[AccessD] Maximum number of columns in a table ?

Francisco H Tapia my.lists at verizon.net
Fri Feb 7 11:13:00 CST 2003


I dunno most Access DBA's usually do a minimum of 3 peoples work... for some
reason it seems to traditionally move this way, it's probably due to the
fact that Access has become such a memory, network traffic, and HDD
footprint HOG, that as developers we're forced to deal with many issues that
other developers don't.  Either that or it's just me, and my fascination w/
computers ;o).

In the end "You must DO what the boss wants".  That doesn't mean you have to
sacrifice the data model or your principles.  Remember exactly what they've
asked you... they probably asked, "we need more fields on this form to input
more data".  That is not the same as more fields in your table.  Being in
the habit of maintaining my own apps, I want to always improve both my work
style and development cycle to make maintenance a breeze.  Of those things
I've learned that the right way usually takes longer to develop, but is
frequently much much easier to maintain.  Adding additional "virtual" fields
to screens and tables is a breeze when the system is developed correctly.
In your case it seems that what you are after is a junction table w/ a temp
table.  The junction table will store all the data you need, month 1,2,3,
etc... but the temp table would fill in the blanks.  Such that  If data is
entered for Quote MS, for months 1, 3, 7... then that data would be stored
in the junction table to something that resembled this:

PKID
QuoteID
DateID <--represents a number 1-12 or whatever your breakdown is.
Value

the temp table would auto-generate all the missing dates/months buy
comparing with a base table that  that includes all these months something
similar to the following setup..

PKID
DateID

Buy running an unmatched INSERT query you can quickly add fields to a temp
table w/ all the real data and the virtual fields for binding to the form or
report.  Are these a lot of steps? YES, are they worth it?, YES.  You are
saving space in your database by not storing the additional fields that you
don't need, but at the same time now have the flexibility to add additional
fields by simply visiting your MonthBase table so you can add Months from
0 - Infinity.

HTHs,
-Francisco
http://rcm.netfirms.com
----- Original Message -----
From: <Oleg_123 at xuppa.com>
To: <accessd at databaseadvisors.com>
Sent: Friday, February 07, 2003 6:57 AM
Subject: RE: [AccessD] Maximum number of columns in a table ?


: hi Charles,
:
: hmm.. both acees, and excel, + vba knowledge, sql, powerpoint (haven't
: done anything on it, and am not really dying to). Most of the time I just
: do reports using their own applications, and applications they've
: livensed. Plus some minor financial analysis; talking to traders, etc.
: Well, its' NY, one person does 3 people's work :)
: in I don't usually develop applications, ony various forms to do
: reports,send mail, export data to excel and reports there, get data from
: parodox and other sources, etc
: There's no maintanance here since i am not part of it/development/system
: group. Same was the case at my last job. I don't know whether I'll be here
: in 6 months, dunno about Texas, but in NY unfortunately nothing is
: certain.
:
: > Oleg,
: >
: > Did they hire you to develop databases or to develop spreadsheets?  If
: > you plan on being there six months from now when maintenance will be
: > required, then do it the right way.  If you want to get a reputation for
: > developing bad applications, then do it the way you boss says.
: >
: > Charles Wortz
: > Software Development Division
: > Texas Education Agency
: > 1701 N. Congress Ave
: > Austin, TX 78701-1494
: > 512-463-9493
: > CWortz at tea.state.tx.us
: > (SELECT * FROM users WHERE clue > 0)
: >
: >
: > -----Original Message-----
: > From: Oleg_123 at xuppa.com [mailto:Oleg_123 at xuppa.com]
: > Sent: Thursday 2003 Feb 06 13:44
: > To: accessd at databaseadvisors.com
: > Subject: RE: [AccessD] Maximum number of columns in a table ?
: >
: > Charles,  I ofcourse agree with Fransisco, and Jeff Putnam who wrote the
: > article. But that's how they want this, i was just checking if 70
: > columns may caz problems, frankly I've never seen a table like that. I
: > am not running the company and I ca't really input my rules. Right now
: > they've decided to refernish the division I personally would first paint
: > the walls, then do the carpeting, then bring the new furniture. They are
: > doing this in exactly the opposite order, some of the new furniture is
: > already here, and painting doesn't start till monday, and we'll still
: > have to wear corparate attire. And we can't really argue.. :)
: >
: >
: >> Oleg,
: >>
: >> If you want to be a spreadsheet developer and not a database
: >> developer, then continue with your spreadsheet thinking.  But if you
: >> do want to be a database developer, please follow Francisco's advice.
: >>
: >> Charles Wortz
: >> Software Development Division
: >> Texas Education Agency
: >> 1701 N. Congress Ave
: >> Austin, TX 78701-1494
: >> 512-463-9493
: >> CWortz at tea.state.tx.us
: >> (SELECT * FROM users WHERE clue > 0)
: >>
: >>
: >> -----Original Message-----
: >> From: Oleg_123 at xuppa.com [mailto:Oleg_123 at xuppa.com]
: >> Sent: Thursday 2003 Feb 06 13:11
: >> To: accessd at databaseadvisors.com
: >> Subject: Re: [AccessD] Maximum number of columns in a table ?
: >> Importance: Low
: >>
: >>
: >> Francisco,
: >>
: >> right now we have column fields 2m(onths) 3, 4-6, 7-12, >2y (years
: >> which is 13 - 24) and <2y (goes up to 30 years)) Now they want a field
: >
: >> for each individual monts; I think that creating a table with roughtly
: >
: >> 70 fields would be the most painless solution (and from it a query
: >> with original fields - 4-6, 7-12, and reling it as datasource for
: >> reports)
: >>
: >>> Oleg,
: >>>    70 fields? I recommend reviewing the benefits of normalization,
: >>> specifically BCNF which is a derived from 3NF
: >>> http://databasejournal.com/sqletc/article.php/1443021
: >>>
: >>> more hits on google:
: >>> http://tinyurl.com/5g4v
: >>>
: >>> -Francisco
: >>> http://rcm.netfirms.com
: >>> ----- Original Message -----
: >>> From: "Drew Wutka" <DWUTKA at marlow.com>
: >>> To: <accessd at databaseadvisors.com>
: >>> Sent: Wednesday, February 05, 2003 3:47 PM
: >>> Subject: RE: [AccessD] Maximum number of columns in a table ?
: >>>
: >>>
: >>> : I believe the number of fields in a table is 255....I am assuming
: >>> it's the : same for a query.
: >>> :
: >>> : Drew
: >>> :
: >>> : -----Original Message-----
: >>> : From: Oleg_123 at xuppa.com [mailto:Oleg_123 at xuppa.com]
: >>> : Sent: Wednesday, February 05, 2003 1:44 PM
: >>> : To: accessd at databaseadvisors.com
: >>> : Subject: [AccessD] Maximum number of columns in a table ?
: >>> :
: >>> :
: >>> : I need to feet around 70, can I ? I found this on google, but
: >>> somehowi
: >>> : don't trust it; o limit on rows ??
: >>> : ------------------------------------
: >>> :
: >>> : Maximum number of rows per table No Limit
: >>> :
: >>> : Maximum number of tables per database No limit
: >>> :
: >>> : Maximum number of tablespaces per database 32767
: >>> :
: >>> : Maximum number of devices 32767
: >>> :
: >>> : Maximum storage capacity 70 TB
: >>> :
: >>> : Maximum row size (excluding BLOB & FO columns) 3992 bytes
: >>> :
: >>> : Maximum number of columns per table 252
: >>> :
: >>> : Maximum number of columns per index 16
: >>> :
: >>> : Maximum number of journal files per database 8
: >>> :
: >>> : Maximum length of table/column name 18 bytes
: >>> :
: >>> : Maximum number of tables per join 31
: >>> :
: >>> : Maximum number of savepoints per transaction 32
: >>> :
: >>> : Maximum cache memory 2GB





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