Re: external table - Mailing list pgsql-novice

On 07/04/2014 02:47 AM, Albe Laurenz wrote:
> John R. Sowden wrote:
>> I am currently writing my own database apps in foxpro/dos (since 1980).
>>    pg seems to be a good way to move on, but I see a couple of problems.
>>
>> All of the application programs seem to be c based.  Learning c for
>> business apps is a problem.
>
> Why do you have to learn C to use a program that is written in C?
> Or do I misunderstand you?
>
>> Currently I use a lookup database for many kinds of applications that I
>> create for my company.  It seems that the sql database arrangement is to
>> have 1 database with multiple related tables inside.  I do not want to
>> have to keep current multiple look-up tables (cities, counties, police
>> depts, their phone numbers, etc.) in separate databases.  Can I use, say
>> a database with billing tables (transacions, etc.) and refer to an
>> external lookup table?  I might store a "G" in the city field, which
>> would refer to "San Francisco", etc.
>
> What is the problem with keeping the lookup table in the database?
>
> There is a foreign data wrapper (file_fdw) included with PostgreSQL
> as a "contrib module" that will allow to use a flat OS file like a table.
> If you modify the file while PostgreSQL uses it, bad things are likely to happen.
> If the file doesn't change, I would definitely COPY it into a table.
>
> Yours,
> Laurenz Albe
>
I write programs using the foxpro/dos language (I run them using
ubuntu/dosemu).  It seems that the languages that I must write my
database applications in, using pg apis, are c based.  In reading books
on the issue, the quote that stands out in the first few pages is "if
you understand c, then you won't have any problem learning ..."  I bout
the kernigan 7 ritchie book in the 80s and decided that that is
ridiculous, unless I wanted to get a job writing software.

My programs are not just a list of queries and input forms.  One is an
accounting program (GL) another is an AR/billing program, etc.

re: the external lookup table, I assume that I will more all of my dbf
data to pg, not maintain a foreign table (foreign to pg). I am wondering
how to create queries, etc. relating a table that is not inside the
connected database.  I expect to have separate databases for gl,
billing, dispatch, service call tracking.  Now each of these are
separate tables (.dbf files).  These are not flat files, they are
relational.

John