Asp.net - Avoid Error When No Results From Entity Query?
Mar 14, 2011
I have a simple Entity query:
Dim rhcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "rhc" _
Order By p.ID Descending _
Select p
I then check whether one of the result values is more recent than six months ago using an if..then like so:
If rhcexists.First.SignatureDate > Date.Today.AddMonths(-6) Then End If
However, if there are no results returned this will return an error. Is there a way for me to tell it to act as if the date is older than six months if there is no value at all? e.g., could I in pseudo do something like:
If Exists(rhcexists.First.SignatureDate, Date.Today.AddMonths(-8)) > Date.Today.AddMonths(-6) Then End If
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Oct 10, 2010
I have a query that will go away an and find data
Dim HSNs As String = String.Join(",", ListOfHSNs.Cast(Of String)().ToArray())
Dim query As String = "SELECT VALUE O FROM v_BillData AS O WHERE O.HSNumber IN {'" & HSNs & "'}"
Dim hs As New ObjectQuery(Of v_BillData)(query, CType(Session("ObjectCon"), ObjectContext))
What I now wish to do is to use the results of this query to databind to a EntityDataSource?
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Apr 9, 2011
I have the following LINQ-to-Entities query:[code]This will give me all the resident assignments for the current year/term. Then I have this LINQ-to-Entities query:[code]This will give me all the rooms. I want to iterate through the assignments and based on what room is assigned update the occupancy in reset_occupancy. I'm not 100% sure how to accomplish this. Here is my pseudo code of what I want to accomplish:[code]
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Dec 15, 2009
I have the following LINQ-to-Entities query:
' Get all the residency assignments that match the term/year.
Dim assignments = From p In dbContext.Residents _
Where p.semester = term _
[code].....
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Mar 14, 2011
I have a simple If..Then like so:
If rhcexists.First.SignatureDate > Date.Today.AddMonths(-6) Then
End If
rhcexists is a simple query to the Entity Model:
[code].....
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Apr 29, 2012
I'm receiving an error when trying to query a range of dates from a MS SQL DB in MVC Entity Framework. Unable to cast the type 'System.Boolean' to type 'System.Data.SqlTypes.SqlBoolean'. LINQ to Entities only supports casting Entity Data Model primitive types. This is our query:
[Code]...
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Sep 6, 2010
how to replace the html code numbers with the correct ones? i would show you example of html output, but vbforum automatically converts the characters so no point. i wish the replace all the & #40; (without the space) and so on with their correct replacement eg, ( in this case. also would like a short way to do this as i will be using this multiple times. so basically i would like the source to be exactly as it would if you viewed source in firefox browser, not with all the special chars unformatted like visual studio does.
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Mar 11, 2010
how to take a query that returns a single row of data and load that data into textbox controls.I know about ExecuteScalar but it is only good for a single column of data from the query.
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May 10, 2012
I'm trying to use the Entity Framework to create a complex query and get stuck in the joins. After browsing some of the documentations, I cannot seem to find the correct solution, so maybe someone here can help.
I have a data structure where a family has several family members, each of which can have more than one entry in the income table (on different registration dates) and can have more than one entry in the healthconditions table.
[Code]...
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Apr 7, 2011
I'm triying to create a dynamic query to Entity FW (i'm using Self tracking Entities over EF)
This is what i'm doing:
Public Class Specification(Of TEntity As Class)
Private _predicado As Expression(Of Func(Of TEntity, Boolean))
Public Sub New(ByVal columna As String, ByVal condicion As OperadoresComparacion, ByVal valor As Object)
[Code].....
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Apr 9, 2011
I have the following code:
' Now retabulate the current occupancy.
For Each row In assignments
Try
[code]....
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Jan 4, 2011
I have a view on some data in my database it returns the data as I would expect, for example
Call Date To From Phone Number
20/1/2010 00:00 23:59 08923233223
20/1/2010 00:00 23:59 08923233245
However when I have added this to my Entity Model and query it I get duplicate(and unexpected) data appearing
Call Date To From Phone Number
20/1/2010 00:00 23:59 08923233223
20/1/2010 00:00 23:59 08923233223
I am simply binding a Entity Data Source to this Entity but I am left scratching my head as to why the data is being returned differently
EDIT: Interestingly this can't be the result of some strange under the hood join as the row counts match as expected. I have also put together a query myself to test with the same odd results.From o In App.Entities.v_PersonalRules Where o.companyid = CompanyID Select o. I am using Visual Studio 2010, .NET 4
EDIT: The front end code is fairly simple
<asp:EntityDataSource ID="EDS_Personal" runat="server" ConnectionString="name=Entities_NEW"
DefaultContainerName="Entities_NEW" EnableDelete="True" EnableInsert="False"
EnableUpdate="True" EntitySetName="v_PersonalRules" EntityTypeFilter="v_PersonalRules" >[code]....
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Dec 22, 2011
I have Customers table in a database. I'd like to create List of CustomerNames using entity framework 4.1. How can I do that in Visual Basic?
Dim customerNames = (From c In _context.Customers
Select New With {c.CustomerName}).ToList()
brings a list of anonymous objects.
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Aug 31, 2011
This is my first time using the Entity Framework and I'm getting some confusing results. I know a particular table contains 3 distinct rows when I run this SQL query:
SELECT * FROM mytable WHERE service_month = 201012
When I run this query against the framework however, I get 3 rows, but they are all copies of the first row (VB syntax).
Dim temp = _context.mytable.Where(Function(x) x.service_month = 201012)
Did I set up something incorrectly? This is how I'd do it with LINQ to SQL.
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Oct 18, 2010
I have a the following setup
m_handsets = From p In RL.App.TComEntities.tblTelephoneNumbers _
Where p.companyId = m_CompanyID _
Select p
m_handsets = DirectCast(m_handsets, ObjectQuery(Of RL.TelephoneNumbers)).Include("tblCalls")
where m_handsets is defined as Private m_handsets As IQueryable(Of RL.tblTelephoneNumbers)
which works as expected however what I want to do know is query the Navigation property (tblCalls) so I can do something like the following From p In m_handsets.tblCalls Where m_handsets.tblCalls.price > 100
I think the complexity comes here because in this instance I could have 5 tblTelephoneNumbers in m_handsets and then x amount of calls for that particular telephone number. I am interested in the tblCalls for each but I would like to filter them all for each tblTelehoneNumber.
Entity Diagram which (hopefully) should illustrate further So I currently know all the handsets that are associated with the company I am interested in. I can also see the calls loaded as a navigation property in debug mode, but I want to say is take this filter (in this example price>100 and apply it to all handsets->calls
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Mar 15, 2011
I have setup an OleDbConnection and my query works just fine but the problem I am facing is that I want the entire query not just a certain row or column. I also would like to place this entire query into a blank excel spread sheet.[code]
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Feb 3, 2009
If this is in the wrong section, I have a program that queries a database and puts the info in a specific format in a txt file. Now my problem comes w/ how to format the date.
Should I format the date in the SQL query OR is there a way to take the result from the query and format sometime before it is writen to the txt file? I'm not exactly sure how to do either. Would I need a subquery to get the desired date format?
[Code]...
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Apr 22, 2009
I am using an access DB and wanted to create a query that returns user's in the db. First I need to check the db to see if it is empty. Then I need to check to see it my query returned any values. How do I go about doing this?
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May 8, 2011
I'm a bit confused on how to grab query results. With VBA i would open a record set and have the results of the query written to that recordset. IN VB.net how can I grab the query result and throw each column into specfic arrays?[code]Now how would I force it to query my DB? I have a connection established already.After the query how can i play with the columnes and place them into arrays?
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Sep 11, 2009
I have used linq quite abit but was just wondering how to append the results of two IEnumerable(of X) together into one IEnumerable(of X)
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Aug 22, 2011
I had this query sp_msforeachdb 'select "?" AS db, * from [?].sys.tables' when I execute it in sql server, it return multiple results. How I can read all the results in my vb?
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Oct 5, 2011
I have the following code in my program: Dim empenrollments = From enroll In db.EnrollmentSummary(eid)
Select New With {.Name = ename, enroll} Dim elist = empenrollments.ToList returns this error
In the following lines, I have to get each row in the returned results and add it to a DataTable, but it never gets there.
[Code]...
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Feb 27, 2009
I am familiar with the VB6 ADO way of dealing with SQL queries and looping through the record set results.
However, what is the correct way to query a server, cycle through the results, and dispose of my query in VB.Net? All the ways I have been using seem to be unstable and crash randomly.
I have been using the following code:
Public Function GetSQLTable(ByVal strSQL As String) As DataTable
Dim table As New DataTable
Dim adapt As SqlDataAdapter
[Code].....
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Apr 9, 2012
I am learning VB.NET and wanted to try and connect to a Oracle.DataAccess with this simple SQL Query but am stuck how to get my results.
Imports Oracle.DataAccess.Client
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click[code].....
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May 31, 2012
I'm trying to get the results of a WMI to display in a datagrid however the code executes without error yet the datagrid doesnt show any output
Try
Dim scope As New ManagementScope("\" & servername & "
ootMicrosoftDFS")
[code].....
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Jan 9, 2009
I'm trying to execute a SQL query and pull the results into a text file. However, I'm getting an error in the bolded part. I think probably the biggest help would be an explaination of what the code in bold is actually doing. I pulled this from a book but don't think I completely understand. To me it seems like its saying that for each row in table 'extract'. Extract it, and write it?? But it doesn't seem to work that way. When it gets to that part, the error I get says that the row doesn't exist in the table
Private Sub btnExecute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExecute.Click
Cursor.Current = Cursors.WaitCursor 'hourglass cursor
Dim connection As New SqlConnection
[code]....
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Mar 5, 2011
I have a query using LINQ-to-SQL. It queries an underlying database table Rooms. It uses Where conditions to narrow down the results, namely:
Gender.Current Occupancy < Max Occupancy Available Flag is Checked I know this should return results but it keeps returning an empty set.Code is below
[code]...
UPDATE: I've verified that the issue is with the statement where sh.is_available = 1, which doesn't make sense since this is a bit field.
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Jul 10, 2009
Why would a VB/ASPX page not return results for a query which runs fine with other Oracle clients? (Same username) The following code should first output the query and then execute it outputting a single exclamation point per record. However, it outputs the query (as it should), but does not return any rows (nor error). If I copy the query to SQL Plus (or other editor) as the same user, the query returns results.
Why might my code not output any results?
Dim MyQuery As String = "...some query..."
Dim Factory As DbProviderFactory = DbProviderFactories.GetFactory("System.Data.OracleClient")
Dim myConn As DbConnection = Factory.CreateConnection
Dim myCommand As DbCommand = Factory.CreateCommand
Dim MyReader As DbDataReader
[Code]...
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Feb 23, 2010
I am getting stuck on this problem. It seems simple but for some reason im having trouble.
Here is what I have of the following:
Try
cn = New OleDbConnection("Provider=microsoft.Jet.OLEDB.4.0;Data Source=G:SeanBMSBonder3_0.mdb;")
[Code]....
This works to get only one of the values. Actually the last. how can i get all of them?
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Nov 21, 2011
I have a basic question about using a database with Visual Basic.I'm using a OleDb connection. I have dragged and dropped editboxes from the DataDource view. This automatically places the table navigation- bar on the form. When I run it this works fine.However I want to be able to search within the table, with an SQL statement.How can I connect the results from the SQL query to the navigation bar,such that the editboxes automatically take the values of the record without having to assign every textbox manually?
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