Thread: Some questions about oid's and sequences.
Howdy: I am coming from the Windows world, and Microsoft SQL variants in particular. Both Access and SQL Server have autoincrement data types -- I understand that Postgresql has "sequences" which do the same thing, but I can't find any documentation on them. I have browsed all the online documentation that comes with Postgresql, and can't find anything about it. Could someone point me to some docs that would explain how to use sequences? I have a similar question about oid's. I am not sure what they are -- from their name, I would guess that they are autoassigned, unique identifiers for each row in a table. Is that correct? If so (or even if not), how do I create and use them. Any documentation that addresses oid usage specifically? I am confused because oid's seem to be to substitute for the BLOB data type which is available in other RDBMS's. If you post a reply to this, could you also cc: to enorvelle1@uswest.net. TKA for your assistance. -Erik Norvelle
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Hello Erik,
mercoledì, 2 settembre 98, you wrote:
EN> Howdy:
EN> I am coming from the Windows world, and Microsoft SQL variants in
EN> particular. Both Access and SQL Server have autoincrement data types --
EN> I understand that Postgresql has "sequences" which do the same thing,
EN> but I can't find any documentation on them. I have browsed all the
EN> online documentation that comes with Postgresql, and can't find anything
EN> about it. Could someone point me to some docs that would explain how to
EN> use sequences?
if U have v6.4 then:
CREATE TABLE tbl(fld SERIAL);
if you have v6.3.2 then:
CREATE SEQUENCE serial;
CREATE TABLE distributors (
did DECIMAL(03) PRIMARY KEY DEFAULT NEXTVAL('serial')
);
EN> I have a similar question about oid's. I am not sure what they are --
EN> from their name, I would guess that they are autoassigned, unique
EN> identifiers for each row in a table. Is that correct?
Yes. OIDs are uniq to the whole database not only for tables.
EN> If so (or even
EN> if not), how do I create and use them. Any documentation that addresses
EN> oid usage specifically? I am confused because oid's seem to be to
EN> substitute for the BLOB data type which is available in other RDBMS's.
EN> If you post a reply to this, could you also cc: to
EN> enorvelle1@uswest.net. TKA for your assistance.
EN> -Erik Norvelle
Best regards,
Jose' mailto:sferac@bo.nettuno.it
> Howdy: > > I am coming from the Windows world, and Microsoft SQL variants in > particular. Both Access and SQL Server have autoincrement data types -- > I understand that Postgresql has "sequences" which do the same thing, > but I can't find any documentation on them. I have browsed all the > online documentation that comes with Postgresql, and can't find anything > about it. Could someone point me to some docs that would explain how to > use sequences? > man create_sequence > I have a similar question about oid's. I am not sure what they are -- > from their name, I would guess that they are autoassigned, unique > identifiers for each row in a table. Yes. oid stands for Object I.D. Remember postgress is documented in an object oriented way. The tables definitions is called the "class" from which the "objects" (records) are instantiated. > Is that correct? If so (or even > if not), how do I create and use them. They are created automatically. To access them type: select oid from blah; > Any documentation that addresses > oid usage specifically? don't know. I kind of picked up the info from the list. > I am confused because oid's seem to be to > substitute for the BLOB data type which is available in other RDBMS's. No they are not even close to the same thing. Hope this helps...james