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How do Applications generate values for the primary keys in database tables? I know that setting the type as AutoNumber (setting Identity Specification to 'Yes' as in MS-SQL Server) will generate incremented values each time rows are inserted. Keeping in mind that deleted rows' values will never be reused the values will soon become too large for a .NET variable like 'long' to hold it after several updations. I guess this may result in exceptions. And the application to go wrong in future. How is it handled in an application like Yahoo or just this forum 'CodeProject' where the posts come in large numbers (each post requiring a unique ID) daily. Thank you.
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tonymathewt wrote: the values will soon become too large for a .NET variable like 'long' to hold it after several updations.
Just how many records do you think you're going to put into a table?? You do realize that the Long type in VB.NET is a 64-bit signed value and has a max value of 9,223,372,036,854,775,807?? That's 9.2 million trillion id's...
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But Dave, in case of yahoo mail/orkut all the mails/scraps will be stored in a single table(not sure). Then it would have long crossed this number even if we delete the mails the auto number wont go back, it will only keep incrementing.
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tonymathewt wrote: in case of yahoo mail/orkut all the mails/scraps will be stored in a single table(not sure).
Maybe. Even so, I'd be willing to bet they haven't handled that many emails, nor do they store them away like this. Remember, I said over 9,000,000,000,000,000,000 ID's. I'd be surprised if the Internet has carried that many emails in the last 10 years combined.
tonymathewt wrote: Then it would have long crossed this number even if we delete the mails the auto number wont go back, it will only keep incrementing.
Yep. Then it just rolls over and starts back at 0 again. The other option is a composite key, where two or more columns cooperate the generate a unqiue key, like userId and an incremented value.
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What would be the minimal size of a database that has the maximal number of records with just the id in it?
Are there enough hard disks around on earth?
(I'm to tired to calc it out )
-^-^-^-^-^-
no risk no funk
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Urs, let the database grow to any size but will the application be able to handle the key(probably autonumber) that has grown to an enormous size?
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I was just joking a bit.
I think there are only very few applications that have to deal with numbers of records that come close to the maximum number of possible keys.
A simple solution can then be that you create a composite primary key consisting of to columns of type long. Imaging the number of possible keys now.
-^-^-^-^-^-
no risk no funk
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Thank you Urs
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Dave Kreskowiak wrote: 9,000,000,000,000,000,000
I wonder about the storage and the data type for this number.
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A 64-bit number goes a long way...
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Hi..
I have the MCP certificate in developing asp.net using visual C#.In my university I studied the Java as an object oriented language only(without learning how to make business project that could be needed by a company).I have a desire to learn USB port programming and mobile programming.
May you learn me how to find trusted training centers for each of the fields I mentioned above so I can reach the second level in these fields.
I am too late but i will never give up
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I don't think training centers are good, at least with respect to Chennai, India. Self-learning kits and practice alone is good.
I came across one training center who is offering AJAX, PHP as training courses. Some center like Intelliblitz in Madipakkam, Chennai does that.
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Hi..
For Microsoft courses I heard that there is a way to find trusted training centers through the Microsoft website but I dont know how.
But other fields(advanced java(to build projects),USB programming) I realy dont know any idea about how to find trusted training centers for them.
I am too late but i will never give up
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Hi..
Thank you for leading me for these pages which I were searching for.
About java training centers in Saudi Arabia I found this comment:
This country is served by the United Arab Emirates registration office and regional Middle East Web Site
Does this mean there is no trusted training centers for java in Saudi Arabia or something else?
you can check this in the page:
http://www.sun.com/training/world_training.html#SA[^]
Also I still don't have any idea about finding training centers for USB,COM ports programming Which are usefull for developing GPS devices and such things.Do you have any idea about it?.
I am too late but i will never give up
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TheEagle wrote: I still don't have any idea about finding training centers for USB,COM ports programming
And, for the last time, you won't find any! Noone offers programming classes specifically on USB or COM ports, or how to use them. This is stuff you're only going to find in books, but only in passing. You won't find books specifically on talking to USB devices or COM ports.
This is where the skill of "doing your own research" comes in handy. Non programmer can survive in this business without it.
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Hi,
I've a J++ component registered in COM+. When I try to create an object of that class, I'm getting an exception "Error: 429 - ActiveX component can't create object". I refered all the relevant information available in net but nothing works for me.
I've set the classpath variable. I've all the java libraries in c:\windows\java\** folder.
Can someone help me in identifying and fixing this issue?
VijayRaghavan J
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Ever get this to work?
"I guess it's what separates the professionals from the drag and drop, girly wirly, namby pamby, wishy washy, can't code for crap types." - Pete O'Hanlon
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Hi All,
starting up a software development dept at our company,any concepts i should have in mind?
Any help me out with what i should include in the concept paper.
cheers
The nature of your experience depends on your point of view.
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As far as structure goes, it varies from shop to shop. Do you have a structure in place, now?
"I guess it's what separates the professionals from the drag and drop, girly wirly, namby pamby, wishy washy, can't code for crap types." - Pete O'Hanlon
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This is my profile and want some advise..
I am a student of Arts (B.A) did it from Correspondence due to some problem.. However at XII (SSC) I had major at Mathematics.
However I had interest into Computers and did Software Engineering...However at that time I did not get into Software Development.. Since I was not feeling that B.A was enough. I did MCA ( Master of Computer Application).. At the same time I did a course in Networking and Hardware..and entered a Job of Networking .. I currently into a web hosting company provides Technical Support..
My Interest are into Network Security and have already cleared EC-CEH certification
But I am unable to land into a decent job and finding it very difficult...Bcoz companies prefer B.E/B.Tech Student So I am feeling like moving to Software Development.. I just don't know where should I head to...
1.)Move into Software Development
2.)Try doing more certifications like CCNA, CCSP , CCSA and CISSP..
3.)Any of your **Ideas
regards
Vinod
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if you've got a nonconventional background and limited work experience you'd be better of trying to get a job at a small company that makes its hiring decisions based off of technical interviews only rather than a large one that's HR will probably discard your resume as unsuitable based on an automated system.
--
You have to explain to them [VB coders] what you mean by "typed". their first response is likely to be something like, "Of course my code is typed. Do you think i magically project it onto the screen with the power of my mind?" --- John Simmons / outlaw programmer
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dan neely wrote: that's HR will probably discard your resume as unsuitable based on an automated system.
Absolutely true.
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how to create master detail for ADD/EDIT/Delete/Display
master data
(company code , name, mapcode)
- text box
detail data
( company detail code, fin_statdate, fin_enddate, process_status, companycode)
--grid view
vijaya
vijaya
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