[AccessD] Question about the TableDef.Fields collection

[Susan Harkins]

And you can always use an index to avoid duplicate input values on the
Country field. 

Susan H. 


Autonumbers serve another purpose, speeding up joins.  Joining strings
between tables requires a visit to a library where the string is scanned and
compared to the other field byte by byte.  A long integer OTOH used a simple
equal operator on a 32 bit number.  One instruction vs potentially hundreds.

On Fri, Aug 26, 2022 at 9:46 AM Arthur Fuller <fuller.artful at gmail.com>
wrote:

> Like most Access programmers, I use AutoNumber fields as Primary Keys 
> whenever it makes sense. However, it doesn't always make sense, and 
> this is particularly so when the table of interest contains a 
> relatively small number of rows. The reason I say this is because 
> using an AutoNumber as the PK demands additional logic, to prevent 
> otherwise equal rows from being added. For example, in a table of 
> Countries, using an AutoNumber as the PK does not prevent the addition 
> of country names that would duplicate an existing row. You could add 
> Israel a dozen times, with each row having an AutoNumber. That said, I 
> can think of no reason to have an AutoNumber in a table unless it is the
PK.
>
> But in tables containing no AutoNumber field, is there a Field 
> attribute that identifies the PK of the table of interest?
>
> Thanks in advance.
>
> --
> Arthur
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John W. Colby
Colby Consulting
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