Thread: A few more JDBC meta-data questions...

Peter,

Thanks for your incisive replies to my earlier query.. I still have two questions.
(I wouldn't ask them if I was able to find the answers elsewhere, but I haven't
found them in the JDBC 1.2 or 2.0 specs, or the 2 books in my possession which
give some coverage to JDBC...)

>From JDBC,

1. Is it possible to programatically enumerate or discover the databases in a running database??

2. Is it possible to programmaticaly enumerate or discover the tables in a database??

For the latter, I believe that I could use regular queries against postgresq's system catalogs,
but I am primarily interested in portable approaches - generic SQL and JDBC which stand
a good chance of (eventually) working with other databases.

Thanks,
Mark Dzmura

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)))) This email routed via a wireless gateway!! ((((

Thus spake Mark Dzmura
> 1. Is it possible to programatically enumerate or discover the databases in a running database??
> 
> 2. Is it possible to programmaticaly enumerate or discover the tables in a database??

-- get list of databases                             
SELECT datname FROM pg_database;                        
-- get list of tables including views but not system tables
SELECT relname FROM pg_class   WHERE relkind = 'r' AND                                 relname !~ '^Inv' AND
relname!~ '^pg_';   
 
And for completeness;                                   
-- get list of attributes and types for a specific table
SELECT pg_attribute.attname, pg_type.typname   FROM pg_class, pg_attribute, pg_type   WHERE pg_class.relname =
'tablename'AND                pg_attribute.attnum > 0 AND       pg_attribute.attrelid = pg_class.oid AND
pg_attribute.atttypid= pg_type.oid;    
 
-- get list of tables and primary keys (assumes no complex keys)
-- only includes tables with primary keys so no views
SELECT pg_class.relname, pg_attribute.attname           FROM pg_class, pg_attribute, pg_index       WHERE pg_class.oid
=pg_attribute.attrelid AND       pg_class.oid = pg_index.indrelid AND       pg_index.indkey[0] = pg_attribute.attnum
AND      pg_index.indisprimary = 't';
 

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