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Jay,
The preferred MS access method is to connect, retrieve multiple rows if possible, and then close the connection. As noted ADO Connection pooling is great for this. If you prefer working with embedded SQL you can definitely use ODBC in this manner: basically create an adapter and fill your dataset. Fundamentally you have to choose the direction you want to go with that makes the most sense to you. Bear in mind the more layers we add to "simplify" our logic isn't always the most straightfoward solution at the end of the day.
Now having a database proxy is another approach. Like the other cases I'd say you definitely need to ditch the one connection approach and support some "configurable" number of connections to allow for tuning. Ideally a proxy would have a multi-threaded or async architecture as the core einfrastructure. You can also build in security as needed. There are plenty of TCP/IP examples on Code Project that do this type of thing. All you would need to do is provide the Glue to make it ft within your world.
I personally use ODBC with MySQL and have found the development to be pretty easy. One of the hassles is the DSN, i.e. do you want to provision it in odbcad32 on each system or... provide some automated form of registry loading? Again here's a cat that has been skinned many times on Code Project.
I'll briefly mention OLE DB which is Micosoft's supplement to ODBC. Basically yet another access method but this one is not aimed at relational databases per se, but if you have to retrive from other data stores such as ISAM files, MS Office Files, then it' worth investigating.
Good luck
Mike Luster
CTI/IVR/Telephony SME
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hi am called brian
first of its not good to use only one connection in your application especially if your application is going to be a mull-ti user.but if it is a single user kind then its ok.
the easiest way of creating connections is
1] go to the solution exp on the right hand side of of the V.S window
and double click on the on the properties link it will open a window that contains the application settings but you select the settings option
then create your connections that is any no you want
eg(connection,ConnectionString,Select the data source)
1)in the first dropdown you create the connection name
2)in the second dropdown you specify the connection type(Connection String)
3)you select the Data source
2]to access them you will use this the following code
//create a variable[connecition]
SqlConnection connection=new SqlConnection ();
//use it to implement he connection string
connection.ConnectioString=Properties.settings.default.ConnectionString;
try that out
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Hi 
I wanted to store word documents in my SQL server, so i have stored them as images. Now I want to be able to open these documents after clicking a hyperlnk in a datagrid.
Is this possible? Can someone show me how to do this? 
Thanks for your help.
melissa
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You need to make a proxy page that gets the data from the database and sends it to the browser using Response.BinaryWrite.
---
b { font-weight: normal; }
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Thanks for replying Guffa!
So once clicking the link, the user is taken to a proxy page with the document?
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Hi
I used Response.BinaryWrite to write to a blank webpage.
When i'm writing a jpg, it shows up great. but because i'm actually storing word documents as binary, i get all these funny symbols when i'm displaying it on a webpage. is there some other way to store word docs in sql server, and then being able to open/save them?
Thanks heaps!
melissa
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Set the ContentType of the response according to the file type so that the browser can recognise it and choose the correct program to open it.
---
b { font-weight: normal; }
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how to solve error below....
Error in File C:\DOCUME~1\GIGA-G7\ASPNET\LOCALS~1\Temp\temp_3797143f-fd73-493e-9e15-41986f48b6d6.rpt: Error in formula <record_selection>. '{Command.subCode} = WXES 3182 AND {Subject.subName} = Thesis AND (Lecturer.lecturerName) =abc AND {Command.subSession} = 2005/2006 AND {Command.semester} = 2 AND {Subject.faculty} = FSKTM' A number, currency amount, boolean, date, time, date-time, or string is expected here.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: CrystalDecisions.CrystalReports.Engine.FormulaException: Error in File C:\DOCUME~1\GIGA-G7\ASPNET\LOCALS~1\Temp\temp_3797143f-fd73-493e-9e15-41986f48b6d6.rpt: Error in formula <record_selection>. '{Command.subCode} = WXES 3182 AND {Subject.subName} = Thesis AND (Lecturer.lecturerName) =abc AND {Command.subSession} = 2005/2006 AND {Command.semester} = 2 AND {Subject.faculty} = FSKTM' A number, currency amount, boolean, date, time, date-time, or string is expected here.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[FormulaException: Error in File C:\DOCUME~1\GIGA-G7\ASPNET\LOCALS~1\Temp\temp_3797143f-fd73-493e-9e15-41986f48b6d6.rpt:
Error in formula <record_selection>.
'{Command.subCode} = WXES 3182 AND {Subject.subName} = Thesis AND (Lecturer.lecturerName) =abc AND {Command.subSession} = 2005/2006 AND {Command.semester} = 2 AND {Subject.faculty} = FSKTM'
A number, currency amount, boolean, date, time, date-time, or string is expected here.]
. F(String , EngineExceptionErrorID
)
. A(Int16 , Int32 )
. @(Int16 )
CrystalDecisions.CrystalReports.Engine.FormatEngine.GetPage(PageRequestContext reqContext)
CrystalDecisions.ReportSource.LocalReportSourceBase.GetPage(PageRequestContext pageReqContext)
CrystalDecisions.Web.ReportAgent.u(Boolean N)
CrystalDecisions.Web.CrystalReportViewer.OnPreRender(EventArgs e)
System.Web.UI.Control.PreRenderRecursiveInternal()
System.Web.UI.Control.PreRenderRecursiveInternal()
System.Web.UI.Control.PreRenderRecursiveInternal()
System.Web.UI.Page.ProcessRequestMain()
angela
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I don't know if there is a way to do what I am about to describe so please tell me if it can or can not be done. I have done some searching but have found nothing similar to what I want.
As a simple example lets say I want to create a class to impliment linked lists. I want to have doubly and singly linked lists available, but the only public class I want to have is LinkedList. Ok, so a singly linked list is a subset of a doubly linked list, so there is nothing it can do a doubly linked one could not do. So you ask.. "eggsovereasy, just make a doubly linked list class and it can handle the singly linked ones". To which I respond that I think it would be clean were only the methods and properties pertinent to the type of LL you want made accessible.
So, the method to add a node in a DLL would look like:
Add(Node<T> prevNode, T data)
and a SLL like so:
Add(T data)
The two input method would not even be accessible if you set the "Type" property on LinkedList to "Singly".
I don't think this can be done, but it would cool if it could.
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Make an abstract class with 2 static methods, and 2 classes deriving:
public abstract class LinkedList<T>
{
public static LinkList<T> GetDoubleLinked()
{
return new DoubleLinked<T>();
}
public static LinkList<T> GetSingleLinked()
{
return new SingleLinked<T>();
}
}
public class DoubleLinked<T> : LinkedList<T>
{
}
public class SingleLinked<T> : LinkedList<T>
{
}
And instantiate like this:
LinkedList<string> singleLinked = LinkedList<string>.GetSingleLinked();
LinkedList<string> doubleLinked = LinkedList<string>.GetDoubleLinked();
At this point, you have references to 2 objects that seem alike, but are not.
[Edit] I forgot to mention, make the constructors (any contructor) of the 2 derived classes, apply the internal modifier to them, so no external class can instantiate them directly, if this is what you want. [/Edit]
--------
"I say no to drugs, but they don't listen."
- Marilyn Man
-- modified at 22:10 Wednesday 8th March, 2006
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Ok, forgot about the Add methods.
I think you Node class should be built the same way. An abstract Node, and 2 other classes, SingleNode, and DoubleNode.
So, you could have 2 methods in LinkedList<T>:
public abstract Node<T> GetNode(T data);
public abstract void AddNode(Node<T>);
Those 2 methods are overriden by the 2 other linked list classes, each override returning an appropriate kind of Node.
Single override:
public Node<T> GetNode(T data) { return new SingleNode<T>(data); }
Double override:
public Node<T> GetNode(T data) { return new DoubleNode<T>(data); }
It may sound a lot of work, but this is the only way to achieve the level of encapsulation you want.
--------
"I say no to drugs, but they don't listen."
- Marilyn Manson
-- modified at 22:22 Wednesday 8th March, 2006
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I'm trying to write OLE in-place activation server app in C#. Basically, what I want is that a user should be able to do Insert -> Object... in Microsoft Word and select my object there.
Has anybody done this? What interfaces do I need to implement? A non-C#/.NET-specific how-to will also do.
Thanks,
Nikhil
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Hi!
How can I create a program that works just like a normal Windows Service for Windows CE (Pocket PC)?
I need the program to autostart when the operating system loads, and to do its work without making the user aware of it.
thanks!
/spAAwn
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Hi. I need to iterate through every file in directory.
Geting files first into array with Directory.GetFiles() is too slow. How can I manualy iterate through files?
Thx
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Go to this site:
http://www.libertyassociates.com/pages/Books.htm[^]
and download the source code for Programming C# 3rd edition (near the bottom of the page)
Ex 21-02 "Exploring files and subdirectories" in the Chapter 21 folder is a good example to study. And in general there's lots of useful examples in the book. (The 4th edition book covers C# 2.0.)
Kevin
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Hey guys,
I think about to add a checkbox to the standard openfiledialog, but I didn't find a way to do that. Do anybody know if it's possible to "customize" the openfiledialog? And how?
Ralf
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Make a class that inheriets the OpenFileDialog and add your checkbox and extra logic there...
Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!
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This could be possible if OpenFileDialog wasn't sealed.
There are some tutorials to add extra fields to the dialog but can't find them right now.
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Thanks,
but I think it's not possible to inherit because it's a sealed class.
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Hi,
Say i have a class User with some public properties
-FirstName
-LastName
-Email
I then load an ArrayList (arrUsers) with User objects and set a DataGrid's datasource = arrUsers.
The grid will create three columns (FirstName,LastName,Email) and fill them with data.
What i really wonder is if there's a way to control which properties in the User object the datagid will use.
Maybe an attribute or implementing an interface. Setting the properties to private isnt good enough nor is creating the datagrid's columns with a datafield.
Niclas Ahlqvist
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Is there a place on the web that cna show some samples or give ideas of different types of user interfaces?
Thanks
Tom Wright
tawright915@yahoo.com
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DesigningInterfaces.com[^]. While the page itself is somewhat of an advertisement for the book, the site contains many free UI examples and patterns applicable to both desktop and web apps (see the links on the left of the page).
Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Lent Revisited
The apostle Paul, modernly speaking: Epistles of Paul
Judah Himango
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I tried two ways of obtaining drive letters, one using Directory.GetDriveNames() and the other using ManagementObjectCollection. In both cases, my app checked the A drive and sometimes also D drive. This caused that terrible noise from diskette drive or/and a "no media in drive" dialog appeared every time the application is launched.
I can just skip the problematic "A" and "D" drives, but this is a dirty solution, because not all users have A,C,D drive letters.
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I would have to disagree....a little on that.
Most computers come with a floppy, a harddrive, and a CD-ROM. If so they will always be A, C, D respectively. While you can purchase some computers without a floppy or a CD-ROM, almost 90% of the time you will not. Why? How else will you install the OS is need be without removing the harddrive?
Tom Wright
tawright915@yahoo.com
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Floppies are becoming sparse on newer machines, many oems are including an X-in-1 card reader instead. A bootable CD will install the OS without need for a floppy. Enough are also putting recovery data on a 2nd partition instead of, or in addition to a floppy that even on oem boxes assuming D for the CD is chancy. Self build machines often have multiple HDs as well, my personal machine has cd drives at H and I due to partition based data segragation and multiple harddrives.
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