Understand ComboBox And The Use Of Columns (or Equivalent) In .NET For Instance?
Apr 28, 2011
I'm trying to understand ComboBox and the use of columns (or equivalent) in .NET For instance, I have a bound form with a combo box and a table that i want to feed it. In the table I have EmployeeID, LastName, FirstName. I want the "Bound Column" to be the EmployeeID, but the combo box to display the last and first name of the employee. This was very easily obtainable in VBA but is giving me some grief in VB.NET. I've played around with the datamember and valuemember properties of the combobox but have not had any luck.
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Apr 23, 2009
I'm trying to understand ComboBox and the use of columns (or equivalent) in .NET For instance, I have a bound form with a combo box and a table that i want to feed it. In the table I have EmployeeID, LastName, FirstName. I want the "Bound Column" to be the EmployeeID, but the combo box to display the last and first name of the employee. This was very easily obtainable in VBA but is giving me some grief in VB.NET. I've played around with the datamember and valuemember properties of the combobox but have not had any luck.
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Apr 15, 2009
Hi, I'm just beginning to teach myself how to do OOP in VB 2008 Express. I have a quick question after seeing a video online.Is a VB variable the equivalent of an 'instance' in Flash and a VB object like a 'symbol' in Flash? Is this what it means by a variable being a reference or pointer to an object and not the object itself?
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Sep 6, 2006
I'm filling a combobox from a dataset that has three columns, DealerID, DealerName, DealerState. I can only get one column to display. show two or more columns in a combobox? My code follows:
adapter.Fill(datList, "tblDealerID"))
Dim drDealer as DataRow
For Each drDealer in datList.Tables("tblDealerID").Rows
cboDealer.Items.Add(drDealer("DealerID"))
Next
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Jan 29, 2010
Does anyone know how I can go about concatenating multiple columns from a table to populate into a combobox? I have 4 columns from which I need the data to show up in 1 line when clicking on the dropdown/combobox list. I'm not sure if I have to deal with the display member or the value member.
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Apr 2, 2010
i just finally got my code, with the help of you guys, working to fetch column values from my database and display it in a ComboBox.
Now i am thinking to myself that simply displaying a customer's surname just is not enough due to repetitive issues etc. What i propose that i should do is have multiple column values in a the combo box. For example
CustomerID, Surname, Firstname
My current code is:
con = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:My DropboxDocumentsTaxi Service ProjectDatabaseTaxiProjectDatabase.accdb;")
con.Open()
[code]....
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May 11, 2009
I have this code here:
[Code]...
I know there is MyDataTable.columns How can I get it to put the columns into a ComboBox so i can select them?
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Nov 9, 2010
So i have a datagridview with two combos, when the form it's created i fill the first one with all the MainValues, and the second one with all possible values for the MainValues (called SecondValues) (1..N).Now my issue, when the user selects one value from the first combo i want to fill the second combo with all values related to the selected MainValue, i can do this for example by filling the datatable again with a parameter that filters the data, but if the previous rows have different main values, the dgv throws errors because it doesn't find the binded ones in the new filtered datatable.
How can i handle this? One datatable for each line?! Other thing, i'm using the SelectionChangeCommited event for handling the values change (in theEditingControlShowing), but if the user uses the keyboard to select the values the event doesn't behave in the same way or the way that i need. The values in the combo are numeric values (1001,1020,2010,3010), when the user select one of the values, i need to fill another cell in the same row with the number selected plus some string, example combo:1001 cell:1001XPTO. So if the user presses 1 in the keyboard the combobox selects the 1001 and fills the cell with 1001XPTO, but if i keep pressing the keyboard to select the 1020, by pressing 0 and 2, i get the 1020 selected in the combo, but the cell remains with the 1001XPTO.
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Jan 16, 2012
I am using the following code which populates a combobox with Location Codes from a table called tb_StoreLocations.
Dim SQLStr As String
Dim dtTableData As New DataTable
Dim dbDataAdapter As SqlDataAdapter
[code].....
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Nov 8, 2010
I have seen something like the following in many software. Combo box populated and displayed with multiple columns (for example stock code, stock description). But now I am only able to populate with stock code. May I know how to achieve this? I know it can be done by calling a form (And I can do whatever coding in this form) out when clicking on the combo box. But I am looking for better solution, or is it possible to populate the whole datagrid into the combo box as source instead of only the data.
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Dec 13, 2010
I have a datagridview that has 1 combobox column (it will eventually have between 1 and 3 more) but I can't find anything anywhere on how to add rows to this column. I create the columns:
[Code]...
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Dec 14, 2010
I am working with an Unbound DataGridView. I would like to vary the contents of a second combobox based on what is selected in the first. I have code to add the columns and populate the first combobox, but I can't figure out how to do the second one since it can (and usually will) have a different list for each row AND the list must change when the selection in the first is changed.
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Jul 6, 2010
I have a combobox that is connected to a datatable with 3 columns. When i click a button i want 3 values from the selected item to be transferred to another datatable.The easiest way without any hassle to do this is via the Combobox.Text, Combobox.SelectedValue and....eyy nowhat?
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Oct 26, 2011
The user picks x amount of scenarios from the combobox, and x amount of columns appear in the datagridview. If the user changes the number of columns from x amount to y amount, the columns should be added/removed respectively but currently when y amount is chosen x amount of columns are in the datagridview.
I'm not sure how to do this, I've tried using an IF statement under the .SelectedIndexChanged event but the code adds columns until it reaches as high as it can go, then pulls an error saying too many columns.
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May 19, 2010
I'm trying to concatenate nonnull multiple columns from a database into the text property of a combobox. Right now, I'm receiving an "IndexOutOfRangeException was unhandled name, address1, address2". The line, "cboFreight.Text = drFreight("name" & ", " & "address1" & ", " & "address2")" is where the error is occurring. Here is my code for this section:
Dim drFreight As SqlDataReader = cmdCorrespFreight.ExecuteReader
While drFreight.Read()
'If "address3" <> "" Then
If IsDBNull(drFreight("address3")) Then
[code]....
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May 19, 2010
I'm trying to concatenate nonnull multiple columns from a database into the text property of a combobox. Right now, I'm receiving an "IndexOutOfRangeException was unhandled name, address1, address2". The line in red is where the error is occurring. Here is my code for this section:[code].....
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Oct 18, 2010
I have been given an old dll and the assignment of accessing it through C# .NET 3.5. I believe the dll was originally built with VB6, but am not positive. There is no documentation or source for the dll aside from an example for how to use the it in VB6. I have been able to succesfully access it through VB.NET 3.5. Example code for accessing looks like this:
myLib = CreateObject("MyLib.api")
myConnection = myLib.CreateObject("NameOfConnectionObject")
myConnection.do_something("abc")
There are several different objects that are created from the library and all of those objects have different methods. I tried using different dll reading tools, but all the export methods show up as garbage. I also tried importing the dll in visual studio, but I get an error stating the dll is not accessible and/or not a COM object or assembly. So, I only know about the methods from the old documentation which is sparse. how to access in C# and/or find out more about this mystery dll?
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Apr 24, 2012
i cant understand what constants are.
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Dec 4, 2011
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim d As Integer
Dim price(20) As Double ' Adjusted close price
[code]....
What is the for ... next loops in the second subroutine doing? What is the sim() array meaning?
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Feb 1, 2009
I have a modem that I've been trying to communicate with only to discover this....went to the modem properties and queried the modem.....
AT+FCLASS = 0,1,8
AT#CLASS = ? COMMAND NOT SUPPORTED
(And I had been trying to use AT#CLASS = 8 all day).So, what does this mean?That the modem is automatically in voice mode (or will automatically choose it's own mode) and forcing it isn't necessary?Still no luck with the connection response messages either -- RING, etc.All I can do is make a call and the called number will appear in a textbox.
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Feb 18, 2011
I am getting a build error. If I try to build again after getting this error, it will build just fine.
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Jan 4, 2011
[code] I cannot seem to understand why left & lan isn't working in the vb 2008 edition
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Jun 6, 2011
how to understand a msakeditbox in null?
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Jun 5, 2010
I've been trying to understand classes and objects. Yes, I'm thick headed and slow, but I made the decision to go to .Net and I am determined to improve my coding skills to be more efficient. I have spoken to Atma several times on the topic and read most of his posts concerning classes and objects, but still came away a little baffled (He's really advanced for me yet). I needed a simplistic analogy for a reference point to begin understanding. I was reading about OOP written by MikeJ in the following thread/post ...[URL] and it all started to become clear in this statement , but I would like some reassurance that I'm getting it ..."A car IS-A vehicle, while a dog HAS-A tail. The car would be an object declared as type Vehicle, while the dog would have a member that IS-A tail. However, Fido IS-A dog. The dog class is the base template for all dog objects, so when we declare Fido as a dog, Fido is an object. Since Fido IS-A dog, Fido HAS-A tail."
From this I have taken the following understanding...
Vehicle ... ' Class
Car ....... ' Object
Truck ... ' Object
Van ....... ' Object
And from that can I infer that this is true?
Dog ....... ' Class
Fido ... ' Object
Tail .. ' Member of Fido
So to apply this to a program I wrote recently that tracks Generator service...
Generator ' Would be the class
Brand X ' Would be an object
Spark Plug ' Would be a member
Gas Tank ' Would be a member
Brand Y ' Would be an object
Brand Z ' Would be an object
This statement also helped ...
""Class" and "object" are sometimes used interchangeably. However, classes describe the structure of objects, while objects are instances of classes. Each instance is an exact copy of its base class. Because an object is an "instance" of a class, the act of creating an object is called instantiation. To describe it better, a class is a blueprint, and an object is a building based on that blueprint". I can understand this (I think) and it refers to a basic template such as ..."Generator" (my class or blueprint or template) Generators have an engine, powerplant, fuel tank, etc. These are basic requirements to be a generator. (Template or Blueprint) They can differ by Brand of engine, Size of powerplant, and type of fuel used. (Based on template or blueprint) Do I have it down now? MikeJ also made this statement ..."you can't access certain types of class members from outside of the class itself." From this I assume you would need to assign a Global variable the value of the class member if you needed to use it outside of the class?
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Nov 21, 2009
I'm just getting back into VB and was never a pro. The last environment I was in, briefly, was VB6 but spent a good amount of time coding in early VB's back to QB.I'm trying to read RSS feeds and found a nice demo reader but now I want to understand the code I'm seeing:[code]
1. Why does the demo create a new XML to read through an existing XML or is this all in memory as I can't find an actually file? Is this even needed as what I want to do is read the RSS feed, grab some info from it (Source, Title of each story, Date stamp, author and the story text) and then process that in various ways (not actually view it... I want to e-mail specific stories directly to me that fit my search criteria). Or is this just opening the XML out on the web? That would explain why sending it "test" gives me an error saying it can't find "test" in the bin folder as without an HTTP address it goes local.
2. doc.load... what check can I perform here to be certain that the data entered by the user is actually a valid feed? It should, for example, have a first line header that is reliable but is that the best method?
3. Where or how are the elements stored that I can then refer back to pull the data out I want?
4. I don't understand how this part works: navigator.Select("/rss/channel/item/title") Can someone shed some lite on the 4 pieces at the end?
5. I'm assuming the clean-up isn't really needed for e-mail but I didn't remove it as it doesn't seem to harm anything.
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Feb 20, 2011
I have Visual Basic 2010 and also bought a book to study and practice problems. I know how to add controls and assign properties but get confused with the coding part.understand this somewhat?
Here is one problem I am working on-
Write a program to make change for an amount of money from 0-99 cents input by the user. the output of the program should show the number of coins from each denomination used to make change.
Now I know what controls i need on the windows form but I am sorta lost on the coding to make this program work.
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May 25, 2010
At the following cmd.ExecuteNonQuery() line, I get the following error message: [code] I have followed the example at page [code] as closely as possible, but it does not work.Additionally, I am not sure of the syntax for the length (64) that I have for the BigInt or if it should even have a length.All of the examples that I have found in MSDN uses only parameters with character rather than numberic type. [code]
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Aug 5, 2011
"write sub prototype for a procedure whcih is named my data and has first parameter as a string which can be changed and second parameter of an integer which cannot be change"
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Aug 6, 2011
Are you familiar with prefix and postfix? I just wonder how to solve it especially if the expression is too long.
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Aug 1, 2010
I want to make an application that will remind me to give a break once in 45-50 minutes. But I want it to determine if I am playing a game or not at the time that I have to give break. In short, if any application is in fullscreen mode (or maybe using graphic card) I want to know. Is there anything about that in .NET?
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