Web Development

Daniel Turini7-May-02 23:13

Daniel Turini

7-May-02 23:13

In most languages that properly supports them (e.g. SQL), null values are a kind of "dead end" values. Every expression that involves a null value should become null or a type cast error. It varies from language to language what's a type cast error or a null, but the principle is the same:

So, Null + 12 results Null
Null * 2 results Null
Null == 12 results Null.
Null == Null results Null.

Well, VBScript automatically casts Null to a boolean False, so both checks fail.
Try with SQL (any decent SQL implementation) and you'll get the same results.
In fact, in SQL you should use "IS NULL" and not "= NULL" in queries. This is a common bug I see.

Crivo
Automated Credit Assessment

Philip Patrick7-May-02 23:27

7-May-02 23:27

Yep, I realized that. The last language I still didn't checked is Pascal (let me come home, I'll do that Smile | :)

)

Now I see, that developers of programming languages thought about humans and not about computers and Math.
Null <> 12 should be True and doesn't matter what you mean by Null. But someone assumed that all operations with Null should return Null. I can't accept it, because it is a human's view, not computer's Smile | :)

So again.... C++ Rulez (sorry for kidding Smile | :)

)
In C++ NULL != 12 is true as it should be Smile | :)

Philip Patrick
Web-site: www.stpworks.com
"Two beer or not two beer?" Shakesbeer

Need Web-based database administrator? You already have it!

James T. Johnson7-May-02 23:38

7-May-02 23:38

Philip Patrick wrote:
In C++ NULL != 12 is true as it should be

Ah, but in C++ NULL HAS a value (0 or (void*) 0), NULL should not have a value because that is what it means, no value.

When you compare something to NULL in C++ you are checking whether the pointer is pointing to memory location 0.

James

Simplicity Rules!

8-May-02 1:06

Any Null operations will result in Null (e.g. Null<>12=Null and [Null=12]=Null)...and in If null is coerced into False

Philip Patrick8-May-02 1:13

8-May-02 1:13

Well, many people (and myself also) already said this.
Now another question. If you can't compare to Null, so why you can cast it to Boolean? Smile | :)

And if you can cast Null to Boolean, you can or sure cast it to Integer. So the result should look like (I'll use C++ syntax, it has castings)

if( ((int)(bool)NULL) <> (int)12 ) ...

You see now? You can compare to Null Smile | :)

Maybe I'm stubborn, but still it doesn't make sence to me Smile | :)

Philip Patrick
Web-site: www.stpworks.com
"Two beer or not two beer?" Shakesbeer

Need Web-based database administrator? You already have it!

Philip Patrick8-May-02 1:07

8-May-02 1:07

James T. Johnson wrote:
NULL should not have a value

Why not? You can't implement it in computer without some sort of philosophy. If no one knows what is NULL, so why it is not 0? Smile | :)

Again, it doesn't matter what it is, 0 or -1 or 980987. You have to agree that Null (whatever it be) is not 12 Smile | :)

Philip Patrick
Web-site: www.stpworks.com
"Two beer or not two beer?" Shakesbeer

Need Web-based database administrator? You already have it!

James T. Johnson8-May-02 1:29

8-May-02 1:29

Philip Patrick wrote:
Why not?

That is the definition of NULL when dealing with databases, no value. To give a value to NULL is a hack.

Philip Patrick wrote:
If no one knows what is NULL, so why it is not 0?

We know what NULL is, NULL is the state of not having a value Smile | :)

Philip Patrick wrote:
Again, it doesn't matter what it is, 0 or -1 or 980987

Sure it does, if Age is a nullable column in a database an age of 0 has a different meaning than no value. That is its entire purpose.

Philip Patrick wrote:
You have to agree that Null (whatever it be) is not 12

In the original post you were using equals to compare two values, any value compared to Null is Null, not true or false; but thanks to VB's implicit casting [ Mad | :mad:

] you get a false out of it.

Something I neglected to mention in my previous post was the Database NULL and C++ NULL stand for two different things. Database NULL means no value, C++ NULL means a pointer to memory location 0, obviously a value.

James

Simplicity Rules!

Philip Patrick8-May-02 1:53

Some 100 % beginner ASP.NET tutorials PLEASE!

8-May-02 1:53

James T. Johnson wrote:
any value compared to Null is Null

And this is what I don't understand. Why it is Null? I mean the result of comparision. If it is illegal to compare to Null, so I should get an error, but not a boolean "False" Smile | :)

At the end I don't understand what is "nothing" in computer?

Confused | :confused:

Philip Patrick
Web-site: www.stpworks.com
"Two beer or not two beer?" Shakesbeer

Need Web-based database administrator? You already have it!

Query Excel Sheets Count

serberwww6-May-02 22:08

serberwww

6-May-02 22:08

Hello.
I need query Excel Sheets count and names
by asp.net.
How can I get access to a Excel file and it's
properties?

Can anyone help me?
Thanks in advance!!!!
Sergio

Sergio Bertini

ASP Forum Code

sriani6-May-02 9:00

sriani

6-May-02 9:00

Hi Recently I have downloaded the Advanced ASP Forum and Discussion board with Integrated Members System. Could you please tell me how to demo the code. I am new to this area and trying to understand the code.

Thanks
sriani

Rickard Andersson²⁰6-May-02 0:28

Rickard Andersson²⁰

6-May-02 0:28

You've heard what I said! Smile | :)

------------------------------------
Rickard Andersson, Suza Computing
ICQ#: 50302279
I'm from the winter country SWEDEN!

------------------------------------

code-behind in ASP.NET

Mazdak5-May-02 5:00

Mazdak

5-May-02 5:00

What is the advantage of using code-behind? hen should I use it and when should I use aspx ?

thanks

Mazy

"The path you tread is narrow and the drop is shear and very high,
The ravens all are watching from a vantage point near by,
Apprehension creeping like a choo-train uo your spine,
Will the tightrope reach the end;will the final cuplet rhyme?"Cymbaline-Pink Floyd

Re: code-behind in ASP.NET

Not Active5-May-02 5:12

Re: code-behind in ASP.NET

5-May-02 5:12

Code behind allows you to seperate presentation from code. i.e. you don't need to embed asp script with html code. You can also share a code-behind module between pages. If you develop a common rountine it can used by all your pages.

Mazdak5-May-02 6:55

Mazdak

5-May-02 6:55

Thank you Mark Smile | :)

Mazy

"The path you tread is narrow and the drop is shear and very high,
The ravens all are watching from a vantage point near by,
Apprehension creeping like a choo-train uo your spine,
Will the tightrope reach the end;will the final cuplet rhyme?"Cymbaline-Pink Floyd

Deploying ASP.NET project

Not Active5-May-02 3:32

Re: Deploying ASP.NET project

5-May-02 3:32

Anyone run into this problem?

I built a C# web app and then FTP'd it, after building in release, to a hosting server. When I try accessing the page I get an error. "Could not load type namespace.page".

Microsoft Technet says the problem is that C# Web Apps must be built if they contain code-behind modules. I checked again to make sure it was built. Still no luck. Since the article also said it occurs with C# and not VB.NET I created a simple VB.NET webapp and copied it to the deployment server. Same error.

Not Active6-May-02 2:10

I just want to greet the world... Where do I start?

6-May-02 2:10

Found the problem. There was no aspnet_client folder in the web root.

DeadWisdom3-May-02 18:48

DeadWisdom

3-May-02 18:48

I just want to make an "Hello World" for ASP.Net. A simple file that displays to the user "Hello World" in C#... With no overhead. In ASP regular, it was easy... I just did <% Response.Write "Hello World" %>

What do I do in aspx??? I don't even know, exactly, how to tell it that I want to use C#. This is a bit overwhelming.

Re: I just want to greet the world... Where do I start?

James T. Johnson3-May-02 19:03

Re: I just want to greet the world... Where do I start?

3-May-02 19:03

<%@ Page language="c#" runat="server" %>
<script runat="server" language="c#">
 void Page_Load()
 {
  labelHi.Text = "Hello World";
 }
</script>
 
<html>
<head><title>Hello</title></head>
 
<body>
 <asp:label id="labelHi" runat="server" />
</body>
</html>

That should do the trick Smile | :)

HTH,

James

Simplicity Rules!

DeadWisdom3-May-02 20:55

DeadWisdom

3-May-02 20:55

Wait... This is how you do it? Forgive me, but that seems like a hack. Isn't there a simple way to do it? I'm looking for "response.write('hello world');"... Does everything have to be done with a control?

Re: I just want to greet the world... Where do I start?

James T. Johnson3-May-02 20:59

Re: I just want to greet the world... Where do I start?

3-May-02 20:59

It doesn't have to be, but that is the "ASP.NET way" of doing things.

If you want to use Response.Write just throw in a script block in the body block doing so Smile | :)

James

Simplicity Rules!

Not Active5-May-02 5:17