SQL-Query 2 get primary key

You may query pg_indexes as in:

select * from pg_indexes where tablename = 'test';

tablename|indexname|indexdef
---------+---------+-----------------------------------------------------------------------

test |test_pkey|CREATE UNIQUE INDEX "test_pkey" ON "test" USING btree
("id" "int4_ops")
(1 row)

Marc Grimme ha scritto:

Hi,

if I create a table like this:
CREATE TABLE test (
id decimal(3) primary key,
name varchar(32));

how can I ask postgres which is the primary key from table test?
I hope to get something like "id is the primary key from table test.".
Any ideas
Marc
--
-----------------------------------------------------------
Marc Grimme - An der Muehle 1 - 85716 Unterschleissheim
Fon: +49 89 37 48 81 22 - +49 89 37 48 92 7 - 3/0 -
mail2: grimme@informatik.tu-muenchen.de, grimme@atix.de
-----------------------------------------------------------
The UNIX Guru's View of Sex:
# unzip ; strip ; touch ; finger ; mount ; fsck ; more ; yes ; umount ;
sleep

--
- Jose' -

And behold, I tell you these things that ye may learn wisdom; that ye may
learn that when ye are in the service of your fellow beings ye are only
in the service of your God. - Mosiah 2:17 -

Hi,

jose' soares wrote:

You may query pg_indexes as in:

select * from pg_indexes where tablename = 'test';

tablename|indexname|indexdef
---------+---------+-----------------------------------------------------------------------

test |test_pkey|CREATE UNIQUE INDEX "test_pkey" ON "test" USING
btree ("id" "int4_ops")
(1 row)

I read about the pg_indexes table and stuff but I am interested in the
"columnname" of the primary key in the specified table.
Isn�t this feature very important?
Cheers,
Marc
--
-----------------------------------------------------------
Marc Grimme - An der Muehle 1 - 85716 Unterschleissheim
Fon: +49 89 37 48 81 22 - +49 89 37 48 92 7 - 3/0 -
mail2: grimme@informatik.tu-muenchen.de, grimme@atix.de
-----------------------------------------------------------
The UNIX Guru's View of Sex:
# unzip ; strip ; touch ; finger ; mount ; fsck ; more ; yes ; umount ;
sleep

Thus spake Marc Grimme

if I create a table like this:
CREATE TABLE test (
id decimal(3) primary key,
name varchar(32));

how can I ask postgres which is the primary key from table test?

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';

That lists all the primary keys in your database. Add a "WHERE pg_class
= 'test'" clause to get the specific table.

Note that this makes the assumption that only one field can be in the
primary key (no complex primary keys) but I don't think there will
ever be more than one the way we declare it now.

-- 
D'Arcy J.M. Cain <darcy@{druid|vex}.net>   |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 424 2871     (DoD#0082)    (eNTP)   |  what's for dinner.

"D'Arcy J.M. Cain" wrote:

Thus spake Marc Grimme

if I create a table like this:
CREATE TABLE test (
id decimal(3) primary key,
name varchar(32));

how can I ask postgres which is the primary key from table test?

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';

Should it work in 6.4.0 ?

It gives an empty table for me ;(

That lists all the primary keys in your database. Add a "WHERE pg_class
= 'test'" clause to get the specific table.

You probably mean "pg_class.relname = 'test'" ?

Note that this makes the assumption that only one field can be in the
primary key (no complex primary keys) but I don't think there will
ever be more than one the way we declare it now.

Actually you can declare multi_field PK as
(Bruce: this probably should be added to \h create table):

hannu=> create table test(
hannu-> id1 int,
hannu-> id2 int,
hannu-> meat text,
hannu-> primary key (id1,id2)
hannu-> );
NOTICE: CREATE TABLE/PRIMARY KEY will create implicit index test_pkey
for table test
CREATE

-------------------------
Hannu

if I create a table like this:
CREATE TABLE test (
id decimal(3) primary key,
name varchar(32));

<snip>

Note that this makes the assumption that only one field can be in the
primary key (no complex primary keys) but I don't think there will
ever be more than one the way we declare it now.

fyi, the following syntax is allowed:

CREATE TABLE test (
id decimal(3),
name varchar(32),
primary key(id));

and multiple columns can be declared as primary keys.

- Tom