[AccessD] Why 255?

DWUTKA at marlow.com DWUTKA at marlow.com
Wed Oct 19 12:22:55 CDT 2005


And just for an example Lonnie, the size limit of a text field.  It's 255.
When Jet actually writes the data for a text field, it writes the first byte
to represent the size of that field.  For example, if you had a table like
this:

Field1:
Happy
Smiles
A
<empty>
Howdy, how are you?

Inside the .mdb file itself, you would have this information: (I will use
Asc(*) to represent a byte with the value represented by the asterick)

<some stuff>Asc(5)Happy<some stuff>Asc(6)Smiles<some stuff>Asc(1)A<some
stuff>Asc(0)<some stuff>Asc(19)Howdy, how are you?<some stuff>

That way, when Jet is reading the table, it reads the first byte, then it
reads that number of following bytes to retrieve the data for that
particular field.

Thus the limit of 255 characters in a text field.

Drew

 

-----Original Message-----
From: Lonnie Johnson [mailto:prodevmg at yahoo.com]
Sent: Tuesday, October 18, 2005 12:44 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Why 255?


I knew that was some cool geek explanation. I love this stuff.

Gary Kjos <garykjos at gmail.com> wrote:Hi Lonnie,

Hexidecimal FF = 255. Or actually binary 11111111 = 255 it's the
largest number you can express in a single byte

GK

On 10/18/05, Lonnie Johnson 
wrote:
> I know this is going to be an easy one for most of you? I am a developer
but I don't know this. Why does Access have some limits of 255 for a lot of
things such as number of fields in a table, number of concurrent users and
so forth?
>
> Just curious.
>
>
>
> May God bless you beyond your imagination!
> Lonnie Johnson
> ProDev, Professional Development of MS Access Databases
> Visit me at ==> http://www.prodev.us
>
>
>
>
>
>
>
>
>
>
>
>
> ---------------------------------
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--
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May God bless you beyond your imagination!
Lonnie Johnson
ProDev, Professional Development of MS Access Databases
Visit me at ==> http://www.prodev.us





 





		
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