.net - Reflecting The Records Created Through Trigger In AssociationAttribute, Linq?
Sep 4, 2011
There is one-to-n relationship (foreign-key relationship) between tables As and Bs. Every time a new record is added in As, a trigger "after update" in table As creates n records in table Bs. There are two Linq-to-SQL classes A and B representing the tables As and Bs respectively.The class A contains Bs property an EntitySet(of B). Similarly in class B, there is a property A, an EntityRef(of A)
[Code]...
When above function is executed the result is always 0. Whereas there are six records new records has been added to table Bs every time the above function is executed.
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Apr 13, 2009
I am trying to figure out out ttrigger a click event from a Picturebox object that is created during runtime? application that I am developing using Visual Studio 2008 during runtime a user selects a shape from a Panel3 on the right side of the form and then clicks on a location inside Panel1 where that shape is copied over. Almost like a Visio application but without the drag and drop.The name of my new shape via a is call "C_Object" I would like the user to be able to select this new shape and a click event to be raised but because this PictureBox object was created during runtime I am not seeing the event.
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Feb 18, 2012
I have a main form that has a dynamically generated treeview and also a panel control. Depending on the selection made within the treeview the panel docks 1 of three diffrent usercontrols which are full sub forms(done for ease of modifing design of sub form rather than layering panels on top of panels).Upon button click withing usercontrol i wish to trigger event within main form.For example delete button wich then triggers to remove current selected node from treeview. code for 1 of three diffrent user controls
Dim ctrlQ As New QuoteUC(TrViewQuotation.SelectedNode)
PnlSubFormDock1.Controls.Add(ctrlQ)
Code for delete button for which i need to raise event.
If MsgBox("Are you sure you wish to delete this customer ?", vbYesNo, "Delete Record") = vbYes Then
Deletecustomer(n)
End If
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Oct 6, 2011
i have to develop a software for motorola mc9090 that reads barcodes and rfids simultaneously, so i need to catch two different triggers: the one on the keyboard for barcodes and the other in the backside for rfids.the problem is that i didn't find any sample that illustrates how to set the trigger to read only barcodes, i found something on emdk 2.5 samples that shows how to set the trigger to read rfids but nothing for barcodes. So when i press any trigger the barcode reader is always enabled with rfids reader.Does exist a way to manage them with separated triggers?
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Apr 14, 2010
I asked on SO a few days ago what was the simplest quickest way to build a wrapper around a recently completed database. I took the advice and used sqlmetal to build linq classes around my database design.
Now I am having two problems. One, I don't know LINQ. And, two, I have been shocked to realize how hard it is to learn. I have a book on LINQ (Linq In Action by Manning) and it has helped some but at the end of the day it is going to take me a couple of weeks to get traction and I need to make some progress on my project today.
Click HERE To see my simple database schema. Click HERE to see the vb class that was generated for the schema.
My needs are simple. I have a console app. The main table is the SupplyModel table. Most of the other tables are child tables of the SupplyModel table.
I want to iterate through each of Supply Model records. I want to grab the data for a supply model and then DoStuff with the data. And I also need to iterate through the child records, for each supply model, for example the NumberedInventories and DoStuff with that as well.
For the record I have already written the following code...
Dim _dataContext As DataContext = New DataContext(ConnectionStrings("SupplyModelDB").ConnectionString)
Dim SMs As Table(Of Data.SupplyModels) = _dataContext.GetTable(Of Data.SupplyModels)()
Dim query = From sm In SMs Where sm.SupplyModelID = 1 Select sm
This code is working...I have a query object and I can use ObjectDumper to enumerate and dump the data...but I still can't figure it out...because ObjectDumper uses reflection and other language constructs I don't get. It DOES enumerate both the parent and child data just like I want (when level=2).
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Mar 12, 2009
Processing an XML file with LINQ to add records into a table in a SQL Server database via a data context. As we are adding records we need to assign the parents in various other tables. Most of the time we can find the existing parent and use it but sometimes we will need to create a new parent.Thought we could do this like this:
Dim defaultPub As publication
defaultPub = New publication With {.name = e..Value}
Dim pub = _Data.publications.Where(Function(s) s.name =
[code].....
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Jan 4, 2012
How can I use Linq to SQL in Vb.net to combine the records of two tables into a datagrid such as shown in this example:Assume i have two tables tbl1 and tbl2
tbl1:
col1 col2
A1 B1
A2 B2
tbl2:
[Code]...
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Apr 20, 2011
way to write the LINQ query. The parent class is simply a student's name and a list of test score data. The child class is a single test score datum. I want to find the worst (or best) score out of all of the TestScore values and then identify the student who had the best score.
Dim query = From s In studentList _
Where s.ScoreList.Select(Function(d) d.TestScore).Min _
= studentList.SelectMany(Function(g) g.ScoreList).Select(Function(h)
[Code].....
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Jun 1, 2012
Have seen some solutions for C# but do not know how to solve the issue in VB.NET.
Query:
Dim Query = (From t In myEntities.Bookings
Where(t.Ref = Someid)
Select t.People).Sum()
t.Ref field is an Int and so is t.People.
The SomeId value is the primary key of the related table. This issue is that there will not always be records in the Bookings table with a Ref value of Someid - so the query throws the following error.
I have seen others have got around this problem with catching the error, but from reading up on this and as per the error information it seems there should be a solution (in VB.NET) to cast the query or some of the fields in the query to nullable types?
Error is as follows:
The cast to value type 'Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type.
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Jan 25, 2012
I've got a table that caches calculated values for certain dates. I want to use LINQ to select all rows where the calculated value fields are null.But when I use isNothing I get an error that LINQ can't translate this into T-SQL. Is there a way to select null values with link, like this...?
Dim var = From rec As Record In myDataContext.Records Where IsNothing(rec.calculatedValue) Select rec
Other posts on stackoverflow mostly discuss how to avoid or check for null values with LINQ.
Note: I can't just set cacluatedValue's default to -1 to flag records whose calculated value has not been set (and then select those records) because I run queries that sum/average the calculated values. Selecting nulls seems cleaner and less bug-prone.
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Mar 17, 2010
Every LINQ example I have seen for VB.NET anonymous types claims I can do something like this:
[code]...
Now when I go to iterate through the collection(see example below), I get an error that says "Name "x" is not declared. For Each x in Infos It's like VB.NET doesn't understand that Infos is a collection of anonymous types created by LINQ and wants me to declare "x" as some type. (Wouldn't this defeat the purpose of an anonymous type?) I have added the references to System.Data.Linq and System.Data.DataSetExtensions to my project. Here is what I am importing with the class:
[code]...
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Oct 14, 2009
I'm using visual basic 2008 express edition by linq to sql for my database operation such as edit records. I did not use any sql server but I'm just using the built-in sql server within the visual basic 2008 express. I tried to revised the codes, no error in syntax but there's an error at runtime and it pops-up a window message saying its error message. What I want is to edit the records which were retrieved from the database into the text-boxes and when you click the button5 whatever the new value on the text-boxes should replace the previous one.The Account field is the field in my Table1 in memrec.dbml which I set up for primary key is true and the rest of the fields are false in its primary key.[code]...
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Oct 19, 2009
Is it possible to do a multiple records editing by linqtosql method in one click event? What I've been trying to do is to edit all the names in the table which are having the same account number. I was able to edit but only one name has been edited and the rest are not.
The codes I used.
Private Sub Button2_Click(------------) Handles Button2.Click
Dim accnt As String
accnt = Textbox1.Text
Dim db As New memrecDataContext()
Dim editrecord = From mem In db.Table1s
[Code] ......
Why is it these codes could only edit records in one datarow?
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Oct 14, 2009
I'm using visual basic 2008 express edition by linq to sql for my database operation such as edit records. I did not use any sql server but I'm just using the built-in sql server within the visual basic 2008 express. I tried to revised the codes, no error in syntax but there's an error at runtime and it pops-up a window message saying its error message. What I want is to edit the records which were retrieved from the database into the text-boxes and when you click the button5 whatever the new value on the text-boxes should replace the previous one.The Account field is the field in my Table1 in memrec.dbml which I set up for primary key is true and the rest of the fields are false in its primary key.The code below still found an error when you run the program and it pops-up a window which says:
NotSupportedException was unhandled - Sql server does not handle comparison of NText, Text, Xml, or Image data types.It highlights a yellow background on the line:
db.SubmitChanges()
These are what I see on each field's property on Table1 in memrec.dbml property window:
Access - Public
Type - String(System.String)
Server Data Type - Text[code]........
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Sep 26, 2009
This is the hardest part of LinqtoSql database handling operations in visual basic 2008 I ever encountered,w/c is the update operation cause Ive been posting this thread several times from the other forum site but noone yet was able to answer my question,examples were given but its not efficient cause it won't specify based on the codes i gave and i know its not easy but im still hoping that one of the answerers of this forum will be able to resolve this particular linqtosql operation codes. I used textboxes in manipulating all data into the database such as displaying records, adding records, & updating records, basically I used with textboxes in doing those database operations. I will give you 3 block of codes w/c corresponds those database operations I used and differentiate from each other inorder for us to determine why one of them has no progress or won't do its operation w/c is the update operation...
*************Block of Codes#1(Adding Records)*************
Private Sub Button1_Click(------------------) Handles Button1.Click
Dim db As New memrecDataContext()
[code]....
I would like you to identify,differentiate, or troubleshoot the block of codes#3, or anyhow, why it has no progress at all or it won't edit and change the records but it runs and no error in regards with its code, and the other 2 blocks of codes were able to successfully do its operations.I was just wandering why only the block of codes#3 is not doing its operation successfully when you change the record being displayed in the textbox.Is there a possible way to edit records in the textboxes?If there is.... Is it possible to debug the block of codes#3 to successsfully do its operation? If you could possibly give an example,can you based it on the block of codes#3?
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May 22, 2011
Basically i have a list(of TransRecord)
vb Public Class TransRecord
Public TableName As String
Public PKs As String
[CODE]...
And want to create a linq filter to select only unique records for TableName + PKs (group by) ... but want it to select only the record with the highest ID for this group by.
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Feb 2, 2011
I'd like to take all suggestion either in C# or VB.NET.I have a DB diagram like the image below. I also include the database script here [URL]In the Students table, CountryId and RoomId column are allowed null. Because some records do not have info about room and country yet.Also, some students do not have essays.I'm doing a joint query with all tables. I want to select all students to project the result like this:Wanted query result.
Here's my current query that gives the result like the image below:
Dim db As New DBDataContext
Dim query = From st In db.Students _
Join c In db.Countries On c.Id Equals st.Id _
Join r In db.Rooms On r.Id Equals st.RoomId _
[code].....
current query result I got only one result back because I have (2) William NoMan record in every table. But I don't get anything about others, like (3) Sync Master who has everything but RoomId.What do I need to modify the query above so it will give me all students like in the wanted query image above?
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Nov 11, 2011
In code ConfigurationManager.AppSettings("IsFill") showing null
but when i open exe.config file manually that key is present in file
den i modify exe.config file using below code
Dim configFile As Configuration
configFile = ConfigurationManager.OpenExeConfiguration(Application.ExecutablePath)
configFile.AppSettings.Settings("AppVersion").Value = "1.0.1"
configFile.Save()
[Code]...
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Apr 25, 2012
I am new to this forum. I have created a module in which declared one structured in public. There were some fields earlier in the structure.
[Code]...
I have included statement includes project.modulename in my main project form where i am referring this structure. everything worked fine. Today, i added new field to the structure by name "example as string" and written some code in module itself to access this field. even this is working fine. but when i am trying to access this field in the main code it is not showing example as structure field and saying not a member.
The drop down suggestion of IDE is not showing this field in main code but in module code it is showing the field. Later, i also found that my debugger is also not working. I tried to clean solution, restart IDE, computer but nothing seems to be working.
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Mar 21, 2012
I have users check off lab facilities in a UI. I want to use linq to fetch corresponding records for all of the labs that they have checked off. Basically,
Dim myRecs = (From l As EpiData In myDataContext.EPIDatas Where l.facility= _
one of the checked labs
So basically, I need to write a linq query where the "strings" to match are determined at runtime. Is there any way to do this easily? I know that there is a library out there called dynamic LINQ, but (1) it's in C# and I'm writing in VB (2) I'm really just looking for a single, simple solution for this single case.
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Apr 19, 2010
I have created a class called Student, with five private variables: [code] My main form is divided into a number of different sub procedures. In one of them, I used a streamreader to take the first name, last name, and phone numbers of a list of records in a text file called PersonalInfo.txt. It seems to work just fine. [code] I have another, separate sub procedure in which I read a different text file containing the "averages" for the students. The first average from Averages.txt belongs with the first student in PersonalInfo.txt. The second average goes with the second student.. How do I add the student average information to the properties of the student records created in the previous sub procedure? [code] I realize why this wouldn't work, but I can't figure out how I could use my counter to reference a specific student.
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Feb 8, 2011
this is somewhat related to my previous issue which was solved: [URL] Now my problem is none of the affected controls are changing on the form. The form itself is not frozen as an elapsed time is going fine on it. when I "F8" thru the code the I see the controls contain the correct values and if I do a messagebox display of the control contents it displays the correct value. but the controls themselves do not change on the form. for example: label1.text will still show blank even though thru code it contains "test". what am I missing here?
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Aug 11, 2011
In datagridview,i want to display the amount without decimals. so whatever values coming from backend,i'm directly assigning to cells value.then in cell formatting event, i'm formatting values without decimals,so here after formatting,the formatted Cell Value not reflecting in Original value. when i read the formatted value , its displaying only assigned value not formatted value..ex :
Public Class Form1
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
DataGridView1.Item(0, 0).Value = Val(12.123)[code].......
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Mar 23, 2012
Basically the question is, Why are NONE of the changes I've been making in the designer reflecting on the program when it runs ?'none' is in bold because I've tried moving everything around and nothing seems to be affecting it, it's like it's reading from a different design file, I tried reloading the project and that did nothing, and none of my code affects position of any items on the form (way too much to post it all)
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Nov 14, 2010
I am using a class to track if a user cleared their personal information found within some text boxes on a form. In the button click event to clear the text boxes I am creating a new object to the class and assigning true to one property value. Sounds simple until I try and submit the form with a different button, and create a another object reference that I use in an IF statement to check the property value for true. Every time the statement fails because the value being returned from the getter in my class is false.
[Code]...
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Jul 13, 2009
I am developing an application on VB2008 with MySql as database. I opened the connection without any errors. I have three fields/columns in my database and on the form. When I am running vb form data is not reflecting on to form fields.
I have written the following code in form load event.
'Dim cn As ADODB.Connection
'Dim rs As New ADODB.Recordset
'cn = New ADODB.Connection
'cn.ConnectionString = "DRIVER={MySQL ODBC 3.51 Driver};" + "SERVER=localhost;" + "DATABASE=in_out;" + "UID=root;" + "PASSWORD=pacvision;" + "OPTION=3;"
'cn.Open()
'MessageBox.Show("Connection Opened Successfully")
'rs.Open("Select * from deptno", cn.ConnectionString, ADODB.CursorTypeEnum.adOpenKeyset, ADODB.LockTypeEnum.adLockOptimistic)
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Apr 16, 2009
I have 3 text boxes that are related on a form. They come from the same dataset and the same table in the dataset. The 3rd textbox is defined in the table as the product of textbox (really the column) 1 and 2. The problem is when I save after changing textbox 1 or 2, 3 does not update reflecting the new product. I have a different form using a different dataset that does a similar setup correctly. What could be the difference between the 2 forms or tables or dataset that I could look for?
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Oct 4, 2010
Basically for a while now if i wanted to set a chks setting i would do this..
[Code]...
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Jul 23, 2008
the access data are not getting reflected on the DataGridView unless the form is reloaded again. I am acessing the MSAcess data for back end processing (SELECT,DELETE)using odbc connection and displayin on .NET form using DataGridVew
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Jul 26, 2011
I have an editor created invb.net that creates html files. And when i click the button run , the Internet Explorer opens my file that is inside the Richtextbox.
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