Re: Error dropping non-existent tables

Thanks Bruno. A silly followup question =)

On Sat, 20 Nov 2004 10:51:13 -0600, Bruno Wolff III <bruno@wolff.to> wrote:
> On Fri, Nov 19, 2004 at 21:38:33 -0800,
>  Baldeep Hira <baldeephira@gmail.com> wrote:
> >
> > I am able to drop tables in PostgreSQL, but the problem arises when
> > the table does not exist and I try to execute a "drop table" command.
>
> The simplest fix is to do the drop table outside of a transaction (so
> that the error in the drop doesn't break the rest of your script).
> If that won't work for you then you can write a custom function that
> looks in the system catalog to see if the table exists before trying
> the drop.
>
How do I move the "DROP TABLE" commands into a separate transaction? I
could move all the "DROP TABLE" commands into a separate sql-script
file, but then I never know which of the tables are existing in the
database, thus that script will break as well.   When I execute a
bunch of SQL commands from a script file, do all of them form a single
transaction?  Anyway, I can have multiple transactions from a single
script file?

Currently my sql-script file looks like this.

DROP TABLE table1 CASCADE;
DROP TABLE table2 CASCADE;
DROP TABLE table3 CASCADE;
DROP TABLE table4 CASCADE;

CREATE TABLE table1 (
    name   VARCHAR(255)   NOT NULL,
    id         INTEGER            NOT NULL
);

CREATE TABLE table2 (
    id        INTEGER     NOT NULL,
    type    INTEGER     NOT NULL
);

CREATE TABLE table3 (
    id        INTEGER     NOT NULL,
    p_id    INTEGER     NOT NULL,
    CONSTRAINT fk_table3 FOREIGN KEY (id)
      REFERENCES table2 (id)
);

CREATE TABLE table4 (
    id          INTEGER            NOT NULL,
    name    VARCHAR(255)    NOT NULL,
    CONSTRAINT pk_table4 PRIMARY KEY (id),
    CONSTRAINT u_table4   UNIQUE (name)
);

thanks,
Baldeep.