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Don't understand the relationship between a combo box and a table



 
 
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  #11  
Old March 31st, 2010, 05:30 AM posted to microsoft.public.access.gettingstarted
Richard
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Posts: 1,419
Default Don't understand the relationship between a combo box and a ta

"forest8" wrote:

What do you mean by "simple, properly normalized tables"?


"John W. Vinson" wrote:


How about:

Students
StudentID primary key
LastName
FirstName
other biographical info as appropriate
SchoolID where is this student enrolled

Cases
CaseNo primary key
StudentID link to Students, who is being investigated
other fields relevant to the case as a whole

Categories
CatgoryID primary key
Category (e.g. School, Community, ...)

Issues
IssueID primary key
Description text, e.g. "lack of role models"
CategoryID in which category is this issue

StudentIssues
CaseNo link to Cases and thence to Students
IssueID link to Issues, which issue did this student raise


This is the primer for a normalized table, take the MVP's advice. If your
table aren't right nothing else matters.

Richard
  #12  
Old March 31st, 2010, 05:38 AM posted to microsoft.public.access.gettingstarted
forest8
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Posts: 196
Default Don't understand the relationship between a combo box and a ta

Thank for the advice. I'm taking your suggestions into my database.

If I run into any issues, I'll start a new thread.

Thanks again.

"John W. Vinson" wrote:

On Tue, 30 Mar 2010 15:54:02 -0700, forest8
wrote:

Hi there

Currently I am getting the following message:

"The operation failed. There are too many indexes on table 'Orders'. Delete
some of the indexes on the table and try the operation again."

In my table, I am trying to change a text box into a multi=select combo box.

There are 45 fields in my table of which 40 have this multi-select combo box.

I don't understand where these indexes are being created.

I do have 1 primary key in my table.

Thank you


My guess is that these combo boxes have indexes of their own which contribute
toward the form's index count.

I would *VERY STRONGLY* suggest that putting combo boxes into a table -
particularly multiselect combo boxes - is a major misuse of Access, and that
it is unnecessary!

Table datasheets are becoming more complex with recent releases of Access, but
they're still *very limited*. There is nothing that you can do with a
complicated table that you cannot do with simple, properly normalized tables,
and a well designed Form. You do NOT need multiselect combos, or any combos at
all, in your Table in order to do so.
--

John W. Vinson [MVP]
.

  #13  
Old March 31st, 2010, 06:22 AM posted to microsoft.public.access.gettingstarted
John W. Vinson
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Posts: 18,261
Default Don't understand the relationship between a combo box and a ta

On Tue, 30 Mar 2010 20:41:02 -0700, forest8
wrote:

Currently it's one field per issue.


So... when you add a new issue you need to redesign your table, change all
your queries, restructure all your forms, all your reports?

Sorry, but that design is *just plain wrong*, and is the source of your
difficulties with indexing and with form design. You're using a relational
database - use it relationally! Tables should be tall and thin, not wide and
flat; data should be stored in fields, not in fieldnames.

--

John W. Vinson [MVP]
  #14  
Old March 31st, 2010, 06:22 AM posted to microsoft.public.access.gettingstarted
John W. Vinson
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Posts: 18,261
Default Don't understand the relationship between a combo box and a ta

On Tue, 30 Mar 2010 19:52:01 -0700, forest8
wrote:

What do you mean by "simple, properly normalized tables"?


What I said elsewhere in the thread:

How about:

Students
StudentID primary key
LastName
FirstName
other biographical info as appropriate
SchoolID where is this student enrolled

Cases
CaseNo primary key
StudentID link to Students, who is being investigated
other fields relevant to the case as a whole

Categories
CatgoryID primary key
Category (e.g. School, Community, ...)

Issues
IssueID primary key
Description text, e.g. "lack of role models"
CategoryID in which category is this issue

StudentIssues
CaseNo link to Cases and thence to Students
IssueID link to Issues, which issue did this student raise

Similar tables for Responses, not sure how you want them linked.

--

John W. Vinson [MVP]
  #15  
Old March 31st, 2010, 05:16 PM posted to microsoft.public.access.gettingstarted
Jeff Boyce
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Posts: 8,621
Default Don't understand the relationship between a combo box and a ta

OK, now try running the database documenter on the table(s). See how many
indices Access believes you have...

Regards

Jeff Boyce
Microsoft Access MVP

--
Disclaimer: This author may have received products and services mentioned
in this post. Mention and/or description of a product or service herein
does not constitute endorsement thereof.

Any code or pseudocode included in this post is offered "as is", with no
guarantee as to suitability.

You can thank the FTC of the USA for making this disclaimer
possible/necessary.

"forest8" wrote in message
...
When I check the indexes, there are only 2 indexes created:

One is the tables' primary key and the other is the Foreign Key.

I can't seem to see any other index.



"Jeff Boyce" wrote:

First, be aware that the general consensus among regular Access users is
that more than about 30 fields in a table is fairly unusual, and usually
indicates that the table/database needs a bit more normalizing.

Access adds indexes of it's own, "behind the curtain" so to speak. Have
you
opened the table in design view, clicked on the Indexes button and
inspected
what indices are showing?

Regards

Jeff Boyce
Microsoft Access MVP

--
Disclaimer: This author may have received products and services mentioned
in this post. Mention and/or description of a product or service herein
does not constitute endorsement thereof.

Any code or pseudocode included in this post is offered "as is", with no
guarantee as to suitability.

You can thank the FTC of the USA for making this disclaimer
possible/necessary.

"forest8" wrote in message
...
Hi there

Currently I am getting the following message:

"The operation failed. There are too many indexes on table 'Orders'.
Delete
some of the indexes on the table and try the operation again."

In my table, I am trying to change a text box into a multi=select combo
box.

There are 45 fields in my table of which 40 have this multi-select
combo
box.

I don't understand where these indexes are being created.

I do have 1 primary key in my table.

Thank you



.



  #16  
Old March 31st, 2010, 09:55 PM posted to microsoft.public.access.gettingstarted
John Spencer
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Posts: 7,815
Default Don't understand the relationship between a combo box and a ta

The indexes you don't see are hidden and will not show up when you use the
indexes dialog. They are being created to manage the relationships being set
up by all those comboboxes used by the lookup fields.

You can detect them by using VBA code to step through the indexes collection
for the table.

This will give you the count of indexes for a particular table. Enter it into
the VA+BA immediate window.
Currentdb().TableDefs("NameOfTable").Indexes.Count

John Spencer
Access MVP 2002-2005, 2007-2010
The Hilltop Institute
University of Maryland Baltimore County

forest8 wrote:
When I check the indexes, there are only 2 indexes created:

One is the tables' primary key and the other is the Foreign Key.

I can't seem to see any other index.



"Jeff Boyce" wrote:

First, be aware that the general consensus among regular Access users is
that more than about 30 fields in a table is fairly unusual, and usually
indicates that the table/database needs a bit more normalizing.

Access adds indexes of it's own, "behind the curtain" so to speak. Have you
opened the table in design view, clicked on the Indexes button and inspected
what indices are showing?

Regards

Jeff Boyce
Microsoft Access MVP

--
Disclaimer: This author may have received products and services mentioned
in this post. Mention and/or description of a product or service herein
does not constitute endorsement thereof.

Any code or pseudocode included in this post is offered "as is", with no
guarantee as to suitability.

You can thank the FTC of the USA for making this disclaimer
possible/necessary.

"forest8" wrote in message
...
Hi there

Currently I am getting the following message:

"The operation failed. There are too many indexes on table 'Orders'.
Delete
some of the indexes on the table and try the operation again."

In my table, I am trying to change a text box into a multi=select combo
box.

There are 45 fields in my table of which 40 have this multi-select combo
box.

I don't understand where these indexes are being created.

I do have 1 primary key in my table.

Thank you


.

 




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