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I am working on this program where i need to supply the name of the server at runtime so as to dynamically build the connection string..
what I am saying is that..the program will have a initial setup screen, so the user can supply the name of the server...
how do i go about doing that..presently i am using local and at times i use the name of my server..but i need to use the program on different computer on a network, which i am not sure of the server name at this moment...can anyone help.. I hope this was clear..
i am using sql server 2000 and vb.net 2003 as my front end...
Nab
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Not sure what you are into but here is a pretty handy website to get the connection strings link
Are you using the application blocks from MS or are you using your own.
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Ok thank you guys. But can any one help me with this? My program would have a initial setup screen where the system admin will suply all the necessary informatoin such as the server name, pasword, username and stuff like that... all this information would be written to a text file somewhere on the hard drive. The program should then take the server name, user name and password from the text file to create the connection string to connect to the database (sql 2000)
How do i go about using the information from the text file to create my connection string so that my program can use it? I can't program the connection string in the project because i don't know the name of the server they will be using and they might need to put it on other servers..
Please help!!
Nab
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Ok here you go but let me tell you up front that I would never do this in any production code Ever and here is why. If you persist the connection to a local file you can/will get hacked and you now have the responsiblity of maintaining or validating the contents of the file. So based on this don't use this code in production applications it is to dangerous and you don't need to there are better options. If the user has to enter the server username and password just hold it in a member variable then all of the problems go away.
This is a test form to prove the concept
Public Class Form1
' Member sqlConnection variable
Private mConnString As Data.SqlClient.SqlConnection
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' Gives you the path of the file to write
Dim csExample As New connectionstringexample("C:\connectString.txt")
' Builds the structure and stores the data to a file
csExample.PersistConnectionString(New ConnectionStringStuct("myServerAddress;myDataBase;myUsername;myPassword;"))
Try
' Instantiates the new connection string using the data retrieved from the file
mConnString = New System.Data.SqlClient.SqlConnection(csExample.GetConnectionString())
Catch ex As Exception
Throw New ApplicationException(ex.Message)
End Try
End Sub
End Class
I used a structure to hold the data because it keeps everything by value
not by reference. It has two fields one with a formatted connectionstring and one that is the raw delimited data which should be encrypted.
Public Structure ConnectionStringStuct
' Real work is done here
Sub New(ByVal RawStringIn As String)
Dim lStringParts As String() = RawStringIn.Split(";")
' Put any validation code here
' Buids a complete connection string
mConnectionString = "Data Source=" + lStringParts(0) + ";" _
+ "Initial Catalog=" + lStringParts(1) + ";" _
+ "User=" + lStringParts(2) + ";" _
+ "Password=" + lStringParts(3) + ";"
mRawString = lStringParts(0) + ";" _
+ lStringParts(1) + ";" _
+ lStringParts(2) + ";" _
+ lStringParts(3)
End Sub
Private mConnectionString As String
Private mRawString As String
Public ReadOnly Property ConnectionString()
Get
Return mConnectionString
End Get
End Property
Public ReadOnly Property RawString()
Get
Return mRawString
End Get
End Property
End Structure
The responsibility of this class is to manage the use of the structure and do the IO work and is not responsible for any data related to the connection string.
Public Class connectionstringexample
' Signiture of the Connection String
'Data Source=myServerAddress;Initial Catalog=myDataBase;User Id=myUsername;Password=myPassword;
Sub New(ByVal FilePath As String)
mFilePath = FilePath
End Sub
Private mFilePath As String
Public Function GetConnectionString() As String
Dim rtn As String = String.Empty
Dim lConnectionString As String()
Dim lConnectionStringStructure As ConnectionStringStuct
Try
' Get the data from the file
lConnectionString = System.IO.File.ReadAllLines(mFilePath)
' Create the structure and get the data organized
lConnectionStringStructure = New ConnectionStringStuct(lConnectionString(0))
' Send out the return value
rtn = lConnectionStringStructure.ConnectionString
Catch ex As Exception
Throw New ApplicationException(ex.Message)
End Try
Return rtn.ToString()
End Function
Public Function PersistConnectionString(ByVal ConnectionStringIn As ConnectionStringStuct) As Boolean
Dim rtn As Boolean = False
Try
'Writes the RawFormated string to the file
System.IO.File.WriteAllText(mFilePath, ConnectionStringIn.RawString)
rtn = True
Catch ex As Exception
Throw New ApplicationException(ex.Message)
End Try
Return rtn
End Function
End Class
So there is an example but let me encourage you to find and use the microsoft application blocks they are free and very stable. You can extend them to handle your special needs and it gives you a great place to start from instead of building you own code base.
Just to make the point you do not need to persist this to a file just create an instance of the structure using the input from the app when the user provides the connection inputs. By the way .Net 2.0 has some richer features to help with building connection strings so take a look at them when you get a chance .
Hope this helps.
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There's nothing special about building a connection string. It's a normal string just like any other and can be built using the exact same methods.
Dim connStr As String = String.Format("Data Source={0};Initial Catalog.....", serverName)
Dave Kreskowiak
Microsoft MVP - Visual Basic
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I need to sort an array but I also need to keep track of where each array item was in the array before it was sorted. I was wondering if anybody knew of a built in vb.net function that would give me a sorted array and an array with its original index number.
Thank you for your help,
Mike
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There is nothing that will do it for you. You have to maintain two copies of the array yourself. There is nothing in the .NET Framework that will do it for you. The first is your original, unsorted version. The second is a copy of the first one, but sorted.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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You may sort the array using a further level of indirection, i.e. suppose you have myArray(10) the you use another array index(10) of integers and sort myArray so that myArray(index(i+1)) > myArray(index(i)). Having done that you retain the original values in myArray.
hope that helps.
-- modified at 9:22 Saturday 30th December, 2006
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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I am trying to connect to a MySql database using vb.net but I keep getting this error:
An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
Here is my code:
Dim TimeStamp As String
TimeStamp = Format(Now(), "dd/MMM/yyyy HH:mm")
Dim myConnString As String = "Data Source=testship;User Id=jsimmons;Password=dway1207;"
Dim myInsertQuery As String = "INSERT INTO ls_orderitems (OrderItemID, OrderDate, OrderCustomer, OrderAcctNum, OrderType, OrderSoNum, OrderItemPartNum, OrderItemPartDesc, OrderItemQty, OrderItemQtyRec, OrderItemQtyDtRec, OrderItemBO, OrderItemBODt,OrderItemCanceled, OrderItemCanceledDt, OrderItemNotes, OrderItemPONum, OrderItemRetailPrice, OrderItemSalePrice, Status, InsertDate) VALUES('" & Trim(OrderItemID) & "','" & Trim(OrderDate) & "','" & Trim(OrderCustomer) & "','" & Trim(OrderAcctNum) & "'," & "'" & Trim(OrderType) & "'" & ",'" & Trim(OrderSoNum) & "','" & Trim(OrderItemPartNum) & "','" & Trim(OrderItemPartDesc) & "','" & Trim(OrderItemQty) & "','" & Trim(OrderItemQtyRec) & "','" & Trim(OrderItemQtyDtRec) & "','" & Trim(OrderItemBO) & "','" & Trim(OrderItemBODt) & "','" & Trim(OrderItemCanceled) & "','" & Trim(OrderItemCanceledDt) & "','" & Trim(OrderItemNotes) & "','" & Trim(OrderItemPONum) & "','" & Trim(OrderItemRetailPrice) & "','" & Trim(OrderItemSalePrice) & "','" & Trim(Status) & "','" & Trim(InsertDate) & "','" & TimeStamp & "'" & ")"
Dim myConnection As New SqlConnection(myConnString)
Dim retvalue As Integer
Dim myCommand2 As New SqlCommand(myInsertQuery, myConnection)
myConnection.Open()
retvalue = myCommand2.ExecuteNonQuery()
myConnection.Close()
Any advice will help.
jds1207
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You say you're using MySQL, but your code say's your using SQL Server. Which is it? You can't use the Sqlxxxx objects on a MySQL server, you have to use the OleDbxxxx objects instead.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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You need to go into the Sql Server Configuration Manager and set it up to allow remote connections.
jds1207 wrote: MySql database using vb.net ... error:
An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005
MySQL and SQL Server 2005 aren't the same database
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I do not know how to do this project
please help
I do not how to do the code
<the project="" is:="" create="" a="" name="" backwards="" application="" that="" prompts="" the="" user="" to="" enter="" his="" or="" her="" (in="" textbox="" not="" inputbox)="" and="" then="" displays="" in="" all="" lowercase="" label="">
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Don't think of the name as a name but instead a collection of char's.
The StringBuilder object will take the text and allow you to reference each char in it using it's position in the array.
So when you create an newSB as new stringbuilder("abc")
what you really have is
newSB(0)=a
newSB(1)=b
newSB(2)=c
Now if we went old school(kind of)
you would create an arraylist newSA as new arrayList()
'This loads the ArrayList up
For ctr As Integer = 0 To Label1.Text.Length - 1
newSA.Add(Label1.Text.Substring(ctr, 1))
Next
' This unloads the ArrayList into a label stepping down the arraylist
For ctrOut As Integer = sa.Count - 1 To 0 Step -1
Label2.Text += newSA(ctrOut).ToString()
Next
This sounds very much like homework but you cannot just brush over this it is to important. What you are exploring is how the variables are really just memory locations and you can address them many different ways. To prove the point lets shrink the example.
' This unloads the TextBox into a label stepping down the String
For ctrOut As Integer = TextBox.Text.Length - 1 To 1 Step -1
Label2.Text += TextBox.Text.Substring(ctrOut, 1)
Next
So there you go a lengthy discussion on what strings are but if you are going to learn how to program get to the real meaning of what they are asking you to learn.
Hope this Helps
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I have just completed a course in programming VB.NET with DeVry and I really like it. I want to write a program for a blackjack game. I have 2 arrays set up for the deck of cards, one for the card name (ex. 3-Hearts) and the other for the card value (ex. the 3-Hearts = 3).
I'm starting small and I only want to deal 2 hands (user and dealer). My question is:
Is there a better way to generate 4 random numbers from 1 - 52 so that you do not get the same number twice? Of course, for drawing other cards in the hand I'll need additional random numbers.
This is what I have and it seems to work, but is there another (better, shorter) way?
Randomize() 'Initialize random number generator.
Do
intCard1 = CInt(Int((51 - 0 + 1) * Rnd() + 0)) 'Random generate 1st number.
intCard2 = CInt(Int((51 - 0 + 1) * Rnd() + 0)) 'Random generate 2nd number.
Loop Until intCard1 <> intCard2 'Loop if cards are the same.
Do
intCard3 = CInt(Int((51 - 0 + 1) * Rnd() + 0)) 'Random generate 3rd number.
Loop Until intCard3 <> intCard1 And intCard3 <> intCard2
Do
intCard4 = CInt(Int((51 - 0 + 1) * Rnd() + 0)) 'Random generate 4th number.
Loop Until intCard4 <> intCard1 And intCard4 <> intCard2 And intCard4 <> intCard3
Thanks in advance for any assistance!
Mike
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The trick is simulating what happens in real world.
Suppose you have to extract five (distinct) numbers from fifty ones.
You first initialize an array
For n=1 to 50
num(n)=n
next n
then you extract the five numbers into the extracted array
for k=0 to 4
r = CInt(50 * Rnd() + 1 - k))
extracted(k) = num(r)
swap(num(r), 50 - k )
next k
As you can see, each time the extracted value is swapped with the element at the and of the array and the following choice is done on a narrowed array.
Hope that helps (I wrote the code remembering the algo, i.e. I did not verify it, only to illustrate the algo itself).
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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Thanks for the prompt response. I thought I would try a small program using your suggestion just to see if I could generate the random numbers to a msgBox, but I get the dreaded blue squiggly line under "swap" and the message says that the "expression is not a method". Any ideas on this?
Thanks again,
Mike
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If there is no method to swap two variables then you have to manually swap them, i.e.
swap(a,b)
is equal to the following statements:
tmp=a
a=b
b=tmp
where tmp is a temporary variable.
hope that helps
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
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This is the error message that i receive when i go to run the program.
Windowsapplication1 has encountered a problem and must shut down.
Error Signature:
EventType: clr20r3 P1:applaunch.exe P2: 2.0.50727.42
P3: 4333ab62 P4:starch P5:1.0.0.0 P6: 45952711 P7:e
P8: e9 P9:system.invalidoperationexception
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There's no way to tell from that information. There's LOTS of possible causes, including making cross-thread calls in .NET 2.0 that are no illegal but worked fine under .NET 1.x. Messing up the references section of your code. Interdependencies of any controls your using, like using the Office 11 PIA's and only having Office 10 installed. Controls that depend on other libraries that don't exist on the target machine. ...
Dave Kreskowiak
Microsoft MVP - Visual Basic
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anyway to further identify the problem?
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Nope. The data that's in the message is just the data of the message itself.
If you can get a debugger attached to it you're well on your way to finding the cause. The problem is that most of the time, this error happens right at startup, which would lead me to believe that there is a dependancy problem.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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ok so this might be a stupid question, but how do i go about getting a debugger attached to the program
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Create a test machine that replicates the problem, then install VS.NET on it. Or setup a remote debugging session so you can attach your development machine to the process on a remote machine. But, you have to launch the code to get the process running before you can attach the debugger to it. Like I said, if it crashes immediately upon launch, you're not going to get a debugger going and attached.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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Hi all,
Can I run vb code and com components in Unix, Lynux and Solaris operating systems. I need complete information
Thank you,
S/W Engineer
Akebono Soft Technologies
aleem_abdul@akebonosoft.com.
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No.
Dave Kreskowiak
Microsoft MVP - Visual Basic
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