Multi - Table Join Query In ASP.NET To SQL Server Via LINQ?
Jan 29, 2012
I'm working on an ASP.NET 4.0 site, which I inherited ownership of. It has a number of existing LINQ datasources pointing to individual tables. For example, to the Patient Encounter Summary table in SQL Server. The problem is in displaying the data there. It's a normalized database, so that table contains (for example) the provider ID, rather than the provider name.
It's simple enough to join the Patient Counter Summary to the Providers table (in SQL)... but how does one do that in ASP.NET? I'm not sure of the correct nomenclature, but the 'mid layer' is VB.
[Code]...
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Aug 6, 2010
Given a table like
ID | Name | City
1 | X | Y
2 | Z | Y
[code].....
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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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Aug 23, 2010
I have two tables Employees and CafeLogs. Some employees can be cashiers and also customers at the Cafe shop.
Table structures:
Employees: EmployeeId(PK) , FirstName, LastName
CafeLogs: LogId (PK), CashierId, EmployeeId, Value, => CashierId and EmployeeId are the data from column EmployeeId of Empoyee table
Table relationship:
Employees 1:N CafeLogs (CashierId (FK))
[code]....
Right now I know how to select only LogId, Employee's name, and , Value, not with Cashier name yet.
Dim query = From log In db.CafeLogs _
Join emp In db.Employees On emp.EmployeeId Equals log.EmployeeId _
Select log.LogId, emp.FirsName, emp.LastName, log.Value
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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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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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Dec 6, 2009
I have a set of LINQ queries filtering original datatable (loaded from Excel file) based on user selections in Comboboxes. Then the result is joined with Arraylist to further filter the set. Arraylist is a simple list of strings.
Query:
If (Samples.Item(0) Is Nothing) = False And Samples.Item(0) <> "All samples" Then
queryResults = From records In queryResults Join samp In Samples _
On records("SAMPNUM") Equals samp _
[Code]....
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Apr 17, 2011
How to JOIN tables on nullable columns? I have following LINQ-query, RMA.fiCharge can be NULL:
Dim query = From charge In Services.dsERP.ERP_Charge _
Join rma In Services.dsRMA.RMA _
On charge.idCharge Equals rma.fiCharge _
Where rma.IMEI = imei
Select charge.idCharge
I get a "Conversion from type 'DBNull' to type 'Integer' is not valid" in query.ToArray():
Dim filter = _
String.Format(Services.dsERP.ERP_Charge.idChargeColumn.ColumnName & " IN({0})", String.Join(",", query.ToArray))
So I could append a WHERE RMA.fiCharge IS NOT NULL in the query. But how to do that in LINQ or is there another option?
The problem was that the DataSet does not support Nullable-Types but generates an InvalidCastException if you query any NULL-Values on an integer-column. The modified LINQ-query from dahlbyk works with little modification. The DataSet generates a boolean-property for every column with AllowDbNull=True, in this case IsfiChargeNull.
Dim query = From charge In Services.dsERP.ERP_Charge _
Join rma In (From rma In Services.dsRMA.RMA _
Where Not rma.IsfiChargeNull
Select rma)
On charge.idCharge Equals rma.fiCharge _
Where rma.IMEI = imei
Select charge.idCharge
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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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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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May 18, 2012
I am starting with Linq to SQL in VB.NET, and trying to figure out how to make a simple query to a database.I want to do it all programaticly.I have made a connection to the database with a connectionstring, and this works fine - I can get a message if the database exists or not.But when I want to query a table, I am missing the part where I connest to the table. I have googled a lot to find an answer for thi, but [code]
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Sep 2, 2009
I was able to use it for querying out info from an XML file but now i have to use the DBF file from a folder. where i can find out how to query out DBF table using LINQ. I basically need to get data from a column of a DBF table.
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Feb 23, 2011
I have a query that I have to run that requires me to get rows from a table based on the value of a field in another table (which I have gotten earlier). I currently have it done like this (simplified).
[Code]...
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Apr 26, 2010
I have 2 tables Table1 with columns [BId,Name,Amount] Table2 with columns [CId,BId, ExpenseType,Expense]. BId Is the foreign key in Table2. The Amount field in Table1 is always higher than Expense in Table2. I need to update the values of Amount (increase or decrease) based on value of Expense and I want to do it in single query in LINQ. Eg If the Expense has to be updated with 200, I would decrease(negate) Amount value with 200. If Expense is reduce to 100 then the Amount is increased by a value of 100.
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Jul 9, 2010
I have a table (Projects) which is linked to projectVersions on projectID..projectVersions contains several columns on which I'd like to filter a returned project (and associated projectVersions) list. For example there is a "capacity" column and a "country" column. I am doing a filtered list of projects on one page and I'd like to include all projects where any one of the associated projectVersions has a capacity of 750ml and a country of "France" for example.It may be that a particular parameter is not set and so I pass a zero to indicate not to filter on that.I guess this needs some kind of subquery as when I try and do something like this: [code] it doesn't work as the "xxx" bit, being one-to-many, expects me to specify an item to get at the entities within and yet I want to query where ANY of the associated versions match one of the criteria.
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Mar 2, 2011
I have 2 Tables , OrderDetails and Requests In my LINQ to SQL dbml file. OrderDetailsID is a foreign key in Requests Table.
I want to write the query to get the sum of UnitCost from OrderDetails based on OrderId. And If there is a row in Requests Table for each OrderDetailsID, and the Requests.Last.RequestType="Refund" I want to reduce the total refund amount from the main sum otherwise If there is no row based on OrderDetailsID, add to sum.
Here is the way I implement that. I am looking to prevent using "For each".
iRefund = (From od1 In dc.OrderDetails _
Where od1.OrderID =1 _
Select od1.UnitCost).Sum
[Code]....
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Mar 4, 2009
I have 2 Tables , OrderDetails and Requests In my LINQ to SQL dbml file.OrderDetailsID is a foreign key in Requests Table.I want to write the query to get the sum of UnitCost from OrderDetails based on OrderId.And If there is a row in Requests Table for each rderDetailsID, and the Requests.Last.RequestType="Refund" I want to reduce the total refund amount from the main sum otherwise If there is no row based on OrderDetailsID, add to sum
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Feb 8, 2011
Is there a way to use Meta Tales or Table names to Construct a dynamic query in LINQ?
foreach (var metaTable in db.Mapping.GetTables())
{
var queryType = metaTable.RowType.Type;
[code]....
Is there a way to do something like this? The attempt above yields the error:Could not find an implementation of the query pattern for source type 'System.Data.Linq.ITable'. 'Select' not found. Consider explicitly specifying the type of the range variable 'q'.
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Jun 7, 2011
I'm trying to query old Access database tables and compare them with SQL Server tables.They often don't have primary keys, or they have extra fields that had some purpose in the nineties, etc., or the new tables have new fields, etc.I need to find records - based on a set of fields specified at runtime - that are in one table but not another.So, I do this kind of query all the time in SQL, when I'm comparing data in different tables:
dim fields_i_care_about as string = "field1, field2, field3"
'This kind of thing gets set by a caller, can be any number of fields, depends on the
'table
dim s as string= ""
[code]....
It tells me it can't convert a Boolean - Is there any way to do this without Linq expressions? They seem far more complex than what I'm trying to do here, and they take a lot of code, and also I can't seem to find examples of Expressions where we're comparing two fields in a subquery.Is there a simpler way? I know I could do the usual EXISTS query using JOIN or IN - in this case I don't need the query to be super fast or anything. And I don't need to use a DataTable or DataSet - I can put the data in some other kind of object.
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Apr 13, 2012
I am trying to create a CLR SQL Stored procedure that uses a query and adds the results to a list in VB.NET. Through debugging I determined that my add statement for the reader into the List is somehow converting my data types and throwing an error when I attempt to execute the compiled Stored Procedure.The columns I am querying are Integers
Code:
Imports System
Imports System.Data
[code].....
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Sep 22, 2009
I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.
For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.
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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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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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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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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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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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