OOP - Declare Two Datatables And Fill Them Both From A Datatable Returned By A Function In Class
Sep 27, 2010
When I declare two datatables and fill them both from a datatable returned by a function in class, that when i filter the one it seems to filter the other aswell?
For example:
I declare the datatable and initiate my class:
Dim DatatableOne As New Datatable
Dim DatatableTwo As New Datatable
Dim MyClass As New MyClass
I then call the function that returns a datatable and apply it to datatable1 and 2 Then fill two DataGrids with the table:
DatatableOne = MyClass.GetTable()
DatatableTwo = MyClass.GetTable()
DatatableOne.DefaultView.RowFilter = "Name = 'Tom'"
[CODE]...
For some reason i don't understand but both grids end up with the filtered data?
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Jan 25, 2010
I have the following statement, I want to turn it into a Public Shared Function :
If isEmployee Then
Dim employeeInstance As New Employee
employeeInstance = GetEmployeeInstanceByUserId(userId)
[Code]....
Public Shared Function GetWorkerInstance(Byval isEmployee as Boolean) As ...(not sure what to write here)...
There two possible return Type. I'm not sure what I should declare for the function return type.
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Jun 1, 2012
I'm having a hard time joining 2 datatables and have the joined datatable as result. First datatable (labels) holds data including a printerid. Second datatable (printers) holds printer references (id > unc). I would like to have as endresult (joined) a datatable with all data from the first datatable with the field (unc) of the second datatable. [Code]
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May 14, 2009
I'm following this tutorial: [URL]..except I'm connecting to my own data source - a MS Access database.This is the query I have setup with the dataset:
SELECT Terminal_ID, SUM(Transaction_Quantity) AS Total
FROM tblTransaction
WHERE TransactionType_ID=3 and Transaction_DateTime>[@fromdate]
GROUP BY Terminal_ID
The debug fails immediately because it needs the extra parameter so I change the code from:
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'tetrisDataSet.tblTransaction' table. You can move, or remove it, as needed.
Me.tblTransactionTableAdapter.Fill(Me.tetrisDataSet.tblTransaction)
[code].....
The error I get on build is:Too many arguments to 'Public Overridable Overloads Function Fill(dataTable As tetrisDataSet.tblTransactionDataTable) As Integer
...I gave it the extra parameter, so what gives? Something special I need to do as it's a datetime field?
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Apr 21, 2009
I'm trying to access the Count Property on the array of rows returned by the datatables select method, this is after converting the Web Project to 3.5
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Jan 30, 2010
I want to use a background worker to reduce a form's loading time. I have already created this and reduced the loading time. But this time, something didn't work right:
Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.Cursor = Cursors.WaitCursor
BackgroundWorkerMain.RunWorkerAsync()
End Sub
[Code]...
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Oct 6, 2009
Datatable object within class function + garbage collection?
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Apr 6, 2012
I am using Microsoft Access database. Since Access Database Table cannot have more than 255 columns, I am using vertical database partition technique where I have splitted informations into 5 different tables. Each table has 100 columns, and first column is primary key. Now I need to read data from these five tables so that I can export it into Excel file.
[Code]...
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May 27, 2010
I have two datatables, which come from different sources. One is Sales, the other is Products. What I'd like to do is create a filtered version of Sales, in that in that it contains Sales which have a matching ProductID in Products.
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Dec 12, 2011
I have a datatable that contains 8 columns. To make this more presentable I have managed to pivot three of these columns. That will not do since I then loose 5 columns of information. To overcome this problem, I thought of just joining the two tables in vb.net.This seems more difficult than expected. LINQ are hard to learn compared to SQL. I have tried to pivot the query in SQL but am not able to.Here are the query:
"SELECT t1.Journal,t2.Kunde,t2.Kundenr,t2.Lokalitet,t2.Lokalitetnr,t2.Analyse,t2.Positive,t2.Totalt " & _
[code].....
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Aug 6, 2010
I am trying to add NewRow to the database by using datatable in dataset, but before I do that I want to make sure that row is not already there. I create new row for the datatable I am working with, fill it with information. I fill datatable with the row from database that has the same primary key as my NewRow by using tableadapter.fill method, but when I do that my NewRow that was never added to the datatable is filled with information from database(and not information that I assigned to it). I count rows in my datatable before I fill it and it's 0, so why is my NewRow affected by Fill command? (I am using VB.NET 2005 Framework 2.0)
[Code]....
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Mar 29, 2010
I created a DataSet using the DataSources wizard. I can display the rows of each Datatable one at a time. But in this case, I needed to add a new DataTable (newDT) using the Add New Table Adapter control(?) on the toolbox. newTable is derived by JOINing three different existing tables (or, dataTable) in my DataSet designer. The query works fine and returns all the data as expected. Trouble, if I try to display the rows of the newDT on textboxes, I get a NULLREFERENCE Exception.
[Code]...
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May 8, 2012
Create a class named Service. Inside the Service class, declare a class variable named Started. The datatype of this variable is Boolean.Public Class Service Dim started as Boolean End Class Create a class named Server. Inside the Server class, declare a dynamic array that can contain elements of the type Service.(Note: For convenience, both the array and the variable Started can be accessible from a client program that creates an instance of Server and Service respectively)
Create a constructor for the Service class. When the constructor is executed, it will set the value of the class variable Started to True. Create two new classes: WebServer and DatabaseEngine. Both of these classes inherit from the class Service. Inside the Service class, declare a Sub procedure (method) named Terminate. This method should display the following text Service stopping in a message box when executed.This method can be overridden in classes that inherit from Service class.
Inside both the WebServer and DatabaseEngine class, override the method Terminate inherited from their base class Service. Both methods should first call the base class Terminate method. The messages Web server stopping and Database engine stopping should also be displayed in a message box when the Terminate method for the WebServer and DatabaseEngine are called respectively. These messages should only be displayed if the Started variable inherited from their base class is not equal to False.
Inside the Server class, declare a method named Shutdown. This method does not return any value. When executed, it will call the Terminate method for each of the Service instances (if any) in the arrServices
array. You should call the Terminate method within a For Each loop that loops through the elements of the arrServices array.
In the Sub Main method, create an instance of the class Server. Set the size of the arrServices array in
your Server instance to contain 2 elements. Create first a WebServer instance and then a DatabaseEngine
instance into this array. Call the Shutdown method from your Server instance.
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Jun 23, 2009
I am currently writing unit tests for an application near completion (before management looks at it and turns it inside out). I am testing the business layer and a method is set to return a datatable of all "GroupID"s, which are simply an integer to represent the group that a user belongs to.
I'm assuming the best way to assert on this unit test would be to assert that the correct groupIDs are being returned from a controlled test database. However, I'm not sure how to assert on a datatable. Is the only (and best) possible way to accomplish this to simply loop through the datatable until it's empty and add each value to an array of integers? How would one go about asserting on this test?
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Feb 6, 2011
When I query a DataTable using LINQ, are the rows returned as references? Either way, is it possible to control this behaviour, so that rows are either returned as references or as new rows?My guess is that all objects are returned as references by default, since that seems to be the normal behaviour in most programming languages.
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May 6, 2010
If you run this code you will see that the 500 PictureBoxes that are added ( this is easier to show than adding pixels as a pixel is only a single point ) fall mainly on the diagonal.With regard the RANDOM class, why should this be like this when the bounds of the instances are? >>
p.Location = New Point(x.Next(0, Me.Width + 1
), y.Next(0, Me.Height + 1 ))
as in this code.>>
[code].....-2138214fdeb4
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Mar 29, 2010
I need to create an HTML email that consists of four tables. My idea is to create four different datareader or datatables and pass them to a class that converts them to HTML. Please help me get started.I've done this before by creating a stringbuilder then appending text to it and then sending it as an html email. but, now I want to build a class so I don't have to do it the long way all the time?
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Apr 4, 2012
How to give another function's returned value in LINQ.[code]but in above query I should write code to store the return value of GetObjProperty Value(p) and add obj-p and returnValue combination to the dictionary.The last line below code is wrong. but please suggest me how to correct it. My intention is, I want output collection(say dictionary) of each fruitname and its color(returned by other function call) for all the fruits which the GetFruitColor is not nothing(it can be empty or valid string).[code]In above code last line is wrong. So how to put getFruitColor in k, how to correct it to save the k value and give me output as dictionary of fruit and k value.
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Sep 5, 2010
Why this code doesn't work? It returns an unexpected value actually total = 0.
total = Cscore(TextBox1.Text) * CDbl(TextBox2.Text)
When trying this
total = TextBox1.Text * TextBox2.Text
It returns the expected value but I need to pass textbox1.text to the function to get the desirable value
The function is this
Public Function Cscore(ByVal score As Integer) As Double
Select Case score
Case score = 100
Return 5.0
Case score >= 95
[Code] .....
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Apr 2, 2011
I have many functions that perform mathematical calculations.
Here is one for example:
Public Function internaldiamofcasingpipecalculation(ByVal Externaldiameterofcarrierpipe As Double, ByVal insulationthickness As Double) As Double
[Code]....
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Nov 17, 2008
how to declare an internal class within a public class using vb.net?
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Feb 22, 2010
I'm new to VB.NET and want to parameterise the SQL Connection Strings in my VB.NET App. I've added a function to my Main Form to retrieve the App.config File like:
Imports System.Configuration
Imports System.Configuration.ConfigurationSettings
Public Class MainMenu [code]....
In my other forms when i want to reference the Connection String, i get an error saying getConnStr is not declared?
Private Sub UpdDept_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Try
myconnection = New SqlConnection(getConnStr()) <=============
Dim mycommand As New SqlCommand()
why i get this when i've declared the Function as Public?
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Mar 18, 2009
When the AlertsSettings.xml is not present the Appsettings is assigned to nothing. The variables that follow that definition rely on the existance of that information which will normally be set by the load method. But when there is a problem and either of the variables do not get a value how do I handle that in the code that relies on those values. The Settings class deserializes an xml document and assigned values to properties.
Sub Main()
Dim Appsettings As Settings = Settings.Load("AlertsSettings.xml")
Dim AlertsServer As String
[Code].....
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Aug 5, 2011
This should be a fairly common question, but I haven't found a straightforward answer anywhere.
If I instantiate an object within a function in VB.NET and return it, does it return it be reference or by value. IE - should I be worried about performance if I write something like this:
Public Function ret_obj_func() As big_object
Dim ret_obj As New big_obj(<lots of stuff>)
Return ret_obj
End Function
If I call this function from somewhere else, will it instantiate the object in the ret_obj and then create a deep copy to pass back a copy to the caller, Or will it just pass back a reference?
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May 2, 2012
I'm trying to establish a connection to my SqlDatabase while getting the connection string from a function. This will eventually lead to dealing with the appconfig file, but for now I'm just getting the basics established.
Imports System.Data.SqlClient
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[code]....
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Jul 2, 2009
Combobox with bound rowsource, but I want to change the displaymember to a string returned by a procedure. In Access/VBA I would have a little function to build the string, then simply code the recordsource of the cbo as:
"SELECT ClientIDS, fnGetName([ClientIDS]) AS ClientName FROM tblPerson ORDER BY fnGetName([ClientIDS])".
Pretty straightforward, but I've messed around with this for hours in VS2005/VB to no avail.SELECT ClientIDS, fnGetName
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Feb 25, 2009
I have a 2 dimensional array of groupboxes that I use to populate a form setup so the first indice is a tab number and the second is the groupbox number.The user can dynamically add tabs to the tabcontrol but I need to add and populate groupboxes to the new tabpage and I can use existing groupbox data in the array for default values.I understand I have to code a deep clone of the source groupbox as it has textboxes in it so I want to add a cloneGBox function that returns a new, populated groupbox when I pass in the x,y indices for the source groupbox in my array.
dim gbx as groupbox = cloneGBox(x,y)
and code cloneGBX as
public function cloneGBox (byval x as integer, byval y as integer) as groupbox
[code].....
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Jun 22, 2011
I have a DataTable "dt1" that has thousands of rows.
Columns are:
- Type_And_Model
- Val_1
- Val_2
- Val_3
- Val_4
There are only about 30 different "Type_And_Model"-types.How can I insert into a new DataTable (dt2) only distinct "Type_And_ Model" types with the sum of their specific values and total appearance number?
dt1 - DataTable with thousands of rows
Type1 2 2 5 5
Type1 4 2 7 5
Type2 2 2 5 8
Type1 2 2 9 5
Type3 3 2 5 5
Type1 6 2 5 7
Type3 2 7 5 9
Type1 8 2 9 5
.....
INTO =>
dt2 -DataTable with disinct types and their sum values + appearance numbers.
Type1 22 10 35 27 5
Type2 2 2 5 8 1
Type3 5 9 10 14 2
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Jul 16, 2009
I am calling an Oracle function PKGDummy.F_EMPDATA using vb.net.
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Jul 27, 2010
I have the code below. The code returns a string in (IntersectingPoints) for X and Y. I need X and Y values to be in single and stored in an array to deal with later.[code]...
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