Onno-
Yes, they will slow down performance from the perspective that including them in the table definition means they will automatically be inherited in any query or form you build on the table. They are also bad from the perspective of hiding the actual relationship to the lookup table and the underlying values. For a detailed discussion, see "Problem With Lookups.doc" in the Articles_Excerpts folder of the Files section on the group website.
Having said that, combo boxes can be very useful on data entry forms, and they won't have a big impact on performance unless the Row Source returns more than 1,000 rows. You should judiciously add combo boxes on forms as you design them. If you use a Wizard to build your form, you can always go into Design View, right click the text box built by the Wizard, and choose Change To / Combo Box to convert the control. Then add the Row Source, Bound Column, Column Count, and Column Widths properties as needed.
John Viescas, Author
Microsoft Access 2010 Inside Out
Microsoft Access 2007 Inside Out
Microsoft Access 2003 Inside Out
Building Microsoft Access Applications
SQL Queries for Mere Mortals
(Paris, France)
On Aug 14, 2014, at 11:18 AM, 'Knol, Onno' onno.knol@pbl.nl [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:
Dear pro's and other readers,
My attention was drawn to the subject header (Table Lookup Alternative)
But My question appears to be different.
The Question is: does the use of combo boxes with lookups to related tables, in a table definition, slow down the performance?
Should one avoid that and only use those combo boxes in forms as necessary?
The drawback is that also in queries ( both in the forms data sources and in other queries) you have to create more relations by hand.
What would be your advice ?
Thanks for your input,
Onno Knol
The Netherlands
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Posted by: John Viescas <johnv@msn.com>
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