.NET (Core and Framework)

19-Jul-07 7:32

I've used StarUML to do C++ and C#. It seems to fit the bill.

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

unique values

n_gchaitra18-Jul-07 17:39

n_gchaitra

18-Jul-07 17:39

Hi,
I am working with asp.net 2.0. I want to check whether the value i have entered in the text box is present in the database or not. If it is present it should not take the same value again. I cant give primary or unique constraint since it might contain many NULL values. How to do this? can i some code for this?

Paul Conrad18-Jul-07 19:29

18-Jul-07 19:29

You could just do a query against the database and count the rows returned. Here is a pseudo-sql statement:

SELECT Count(*) FROM {YourTable} WHERE {YourField} = {YourTextBox.Text}

Where {YourTable} is the table in your database, {YourField} is the field you want to check against, and
{YourTextBox} is the textbox containing the value you are checking.

You have to do the real SQL statement yourself, I am just shedding some light for you.

Hope this guides you in the right direction.

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

n_gchaitra19-Jul-07 2:07

n_gchaitra

19-Jul-07 2:07

Thank u Paul,

I did wrote the code as follows, But did not got any result. What is error i have done.

If dbconn.State <> ConnectionState.Open Then
dbconn.Open()
End If
Dim sqlserial As String
sqlserial = "select count(*) from a_general where serialno='" & txtslno.Text & "'"
Dim cmm As New SqlCommand(sqlserial, dbconn)
Dim dr1 As SqlDataReader

dr1 = cmm.ExecuteReader

If sqlserial > 0 Then
lblmsg.Text = "Duplication of Serial Number is invalid !"
lblmsg.ForeColor = Drawing.Color.Red
lblmsg.Visible = True
Exit Sub
End If

Chaitra N

Paul Conrad19-Jul-07 6:55

19-Jul-07 6:55

n_gchaitra wrote:
dr1 = cmm.ExecuteReader

Maybe should be changed to ExecuteNonQuery instead of ExecuteReader.

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

n_gchaitra19-Jul-07 18:37

n_gchaitra

19-Jul-07 18:37

when i tried to use ExecuteNonQuery it gives the error that, the value type integer cannot be converted to "system.data.sqlclient.sqldatareader"

Chaitra N

Paul Conrad19-Jul-07 18:40

19-Jul-07 18:40

Because executeNonQuery returns the integer number of rows found.

Change

sqlserial = "select count(*) from a_general where serialno='" & txtslno.Text & "'"

to

sqlserial = "select serial from a_general where serialno='" & txtslno.Text & "'"

Concatenation of strings into the query can cause sql injection attacks. Read Colin Mackay's article on this site about those.

Get rid of the dr1 and have an integer for the serial number.

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

Psycho-^*Coder*-Extreme21-Jul-07 18:55

Psycho-^*Coder*-Extreme

21-Jul-07 18:55

n_gchaitra wrote:
dr1 = cmm.ExecuteReader

Change this to dr1.ExecuteScalar. Use ExecuteScalar when returning only a single value from the database.

"Let's face it, the average computer user has the brain of a Spider Monkey."
Bill Gates

Pete O'Hanlon20-Jul-07 4:43

Pete O'Hanlon

20-Jul-07 4:43

Sorry to butt into your thread here, but there is a problem with this architectural approach. Suppose you have two users typing in values, and they both enter the same value. User 1 does the check to see if it's present and it says "Nope - ok to enter it here" because the row count is 0. User 2 does the check to see if it's present and it says "Nope - ok to enter it here" again, because the row count is 0. However, User 1 now inserts it into the table. When the code for User 2 attempts to insert the record, it is now duplicated.

Deja View - the feeling that you've seen this post before.

Paul Conrad21-Jul-07 18:34

21-Jul-07 18:34

Pete O'Hanlon wrote:
Sorry to butt into your thread here

No worries. Didn't really think of any race condition occurring. Could do some kind of record locking through the app, but even if he could mark the record as being currently in use, there could be a race condition on that, too...

"Any sort of work in VB6 is bound to provide several WTF moments." - Christian Graus

Using Reflection to iterate through a collection object?

Urs Enzler22-Jul-07 6:34

Urs Enzler

22-Jul-07 6:34

Have a look here: http://blogs.msdn.com/sqlcat/archive/2005/12/20/506138.aspx

-^-^-^-^-^-
no risk no funk

twista17-Jul-07 23:01

twista

17-Jul-07 23:01

Hi,

I've been trying to work out how to iterate through a collection object using reflection.

I have a class with a few simple objects, strings, single[] arrays, and one collection.

However, when I'm using the GetFields() method to retrieve the objects in my class, when it gets to the collection I am unable to view all the items in the collection.

dim coll as collection = FieldInfoObj.getvalue(obj)
console.writeline("Collection has " & coll.count & " items in the collection")
for each item as object in coll
do_stuff(item)
next

Although it correctly states that I have 4 items in the collection, item 1 is Ok. item 2 is 'nothing' and item 3 causes an error. But I do actually have 4 'singles' in the collection.

How do i access the collection objects using reflection?

I *think* I need to reflect into each object seperately, and not just iterate through them after setting the main collection object using the getvalue(obj) method as I would with the other system.xxx type objects (which work fine)

Could anyone provide a simple example of how to iterate through a collection using reflection?

Thanks in advance,
Phil.

Re: Using Reflection to iterate through a collection object?

Urs Enzler22-Jul-07 22:29

Urs Enzler

22-Jul-07 22:29

What I don't understand is why you want to use reflection to loop through the items.

Why not test the collection if it is an IEnumarable and loop through the items with a normal foreach() statement. And afterwards use reflection to reflect into each single item?

-^-^-^-^-^-
no risk no funk

Re: Using Reflection to iterate through a collection object?

twista25-Jul-07 23:55

twista

25-Jul-07 23:55

The problem I was having was that the collection object said that it had 4 items in its collection, but the for each loop was only getting back the first, the second being "nothing" and the third and forth missing completely.

Actually the problem was that I was using a db4o database and had not "activated" the object completely so when my collection object was given back from db4o, half of the collection object was missing!

After getting back the entire object from the database correctly, I can now go through the collection Smile | :)

I'm using reflection to examine the object as the program does not know anything about that object (plugin) - when it got to a "collection" object, the program broke and I was thinking that I was doing something wrong with reflection on a collection object. Although as you've pointed out, if its a collection object, you should just be able to loop through them and reflect on the objects it passes back. Smile | :)

Ah the joys of db4o Smile | :)

.Net 3.0 installation always fail

George_George16-Jul-07 21:49

16-Jul-07 21:49

Hello everyone,

I am using installer from,

http://www.microsoft.com/downloads/details.aspx?familyid=C2B1E300-F358-4523-B479-F53D234CDCCF&displaylang=en#AdditionalInfo

on Windows XP SP2 machine. The installer always report an error (and pops up the popular message box of sending an error message to Microsoft). I have tried on two machines and the error is the same. But I do not know where to check the exact error log.

My questions are,

1. This package is for Windows XP SP2 or only Windows Vista?
2. Is it mandatory needed if I want to use Visual Studio 2005 + .Net 3.0 to do C# development?
3. Anyone has met with similar issues before?

thanks in advance,
George

Akhilesh Yadav17-Jul-07 0:09

Akhilesh Yadav

17-Jul-07 0:09

1. This package is for Windows XP SP2 or only Windows Vista?

>> I think there is another SP avialble for using .net 3.0

2. Is it mandatory needed if I want to use Visual Studio 2005 + .Net 3.0 to do C# development?

>> No Not at All

--Akki

George_George17-Jul-07 0:42

17-Jul-07 0:42

Thanks Akki,

>> I think there is another SP avialble for using .net 3.0

Can you provide an URL please? I think you mean there is a .NET SDK 3.0 for Windows XP + Visual Studio 2005?

>> No Not at All

My application is not using the new functions in .Net 3.0 (e.g. workflow) and only utilize the common functions. In this situation, my purpose is to test whether my application works with .Net 3.0 Runtime.

Do you think in my situation, I need to build my application again using .Net SDK 3.0? Or just using the old build (built by .Net 2.0) and run it in .Net 3.0 Runtime environment?

(I still doubt whether there are any differences in my application build, if I choose to use 2.0 SDK or use 3.0 SDK?)

regards,
George

Kevin McFarlane17-Jul-07 0:25

17-Jul-07 0:25

First, I assume you already have .NET 2.0 installed? If not, you'll need that.

I also installed this Microsoft .NET Framework 3.0 Redistributable Package[^]

Then I installed the .NET 3.0 SDK some time later. You don't necessarily need it. I was doing mostly Workflow Foundation which only required the .NET 3.0 Redistributable + the Workflow Extensions designer. It was only when I did an experiement with WCF that I needed a utility that was in the .NET 3 SDK.

George_George wrote:
Is it mandatory needed if I want to use Visual Studio 2005 + .Net 3.0 to do C# development?

It depends which bits you want to use. For WF you just need the .NET 3 redist + WF Desiner.

Kevin

George_George17-Jul-07 0:37

17-Jul-07 0:37

Thanks Kevin,

Yes, I installed .Net 2.0 both SDK and Runtime with Visual Studio 2005. I am using common (old) functions between .Net 2.0 and .Net 3.0 using C#, so I think there is no need to install the SDK from? Right?

http://www.microsoft.com/downloads/details.aspx?familyid=C2B1E300-F358-4523-B479-F53D234CDCCF&displaylang=en#AdditionalInfo[^]

So, I just build my application using previous (.Net 2.0 environment) and test it with .Net 3.0 Runtime?

regards,
George

Kevin McFarlane17-Jul-07 1:38

17-Jul-07 1:38

Unfortunately, Microsoft have created confusion with their naming. There is no .NET 3 runtime as such. Everything uses the .NET 2 runtime. .NET 3 refers to .NET Framework 3 which is essentially just a bunch of new classes for WF, WCF, SPF and WCS. So you don't need to install .NET 3 at all if you're not going to be using any of WF, WCF etc.

Kevin

George_George17-Jul-07 2:28

17-Jul-07 2:28

Thanks Kevin,

I want to setup Runtime environment to make some tests. For a machine which is empty (.Net 2.0 is not installed), I think I should install the following Runtime SDK to enable .Net 3.0, right?

http://www.microsoft.com/downloads/details.aspx?FamilyId=10CC340B-F857-4A14-83F5-25634C3BF043&displaylang=en[^]

Any need to install .Net 2.0 Runtime before install the Microsoft .NET Framework 3.0 Redistributable Package?

regards,
George

Kevin McFarlane17-Jul-07 2:38

17-Jul-07 2:38

George_George wrote:
Any need to install .Net 2.0 Runtime before install the Microsoft .NET Framework 3.0 Redistributable Package?

Yes.

Kevin

George_George17-Jul-07 3:11

17-Jul-07 3:11

Thanks Kevin,

I have tested that Microsoft .NET Framework 3.0 Redistributable Package will install .Net 2.0 Runtime (like System.Data.dll) automatically, no need to install .Net 2.0 Runtime in advance.

regards,
George

Kevin McFarlane17-Jul-07 3:24