Обсуждение: sql scripts

I am new to postgres and your mailing lists, please let me know if I
am posting in the wrong list.

I am working on creating my first database in Postgres.  In the
script that will create all the tables for the firs time, I would
like to have a conditional statement to delete a table, if it
already exists.  I know the other databases create such a condtional
statement for you when you export the schema.  What would such a
conditional statement look like in Postgres's sql?

sam

On Sat, 18 Oct 2003, Sam Carleton wrote:

> I am working on creating my first database in Postgres.  In the
> script that will create all the tables for the firs time, I would
> like to have a conditional statement to delete a table, if it
> already exists.

As far as I know, there is no way to do that in PostgreSQL's standard
SQL language.  But it doesn't matter -- as long as the DROP TABLE
command is in it's own transaction, you can unconditionally drop the table
and ignore any errors.

Regards,

David.

If it's a bash script you could use:

#####
SomeTable=<Table you're about to create>
TableTest=$(psql -d <your new db> -U <its owner> -ntc "select relname from
pg_class where relname='$SomeTable'")
[[ -n "$TableTest" ]] && psql -d <your new db> -U <its owner> -nc "drop
table $SomeTable"
#####


It's not quite "in postgres's sql", but it could get the job done


>-----Original Message-----
>From: Sam Carleton [mailto:ehc@linux-info.net]
>Sent: Saturday, October 18, 2003 22:37
>To: pgsql-admin@postgresql.org
>Subject: [ADMIN] sql scripts
>
>
>I am new to postgres and your mailing lists, please let me know if I
>am posting in the wrong list.
>
>I am working on creating my first database in Postgres.  In the
>script that will create all the tables for the firs time, I would
>like to have a conditional statement to delete a table, if it
>already exists.  I know the other databases create such a condtional
>statement for you when you export the schema.  What would such a
>conditional statement look like in Postgres's sql?
>
>sam
>
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