VS 2008 Randomly Select DataTable Row And Get Data?
Dec 19, 2009
The next step is I need to build a randomizer to randomly select a row and read the columns of that row into varibles.I have a working randomizer that can randomly pick a number between min and max values but what I don't know if how to select a row / How to find out how many rows are available and how to read the values into varibles.Am I right in declaring an Integer Varible then using:
AvailableRows = DDT.Rows.Count
Then use my Random Function to pick a number between 0 and AvailableRows
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May 17, 2010
How do I randomly select 1 string from some Text? For example: Main text:
[Code]....
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Feb 23, 2012
I am little bit stuck here .. I have a datatable as _
Dim dtPupil As New DataTable
dtPupil.Columns.Add("PupilId", GetType(Integer))
dtPupil.Columns.Add("Forename", GetType(String))
dtPupil.Columns.Add("Surname", GetType(String))
I made a select (assuming names combination will be unique)
Dim strQuery As String = "Forename ='" & forename & "' and Surname = '" & surname & "'"
Dim dr As DataRow()
dr = dTablePupil.Select(strQuery)
I wanna have PupilId as an Integer of the row that match, so
Dim PupilID As Integer = ??????????
What do I need to write here ? There will only be 1 row returned.
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Sep 28, 2009
I have a search function on my company's website (based on .NET 2.0) that allows you to narrow the product catalog using up to 9 different fields. Right now, after you make your selections on the frontend I am building a dynamic query and hitting the database (SQL Server) to get the resulting list of items numbers. I would like to move away from hitting the database everytime and do all of this in memory for faster results. Basically a 3500 - 4500 row "table" with 10 columns: the item number (which could be a primary key) and the 9 attribute fields (which have repeating values for many many rows).
There can be any number of different searches between the 9 columns to get the items you want:
Column A = 'foo' AND Column D = 'bar'
Column B = 'foo' AND Column C = 'bar' AND Column I = 'me'
Column H = 'foo'
etc...
Based on my research, the .Select() function seems like the slowest way to perform the search, but it stands out to me as being the quickest and easiest way to perform the narrowing searches to get the list of item numbers:
MyDataSet.Select("Column B = 'foo' AND Column E = 'bar' AND Column I = 'me'")
In my specific case, what method I use as an alternative that has the same narrowing functionality and better performance instead of settling for the datatable.select() method?
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Apr 8, 2009
I was trying to write the following select stmt but i am getting an error that the parsename is not identified.
[Code]...
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Jun 9, 2011
I am interested in making a program to randomly populate gym-exercises from a group of them that I will populate. For instance, I want to be able to check "triceps," and then have "triceps kickback" pop up from a larger group of exercises, and the next time I click it another triceps exercise will pop up.
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Nov 19, 2009
How would I randomly select an item from a combobox
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Dec 30, 2009
I just discovered the DataTable.Select-function, and boy I'm glad I found it! It makes my code run several times faster. But, I don't quite understand why it's so much faster than my previous code. In my first code, I looped trough my DataTable to find the specific row, like this:
[Code]...
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Jun 15, 2010
I have a class and I am trying to randomly select 3 items to display on a page (each item should be unique so that there is no repeating).I have some code that works(ish). The problem is that when I track the random numbers it takes about at least 50 attempts for the application to select a different random number than the one that was chosen the first time (defying the laws of probability).[code]
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Aug 2, 2011
I have a button called 'populate'. I need it to randomly select items in combobox1 when I click it. Here is what I have tried doing but it doesn't give me the desired results.
Dim sacostofsyscheckout As Integer
Randomize()
sacostofsyscheckout = CInt(CInt((1500000 * Rnd()) + 3000000))
[Code]......
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Apr 26, 2010
Right so I have made a graphic of a coin being flipped. Heads is shown on one graphic, tails on the other. I wanna set it up so that when I hit go it will randomly play one of the two graphics on one of my forms.How easy is it to add a .gif file to a form that can play when told to? What is the code im looking for to help with me with what I'm trying to do?
Another thing I plan to achieve is also a random number generator that will display a number on a ball that rolls on to the screen. So the displaying of a number will be timed to show up when the ball comes in focus. I have some code that I have used previously to generate a number, but I wanna get the generated number to show in time with the ball rolling up.What are some wait commands to use in vb .net? This is the code I am using to randomly generate a number.
vb
Dim r As New Random
TextBox1.Text = r.Next(0, 150)
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Aug 28, 2011
I'm started my project and here is my code.
con.Close()
con.Open()
com.CommandText = "SELECT * from math.questions where number ORDER by rand() limit 1"
[code].....
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Aug 18, 2011
I am trying to display value of the field ("UserID") for every row exists in datatable to checkboxlist(make the checkboxlist item selected).
I used for loop, but only the field value from last row of RoleUsers table is selected in the checkboxlist.
Here is my code
Private Sub DisplayRoleUser()
Dim conn As SqlConnection
Dim cmd As SqlCommand
[Code].....
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Aug 16, 2009
I need to use .Select and filtering year on a date field,how can this be done,the next code give me error : the expression contains undefined function call year() vb.net For Each wRwTmp As DataRow In wTblC.Select("year(start_date)=" + wYear.ToString)Next
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Apr 8, 2009
I am getting array of selected datarows from a datatable.select.I use the commands below to get that array or datarows
Dim foundRows() As DataRow
strExpression =
Here is what I tried.I have looked at examples by MS but they all just write to the screen and I have no interest in that.
For Each rowWork In foundRows
dtWork.Rows.Add(rowWork)
Next[code]....
"LineOfBusiness = 'CPP'"
foundRows = modXchange.pdtWork.Select(strExpression)
Now, I want to place the rows from foundrows into an empty data table.I did what I thought was the obvious but that only returns a bunch of rows with no data
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Aug 2, 2011
Unable to select multiple column in datatable
Code:
Dim Activitydtb As DataTable = DirectCast(ViewState("TalentcharacterActivty"), DataTable)
grdviewactivity.DataSource = Activitydtb.Select("SELECT
[Code].....
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Apr 4, 2011
I have a select statement and it will go to a datatable object, I would like to do the following
textbox1.text=datatable(first field value)
textbox2.text=datatable(second field value)
textbox3.text=datatable(third field value)
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Oct 19, 2010
I need to get a button to enter the applications subfolder and randomly select 1 file to be played in the windows media player COM which i have put in the form. I have tried creating a shuffling playlist but i cant get it to stop after one file is played (it just goes on shuffeling to another file, and i really do not want a playlist). I manage to create a batch file to be started to randomly pick a file in that folder, but when i do this the file is being played in the systems default player..
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Dec 22, 2010
I typed this question once already, hit preview, and somehow never got the preview and lost what I typed. It has been that kind of a day.So here is my quick overview then I am going shopping. I am using OLE DB to select from an excel spreadsheet. It has over 15000 rows and 33 columns. Sometimes even when a cell is not null, it is returning a null value. If I just do a "select * where [termination date] is not null", for example, it will return no rows even though I can see with my own eyes that sometimes termination date is not null.
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Mar 3, 2012
I am trying to create an application that will randomly select 14 "stations" (strings) from a list of 33. My thinking is that I have a for/next loop that randomly selects a number between 1,33 which is then inputted into an array (arrnumber) I then want those random numbers to then be used to call the Station name which is saved in the second array, and then for the selected stations to be populated into a listbox (potentially by storing those names selected in a new array?)
Various people have suggested either using a list (of t) instead of arrays, or a Dictionary(?) or perhaps even a database, though I am not all that confident with VB to be able to know where the best place to start with that is. So if anyone can offer any advice, pointers as to how I can link my 2 arrays (I am pretty sure I know how to make the array populate a listbox) I would be very much obliged.
Public Class Form1
Dim Stationid() As String = {"Cardiovascular Examination", "Respiratory Examination", "Abdominal Examination", "Abdominal Examination with Stoma", "Groin and External Genitalia Examination", "Cranial Nerves Examination", "Arm Examination", "Leg Examination", "Parkinson`s Examination", "Cerebellar Examination", "Speech Examination", "Hand Examination", "Elbow Examination", "Shoulder
[code].....
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Aug 16, 2009
So how would I use .next (random numbers) to randomly select something from a list of numbers but it can't repeat the number?I could do:
dim num as integer
dim r as new random
num = r.next(1,5)
if num = 1 then
elseif num = 2 then
etc.
That wouldn't work because it would repeat.If I donwload someone's game can I disect it in VS? :0 I tried going to open project, then I went to the folder and clicked open. It brought me inside of the folder so I tried to open the game but there is no form1 there. It says the games name then .exe in the explorer-like thing in the top right?Also, how would I have a value or something in a label and access it from a button.
Example:This is in a label.
Dim number as Integer
number = 0
Then in the button do
Label.number = 0
How would I do something like that? I want to use that a lot as I did in a different language.
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Mar 6, 2011
I have just about completed a .NET project to write a program to randomly select numbers for a Bingo caller. Over the last month or so Ive learned a lot about .NET but heres something that I consider to be odd and maybe one of you guys can offer an opinion.
One of the features of calling Bingo in a small local club is that callers often use little sayings to accompany certain numbers, I expect youve all heard of (say) All the sixes, clickety click for 66 or 5 and 9 the Brighton line for 59 etc. My little program gives an option to incorporate these with a prompt for the caller that can be edited outside of the program. One of these conventional sayings is used when a number is reversed 12 followed by 21 or 45 followed by 54 for example, when the caller might call (say) 1 and 2, one dozen, number 12 And the other way round 2 and 1, twenty one.
So, I programmed in a bit of code to detect this and to over-ride whatever might otherwise have been the quote with And the other way round and set about testing it. Ive been through literally dozens of full 90 calls watching for the occurrence of a reversed number, spent a few hours doing it, and not once has it occurred which is to say the least, unusual.
So, Im wondering about the Rand Function, could it be that it isnt possible for a reversed number to be selected? Just so you know, I randomly pre-select the order of all 90 numbers, I fill each of the 90 elements of an array with a random number first checking that the number selected hasnt already been stored, if it has, I just get the next random number (and check that too of course), but I cant see how that could prevent reversed numbers being selected, especially in light of the fact that frequently it's not the 'next' number that's used.
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Mar 6, 2012
randomly select a single student out of the student array based on their subscript number. This will be accomplished by the following:
[Code]...
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Oct 4, 2010
I am creating a data logger that pulls data from an existing OPC server. When the data logger is launched, I look into the OPC server and get the names of the sensors that need logging (ColumnNames() as string) . From that, I am creating a data table with columns based on the items in ColumnNames(). That part is working. What I am having problems with is adding rows to the table. When I read the values from the OPC server, I get an array of strings (values() as string) which is guaranteed to be in the same order as the ColumnNames.I have been trying to use an SqlDataAdapter with a dynamically built insert command, but it is getting extremely convoluted and ugly.Is there an way to add a data row to my table using an array of string values directly?
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Apr 21, 2010
Is there a way to determine how many bytes of data are in a DataTable after I've filled it with data from my query?
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Nov 17, 2009
I have a little big problem in one application.
I have a datagridview with data from a datatable, this datatable have these fields (id,num1,num2, date,user,ref,qt,cost,center), some of them are hided in the dgv (id,num1,num2,date,user). The user can edit,delete and add new rows to the dgv.
I have a save button that performs this actions:
First check if there are new rows, and if yes it fill the hidden fields. Then validate the inserted values by the user with a couple of ifs. In the end, i call the bindingsource EndEdit, and call the adapter Update command against the datatable...
This sometimes works others not really, i don't understand why.
The error it's: "Concurrency violation: the DeleteCommand affected 0 of the expected 1 records"
I think sometimes when Updating it occurs to.
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May 7, 2010
I load up a datatable - bind it to a binding source and a binding navigator - and lots of textboxes on the screen bound to that as well.When I get a concurrency violation - another user has already changed my vendor, let's say - what is the best method to go about refreshing the datatable with current data from the DB?
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Apr 4, 2011
I've a xml file to load into the datatable, but no data is loaded, also without any error. the output is 0.[code]
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Sep 29, 2011
I have a Business Logic Layer that contains function that return datatables. I'm writing a function that will return just the records that begin with the string passed in. this is what I've come up with so far:
Public Function FetchBusinessAreas(ByVal area As String) As List(Of BusinessArea)
Dim AreasList As New List(Of BusinessArea)
Dim dt As DataTable
[code].....
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Feb 3, 2011
my .net app output data from sql server to a datatable in my app using executreader.for example:one of the column size in sql server varchar(40),actullay the field only contain 2 chars (like: "AB" for example)when it executes into datatable,it display in the column like "AB" <<this chars + white space = actual size of the column,but I want only the size of the data only, which is "AB" when I export it as csv file the field is >> "AB?
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