What you seek is not possible, in any general sense.
The concept of "what is a database" varies too greatly between different DBMS
products, even if you restrict yourself to SQL DBMSs. Loosely the question is
like asking for a "list of websites".
If what you want is to have a product or service that is DBMS-agnostic, you need
to more precisely define the criteria for what you want a list of.
Here are some more specific definitions of a database:
- A DBMS process service endpoint or embedded library that you can connect to as
a client.
- A file or file collection on disk that is a logical database.
- A collection of database table variables that can be addressed within a common
database query.
- A collection of database table variables that can be collectively subject to a
common ACID transaction, changes to the collection succeed or no-op as a whole.
- A logical namespace for database table variables.
For some DBMS engines several of the above things are one and the same, while
with others they are not.
-- Darren Duncan
On 2018-11-15 6:09 PM, Daniel Kasak wrote:
Hi all.
I have a project that has to support pretty much every major database around,
plus a number of more esoteric "big data" platforms as well. Until now, I've had
a bunch of methods, implementing fetching databases, schemas, tables, etc, per
database, with database-specific queries ( eg against information_schema ).
Some of the newer databases I'm trying to support have very little
documentation, and in some cases no apparent way of fetching in the schema via
SQL. I've had a conversation with one of the tech support people for a DB
product who said that there were generic ODBC functions we can call for this
kind of thing. Is this the case?
I've done quite a bit of search, but can't find any docs that mention fetching
*databases* - either in ODBC docs or in Perl/DBI docs. The closest I've found
that *might* have worked was DBI's tables() method:
https://metacpan.org/pod/DBI#tables
... but:
- this doesn't work in cases where there is a separation between hierarchies at
the database level ( eg postgres only lists schemas and tables in the current
database )
- this isn't returning *anything* for me with any of the ODBC drivers I've tried
So is it possible to retrieve a list of databases in a generic way? Failing
that, assuming that there *is* some ODBC call ( as suggested by one DB vendor )
that I can use, is there some way of calling it from Perl with DBD::ODBC?
Thanks :)
Dan
