Hello can any body tell me how to code a table with dual primary keys? The table 'borrower' has two PKs each one has been used in other tables within the same schema as single PKs

Here is what I have tried:
create table borrower(user_id int primary key,
issn varchar(15) primary key);
Error: create table / primary key multiple primary keys for table 'borrower' are not allowed.

I also tried this:
create table borrower(user_id int ,
issn varchar(15),
primary key user_id, issn);
ERROR: parser: parse error at or near "user_id" at character 68
and
create table borrower(user_id int ,
issn varchar(15),
(primary key user_id, issn));
ERROR: parser: parse error at or near "( " at character 56
thanks
Janet

On Wed, Feb 04, 2004 at 15:15:45 -0000,
Bantamess <bantamess (AT) yahoo (DOT) co.uk> wrote:
Use UNIQUE and NOT NULL constraints on one of the two keys. In references
to that key, you will need to specify the column name as the default
column name is the primary key.

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"Bantamess" <bantamess (AT) yahoo (DOT) co.uk> writes:
Do you mean a two-column composite primary key? Two independent primary
keys is nonsensical --- you should pick just one of them to be
considered the "primary" key.

If you want a composite primary key, the syntax is
primary key (f1, f2)

regards, tom lane

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Janet,

This is, I think, what you want. However, you have a syntax error in your
primary key constraint declaration:

CONSTRAINT borrower_pk PRIMARY KEY (user_id, issn)

Also, both user_id and issn should be declared NOT NULL.

Overally, I suggest picking up an "introduction to SQL book", such as "SQL
Queries for Mere Mortals."

--
-Josh Berkus
Aglio Database Solutions
San Francisco


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