C# - Linq To Objects Outer Join?
Mar 10, 2010
Im trying to use LINQ to query Objets. I'm doing the following:
Dim myList As Generic.List(Of MyItem) = (From ThisItem In LinqToSqlObject.Items _
Join Folder In LinqToSqlObject.Folders _
On Folder.Id Equals Item.Id _
[Code]....
This however will not return any item that has a ParentItemId of null. I am trying to do a left join so as to return all "Item" regardless of whether it has a parent or not. I am aware that this is feasible in C# by adding an "into X" on the join, and selecting from X.DefaultIfEmpty(), this however does not appear to work in VB.Net.
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Apr 21, 2011
I ultimately what I needed is generic function which would take two datatable and and 2 tablekeys and return Joined datatable. So here is my first step to solve it.
How Can I write Linq example of following T-SQL example in VB?
SELECT * FROM
Table1
LEFT OUTER JOIN
Table2
ON Table1.key = Table2.key
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Nov 9, 2011
I cannot get this to work with LINQ to SQL vb.net?
SELECT a.FLD_ID, a.FLD_SUBJECT, a.FLD_GROUP, a.FLD_SUBMITTED, a.FLD_LASTACTION, a.FLD_CLOSED
FROM TBL_WSS_TT_TICKET a LEFT OUTER JOIN
TBL_WSS_TT_ALLOW b ON a.FLD_ID = b.FLD_TICKET_REF
WHERE (a.FLD_USER = 'user') OR (b.FLD_USER = 'user')
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Mar 25, 2011
I am using Subsonic3 and would like to get a Left Outer Join between two tables. Here is the tested SQL
SELECT a.*
FROM vwVendor a
LEFT OUTER JOIN dbo.pubvenmap b
on a.vend_no = b.vend_no
where b.vend_no is null
[Code]...
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Sep 27, 2010
I've got what I think is a working left outer join linq query but I'm having problems with the select because of null values in the right hand side of the join.[code]I want to return all of e and one column from c called tClassCode. I was wondering what the syntax would be. As you can see I'm using vb.net.[code]If i remove the c.tClassCode from the select the query runs without error. So i though perhaps i needed to do a select new but i don't think i was doing that correctly either.
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Jul 4, 2009
I've looked all around and spent way to long trying to convert this SQL statement into a Linq statement in VB. I'm sure it would be a good example for others out there - the statement is trying to pull products that have a many-to-many relationship with product categories, and the categories have a hierarchy of parents/children.
Here is the query I am trying to convert:
SELECT P.ProductID, P.ProductName, P.ProductSlug, P.PartNumber
FROM Products AS P
INNER JOIN Products_Categories AS PC ON PC.ProductID = P.ProductID
[code]....
I can get up to the point where I am trying to say "WHERE ... (P_Cats.Parent = 9)" but can't figure that part out.
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Oct 18, 2010
how to translate a simple SQL LEFT OUTER JOIN with a two condition where clause into a working Linq-to-Entities query. There are only two tables. I need values for all rows from Table1, regardless of matches in Table2, but the WHERE clause uses fields from Table2. In SQL, the two parameters would be Table2WhereColumn1 and Table2WhereColumn2, and the query (which works) looks like this:
SELECT t1.Table1Id,
t1.FieldDescription,
t2.FieldValue
[code].....
I've tried using Group Join with DefaultIfEmpty(), as well as an implicit join (without the actual Join keyword), and I only get rows for items that have values in Table2. I'm sure this won't help, but here's an example of the Linq I've been trying that doesn't work:
Public Shared Function GetProfilePreferencesForCedent(ByVal dc As EntityContext, _
ByVal where1 As Int32, _
ByVal where2 As Int32) _
[code].....
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Apr 29, 2010
i'm having troubles with a linq-to-sql statement and getting a left outer join to work. here is a sample of two tables i'm trying to join and my code that i've wrote.
Table1 Table2
f1 f2 f3 f4 fID f1 f2 f3 f4
val1 val2 val3 val4 1 val1 val2 val3 val4
[code]....
Instead I'm returning ALL values from table 1. I need to return all values from the left outer join where tbl2.fID is null.
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Feb 4, 2011
I have two tables, a LP_task table and an lp_Update table. I want a complete list of tasks and only updates that were posted during a specific date range. LINQ doesn't seem to support any other join criteria but 'equals'or each task. I want all tasks (left table) even if they don't have an update. (Left Outer Join)
Dim TasksData = (From t In db.LP_Tasks _
Group Join up In db.LP_Updates On t.ID Equals up.TaskID Into upds = Group _
From u In upds.DefaultIfEmpty _
[code]......
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Dec 15, 2011
How to Join the objects in a LINQ select in this sample (C# variants accepted as well):
Class Room
Public Area As Integer
End Class
Class RoomPair
[code]....
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May 12, 2010
I am new to ado.net and I am trying to learn capabilities as much as get this particular task done.Let me set the stage for my question.My goal is to load up a dataset, write out an XML, transfer the file to another machine, read the XML back into a data set, load up the local tables, find missing records from the local database and add them.These tables are for employees. There is the 'Employee' master, "Employee Job" the employee job code, and "Employee Hours", the employee time punches.I thought I could treat a dataset as a database and do SQL queries against it.For example to find missing Employee , my thought was to do a outer join on employeeID and look for null in the second table.Something like:
[Code]...
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Jun 27, 2011
Basically what I'm having to do is create a program that takes a list of CaseIDs and compares them to a table on a remote SQL server. However, the table holding the CaseIDs on the remote server has nearly 120,000 records.
Currently my plan is to query all records on the remote server, save the query and the current list to tables in an Access DB file and then run an outer join to see which CaseIDs have no matching records on the remote server.
I believe this will be a much slower process than I would like. If I could load both queries into arrays or lists in VB and then compare them (therefore, not having to write 120,000 records to a DB file), it would be much faster.
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Aug 9, 2011
I am using/creating a DataTable so the "enforceConstrains" property is not avilable for DataTable.Error message: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.
Windows Form Load Event:
Private Sub Expenses_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
expensesGV.DataSource = listExpenses()
expensesGV.Columns(0).Visible = False
End Sub
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Apr 15, 2011
I'm trying to join two datatables of same keyfields.
table1
ID Class
---- -----
1 10
2 9
[code]....
Result
ID Class1 Class2
1 10 8
2 9 7
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Sep 28, 2011
I have this query that I tried to join 2 tables together, one which holds the product name, and product numbers, and take a product number, and go to the other where to find a Art_no which is like the product number.[code]
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Apr 23, 2009
Given two tables, customer and orders, how would one do a linq query to entities to find any customers with open invoices started before a certain date?
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Jan 13, 2011
I have two DataTables:
dt1 - personid, name
dt2 - personid
I want to create a third datatable to include records from dt1 when they are NOT in dt2 using LINQ. In this case, I can bind the third datatable to a dropdownlist.
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Jun 16, 2009
Are the below two queries functionally the same?The first one doesn't return any data, but the second works fine with same exact input.Can someone point out what's wrong in my first query? [code]
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Jul 8, 2010
How would I perform this SQL query
Select Distinct s.*
from #ScopeIDs x
Join Scopes s on s.ScopeID=x.ScopeID or x.ScopeID is null
in LINQ to SQL? (This query would return all Scopes whose ScopeID is present in #ScopeIDs, unless one of the entries in #ScopeIDs is null, in which case it returns all Scopes).
A "literal" translation doesn't work, since LINQ doesn't support joining with multiple conditions - code along these lines ...
From x in ScopeIDs
Join s in Scopes on s.ScopeID equals x.ScopeID or x.ScopeID equals nothing
Distinct Select s
... doesn't compile.
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Apr 11, 2011
I can't figure out that linq to entity query syntax. My problem is that if the value of the Calls table is null then noting comes up, I want to make something like a left join to get 'all' rows from the Calls table.I tried to group it but I can't figure out the correct way to write it.
Dim TicketQuery As ObjectQuery = From c In EnData.Customer _
Join t In EnData.Calls On t.CustomerID Equals c.CustomerID _
Join Status In EnData.Lists On t.Status Equals Status.ListValue _
[code].....
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Jun 14, 2012
i think i have not represented my question correctly here My LEFT OUTER JOIN MSDN reference is here to visualize my problem in access databaseTABLE "T1"1234567TABLE "T2"1,sunday2,monday i need output as 1,sunday2,monday34567 i need it to done through LINQso far i did is here
Dim RIGHT_table As DataTable = ds1.Tables("t1")
Dim LEFT_table As DataTable = ds2.Tables("T2")
Dim OutPut = From LEFTsource In LEFT_table.AsEnumerable(), RIGHTsource In RIGHT_table.AsEnumerable() _
[code]...
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Sep 9, 2010
I'm trying to LINQ two tables based on a dynamic key. User can change key via a combo box. Key may be money, string, double, int, etc. Currently I'm getting the data just fine, but without filtering out the doubles. I can filter the double in VB, but it's slooooow. I'd like to do it in the LINQ query right out of the gate.
[Code]...
"Range variable name can be inferred only from a simple or qualified name with no arguments."
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Jun 9, 2011
I'm trying to LINQ two tables based on a dynamic key. User can change key via a combo box. Key may be money, string, double, int, etc. Currently I'm getting the data just fine, but without filtering out the doubles. I can filter the double in VB, but it's slooooow. I'd like to do it in the LINQ query right out of the gate.
LinqMasterTable:
-------------------------------------------------------------
| AppleIndex | AppleCost | AppleColor | AppleDescription |
------------------------------------------------------------
[Code].....
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Apr 23, 2009
Let's say I have Plans and Documents
Dim myPlans = _context.Plans.Where(predicate1)
Dim myDocuments = _context.Documents.Where(predicate2)
I have structured the where clause for each using PredicateBuilder. So, myPlans and myDocuments have a correct SQL statement. What I'd like to do is join these two tables into one linq statement. The problem I'm having is that, by default the AND condition is joining the where clauses.
myPlans Where clause : (p.name like "%test%" AND p.name like "%bed%") OR (p.description like "%test%" AND p.description like "%bed%")
myDocuments Where clause : (d.name like "%test%" AND d.name like "%bed%") OR (d.description like "%test%" AND d.description like "%bed%")
When I combine the two the desired result Where clause is:
Where (d.ID = p.ID) AND
(myplans where clause above) OR (mydocument where clause above). Meaning, I'd like the two where clauses in each of the tables to be "or" instead of "And".
The current result where clause is:
Where (d.ID = p.ID) AND
(myplans where clause above) AND (mydocument where clause above). Meaning, I'd like the two where clauses in each of the tables to be "or" instead of "And".
I'm forming the statement like this:
Dim test = From d in myDocuments _
Join p in MyPlans on d.ID Equals p.ID _
Select d.Name, p.Name
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Apr 19, 2010
I'm having trouble with a LINQ to SQL query getting the min value using Visual Basic. Here's the SQL:
SELECT RC.AssetID, MIN(RC.RecCode) AS RecCode, JA.EngineerNote from JobAssetRecCode RC
JOIN JobAssets JA ON JA.AssetID = RC.AssetID AND JA.JobID = RC.JobID
WHERE RC.InspState = 2 AND RC.RecCode > 0
[code]....
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Nov 10, 2011
I have two UNTYPED datatables: "Shelfs" and "Books". Data came from different databases.
I must create a "left join" relationship because I want a list of ALL shelfs and books (if they have any).
Dim dset As New DataSet
dset.Tables.Add(dtShelfs)
dset.Tables.Add(dtBooks)
[Code].....
I spent hours googling around, but all examples I found were only applicable to strongly typed dataSets, and how to build queries (not to get the data)
I could solve this the "easy" way: by looping both datatables and sending the rows to a third one, but I want to do this the "right" way and, of course... LINQ exists to make things easier and I don't know how to use it
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May 28, 2010
I've long since built a way around this, but it still keeps bugging me... it doesnt help that my grasp of dynamic LINQ queries is still shakey.
For the example:
Parent has fields (ParentKey, ParentField)
Child has fields (ChildKey, ParentKey, ChildField)
Pet has fields (PetKey, ChildKey, PetField)
[Code].....
The above Join call doesnt work. I sort of understand why it doesnt work, but hopefully it'll show you how I tried to accomplish this task.
After all this was done I would have appended a Select to finish the job.
I tried it with the PredicateBuilder with little success. I might not know how to use it right but it felt like it wasnt gonna handle the joining.
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Jun 7, 2011
Here's what I want to do:
Dim queryX = From m In db.Master
Where m.Field = value
Group Join d In db.Detail
On m.Id Equals d.MasterId Into Group
Where d.Field = value
In English, I want to join the master and detail tables, specifying conditions on each. But this causes the following compiler error:
"Name 'd' is either not declared or not in the current scope."
It works if I put this same condition in functional form:
Group Join d In db.Detail.Where(Function(x) x.Field = value)
but I think this is more typing, harder to understand, and introduces that irritating dummy variable. I really would prefer to use the query comprehension syntax. Is there a way to accomplish this?
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Nov 23, 2011
I have used persistance class and used following LINQ query.[code]but it throws an error saying. "Specified Method is not Supported".How can i get data from two table using XPO Persistance Class?
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Dec 5, 2009
I have a set off LINQ queries filtering original datatable (loaded from Excel file) according to user selections in Comboboxes. Then the result is joined with Arraylist to further filter the set. Arraylist is a simple string list from 1 to 5. [Code]
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