Lists: | pgsql-docs |
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From: | Roman Smirnov <smirnov(at)dresearch(dot)de> |
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To: | PostgreSQL conferention <pgsql-docs(at)postgresql(dot)org> |
Subject: | SQL query: List all the databases in the server |
Date: | 2001-07-03 11:15:45 |
Message-ID: | 3B41A961.1070105@dresearch.de |
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Lists: | pgsql-docs |
Hi all!
I need SQL analog of \l command from psql.
Something like "list databases".
Does anyone can help me?
Beforehand thank,
Roman.
From: | Vince Vielhaber <vev(at)michvhf(dot)com> |
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To: | Roman Smirnov <smirnov(at)dresearch(dot)de> |
Cc: | PostgreSQL conferention <pgsql-docs(at)postgresql(dot)org> |
Subject: | Re: SQL query: List all the databases in the server |
Date: | 2001-07-03 11:44:19 |
Message-ID: | Pine.BSF.4.30.0107030740100.56876-100000@paprika.michvhf.com |
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Lists: | pgsql-docs |
On Tue, 3 Jul 2001, Roman Smirnov wrote:
> Hi all!
>
> I need SQL analog of \l command from psql.
> Something like "list databases".
If you just want a list of them you can get it from pg_database:
select datname from pg_database;
if you also want the username of the database owner you'll have to
cross pg_database.datdba to pg_user.usesysid something like this:
select d.datname,u.usename from pg_database d, pg_user u where d.datdba = u.usesysid;
Vince.
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From: | Tom Ivar Helbekkmo <tih(at)kpnQwest(dot)no> |
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To: | Vince Vielhaber <vev(at)michvhf(dot)com> |
Cc: | Roman Smirnov <smirnov(at)dresearch(dot)de>, PostgreSQL conferention <pgsql-docs(at)postgresql(dot)org> |
Subject: | Re: SQL query: List all the databases in the server |
Date: | 2001-07-03 12:35:28 |
Message-ID: | 86zoamdwbz.fsf@athene.i.eunet.no |
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Vince Vielhaber <vev(at)michvhf(dot)com> writes:
>> I need SQL analog of \l command from psql.
>> Something like "list databases".
>
> If you just want a list of them you can get it from pg_database:
>
> select datname from pg_database;
>
> if you also want the username of the database owner [...]
The psql program implements the various \-ed information commands
using SQL, and you can find the actual code by perusing its source
file "describe.c". In this case, we find that "\l" is:
SELECT pg_database.datname as "Database",
pg_user.usename as "Owner",
pg_encoding_to_char(pg_database.encoding) as "Encoding",
obj_description(pg_database.oid) as "Description"
FROM pg_database, pg_user
WHERE pg_database.datdba = pg_user.usesysid
UNION
SELECT pg_database.datname as "Database",
NULL as "Owner",
pg_encoding_to_char(pg_database.encoding) as "Encoding",
obj_description(pg_database.oid) as "Description"
FROM pg_database
WHERE pg_database.datdba NOT IN (SELECT usesysid FROM pg_user)
ORDER BY "Database";
However, the "Encoding" bits are only included if the system is
compiled with support for multiple character set encodings, and the
"Description" bits only if the command is given as "\l+", which is a
new one for me -- it's not included in "\?" output. It seems, from a
little experimentation, that that "+" suffix is available also for the
other "\" commands where it's relevant. Cool! :-)
The above SELECT is extensively reformatted from the strings it's
built from in the source file, of course.
-tih
--
The basic difference is this: hackers build things, crackers break them.
From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Tom Ivar Helbekkmo <tih(at)kpnQwest(dot)no> |
Cc: | Vince Vielhaber <vev(at)michvhf(dot)com>, Roman Smirnov <smirnov(at)dresearch(dot)de>, PostgreSQL conferention <pgsql-docs(at)postgresql(dot)org> |
Subject: | Re: SQL query: List all the databases in the server |
Date: | 2001-07-03 14:45:49 |
Message-ID: | 18380.994171549@sss.pgh.pa.us |
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Tom Ivar Helbekkmo <tih(at)kpnQwest(dot)no> writes:
> The above SELECT is extensively reformatted from the strings it's
> built from in the source file, of course.
An even easier way to see what queries psql emits for its backslash
commands is to start psql with -E option, then do the backslash
commands. This gives me, for example,
regression=# \l
********* QUERY **********
SELECT pg_database.datname as "Database",
pg_user.usename as "Owner"FROM pg_database, pg_user
WHERE pg_database.datdba = pg_user.usesysid
UNION
SELECT pg_database.datname as "Database",
NULL as "Owner"FROM pg_database
WHERE pg_database.datdba NOT IN (SELECT usesysid FROM pg_user)
ORDER BY "Database"
**************************
List of databases
Database | Owner
------------+----------
regression | postgres
template0 | postgres
template1 | postgres
(3 rows)
regression=#
regards, tom lane
From: | Roman Smirnov <smirnov(at)dresearch(dot)de> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Tom Ivar Helbekkmo <tih(at)kpnQwest(dot)no>, Vince Vielhaber <vev(at)michvhf(dot)com>, PostgreSQL conferention <pgsql-docs(at)postgresql(dot)org> |
Subject: | Re: SQL query: List all the databases in the server |
Date: | 2001-07-03 15:33:03 |
Message-ID: | 3B41E5AF.3050904@dresearch.de |
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Thanks to all!
Your help was very usefull
Thanks again,
Roman