>(); foreach(var t in results1) if(t.IsSomeOtherValue) results2.Add(t); Or is there some magic under the covers that works more like this: var results = new List<Thing>(); foreach(var t in mythings) if(t.IsSomeValue && t.IsSomeOtherValue) results.Add(t); Or is it something completely different altogether?

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  • DBnull in Linq query causing problems

    - by nat
    hi there i am doing a query thus: int numberInInterval = (from dsStatistics.J2RespondentRow item in jStats.J2Respondent where item.EndTime > dtIntervalLower && item.EndTime <= dtIntervalUpper select item).count(); there appear to be some dbnulls in the endtime column.. any way i can avoid these? tried adding && where item.endtime != null.. and even != dbnull.value do i have to do a second (first) query to grab all that arent null then run the above one? im sure its super simple fix, but im still missing it.. as per thanks nat

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  • How can I identify unknown query string fragments that are coming to my site?

    - by Jon
    In the Google Analytics content overview for a site that I work on, the home page is getting many pageviews with some unfamiliar query string fragments, example: /?jkId=1234567890abcdef1234567890abcdef&jt=1&jadid=1234567890&js=1&jk=key words&jsid=12345&jmt=1 (potentially identifiable IDs have been changed) It clearly looks like some kind of ad tracking info, but noone who works on the site knows where it comes from, and I haven't been able to find any useful information from searching. Is there some listing of common query string keys available anywhere? Alternatively, does anyone happen to know where these keys (jkId, jt, jadid, js, jk, jsid and jmt) might come from?

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  • Group by/count in LINQ against SQL Compact 3.5 SP2

    - by bash74
    Hello, I am using LINQ-To-Entities in C# and run queries against a SQL Compact Server 3.5 SP2. What I try to achieve is a simple group by with an additional where clause which includes a Count(). var baseIdent="expression"; var found=from o in ObservedElements where o.ObservedRoots.BaseIdent==baseIdent group o by o.ID into grouped where grouped.Count()==1 select new {key=grouped.Key, val=grouped}; foreach(var res in found){ //do something here } This query throws the famous exception "A parameter is not allowed in this location. Ensure that the '@' sign and all other parameters are in a valid location in the SQL statement." When I either omit the where clause OR directly enter the expression "expression" in the query (where o.ObservedRoots.BaseIdent=="expression") everything just works fine. Does anybody know how to solve this? Workaround would also be fine? Thanks in advance, Sebastian

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  • Linq query with subquery as comma-separated values

    - by Keith
    In my application, a company can have many employees and each employee may have have multiple email addresses. The database schema relates the tables like this: Company - CompanyEmployeeXref - Employee - EmployeeAddressXref - Email I am using Entity Framework and I want to create a LINQ query that returns the name of the company and a comma-separated list of it's employee's email addresses. Here is the query I am attempting: from c in Company join ex in CompanyEmployeeXref on c.Id equals ex.CompanyId join e in Employee on ex.EmployeeId equals e.Id join ax in EmployeeAddressXref on e.Id equals ax.EmployeeId join a in Address on ax.AddressId equals a.Id select new { c.Name, a.Email.Aggregate(x=x + ",") } Desired Output: "Company1", "[email protected],[email protected],[email protected]" "Company2", "[email protected],[email protected],[email protected]" ... I know this code is wrong, I think I'm missing a group by, but it illustrates the point. I'm not sure of the syntax. Is this even possible? Thanks for any help.

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  • DB4o Linq query - How to check for null strings

    - by Dave
    Hey there - simple query: var q = (from SomeObject o in container where o.SomeInt > 8 && o.SomeString != null //Null Ref here select o; I always get a null reference exception. If I use String.IsNullOrEmpty(o.SomeString) the query takes about 100 times as long, as if I use && o.SomeString != "" (which is way faster, but obviously not correct). I'm guessing because DB4o needs to activate the objects, in order to pass them in to the IsNullOrEmpty call, and can't use the indexes. My question is, what's a better way to check for nulls in this situation? Is there something like: mystring != Db4o.DBNull.Value, or something? Cheers, Dave

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  • insert array to mysql db function

    - by ganjan
    Hi. I have an array where the keys represent each column in my database. Now I want a function that makes a mysql update query. Something like $db['money'] = $money_input + $money_db; $db['location'] = $location $query = 'UPDATE tbl_user SET '; for($x = 0; $x < count($db); $x++ ){ $query .= $db something ".=." $db something } $query .= "WHERE username=".$username." ";

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  • Multiple Table Join in Linq C# Dynamically

    - by kmkperumal
    I have 3 data table a,b,c In this I need to write Join Query Dynamically using linQ. The Selecting columns given by customer and Condition columns also given customer at run time. So i need to create Querys dynamically.Please check below example.Because i dont which table they want and which column also For example Select a.c1,a.c2,b.c1,b.c2 From a Left Join b on a.c1=b.c1 2.Select c.c1,c.c2,a.c1,a.c2 From c Left Join a on c.c3=a.c1 3.Select a.c1,a.c2,b.c1,b.c2,c.c1,c.c2 From a Left Join b on a.c2=b.c2 Left join c on c.c1=a.c1 Like i need create different set of query's. Please help me on this.

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  • MySQL query optimization - distinct, order by and limit

    - by Manuel Darveau
    I am trying to optimize the following query: select distinct this_.id as y0_ from Rental this_ left outer join RentalRequest rentalrequ1_ on this_.id=rentalrequ1_.rental_id left outer join RentalSegment rentalsegm2_ on rentalrequ1_.id=rentalsegm2_.rentalRequest_id where this_.DTYPE='B' and this_.id<=1848978 and this_.billingStatus=1 and rentalsegm2_.endDate between 1273631699529 and 1274927699529 order by rentalsegm2_.id asc limit 0, 100; This query is done multiple time in a row for paginated processing of records (with a different limit each time). It returns the ids I need in the processing. My problem is that this query take more than 3 seconds. I have about 2 million rows in each of the three tables. Explain gives: +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+----------------------------------------------+ | 1 | SIMPLE | rentalsegm2_ | range | index_endDate,fk_rentalRequest_id_BikeRentalSegment | index_endDate | 9 | NULL | 449904 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | rentalrequ1_ | eq_ref | PRIMARY,fk_rental_id_BikeRentalRequest | PRIMARY | 8 | solscsm_main.rentalsegm2_.rentalRequest_id | 1 | Using where | | 1 | SIMPLE | this_ | eq_ref | PRIMARY,index_billingStatus | PRIMARY | 8 | solscsm_main.rentalrequ1_.rental_id | 1 | Using where | +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+----------------------------------------------+ I tried to remove the distinct and the query ran three times faster. explain without the query gives: +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+-----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+-----------------------------+ | 1 | SIMPLE | rentalsegm2_ | range | index_endDate,fk_rentalRequest_id_BikeRentalSegment | index_endDate | 9 | NULL | 451972 | Using where; Using filesort | | 1 | SIMPLE | rentalrequ1_ | eq_ref | PRIMARY,fk_rental_id_BikeRentalRequest | PRIMARY | 8 | solscsm_main.rentalsegm2_.rentalRequest_id | 1 | Using where | | 1 | SIMPLE | this_ | eq_ref | PRIMARY,index_billingStatus | PRIMARY | 8 | solscsm_main.rentalrequ1_.rental_id | 1 | Using where | +----+-------------+--------------+--------+-----------------------------------------------------+---------------+---------+--------------------------------------------+--------+-----------------------------+ As you can see, the Using temporary is added when using distinct. I already have an index on all fields used in the where clause. Is there anything I can do to optimize this query? Thank you very much!

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  • PHP: MySQL query duplicating update for no reason

    - by ThinkingInBits
    The code below is first the client code, then the class file. For some reason the 'deductTokens()' method is calling twice, thus charging an account double. I've been programming all night, so I may just need a second pair of eyes: if ($action == 'place_order') { if ($_REQUEST['unlimited'] == 200) { $license = 'extended'; } else { $license = 'standard'; } if ($photograph->isValidPhotographSize($photograph_id, $_REQUEST['size_radio'])) { $token_cost = $photograph->getTokenCost($_REQUEST['size_radio'], $_REQUEST['unlimited']); $order = new ImageOrder($_SESSION['user']['id'], $_REQUEST['size_radio'], $license, $token_cost); $order->saveOrder(); $order->deductTokens(); header('location: account.php'); } else { die("Please go back and select a valid photograph size"); } } ######CLASS CODE####### <?php include_once('database_classes.php'); class Order { protected $account_id; protected $cost; protected $license; public function __construct($account_id, $license, $cost) { $this->account_id = $account_id; $this->cost = $cost; $this->license = $license; } } class ImageOrder extends Order { protected $size; public function __construct($account_id, $size, $license, $cost) { $this->size = $size; parent::__construct($account_id, $license, $cost); } public function saveOrder() { //$db = Connect::connect(); //$account_id = $db->real_escape_string($this->account_id); //$size = $db->real_escape_string($this->size); //$license = $db->real_escape_string($this->license); //$cost = $db->real_escape_string($this->cost); } public function deductTokens() { $db = Connect::connect(); $account_id = $db->real_escape_string($this->account_id); $cost = $db->real_escape_string($this->cost); $query = "UPDATE accounts set tokens=tokens-$cost WHERE id=$account_id"; $result = $db->query($query); } } ?> When I die("$query"); directly after the query, it's printing the proper statement, and when I run that query within MySQL it works perfectly.

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  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

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  • Linq to SQL Strange SQL Translation

    - by Master Morality
    I have a simple query that is generating some odd SQL translations, which is blowing up my code when the object is saturated. from x in DataContext.MyEntities select new { IsTypeCDA = x.EntityType == "CDA" //x.EntityType is a string and EntityType.CDA is a const string... } I would expect this query should translate to: SELECT (CASE WHEN [t0].[EntityType] = @p1 THEN 1 ELSE 0 END) as [IsTypeCDA] ... Instead I get this : SELECT (CASE WHEN @p1 = [t0].[EntityType] THEN 1 WHEN NOT (@p1 = [t0].[EntityType]) THEN 0 ELSE NULL END) AS [IsTypeCDA] ... Since I'm saturating a POCO where IsTypeCDA is a bool, it blows up stating I can't assign null to bool. Any thoughts? Edit: fixed the property names so they make sense...

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