Single Row Table? - Mailing list pgsql-general

Hi,

I have got a table which is supposed to contain only one row. It does not have any primary keys defined.

So, essentially, when a new insert happens in that table, I would like it (the insert) to fail if there is already a row existing in that table.

How can I do that? Can I add any constraints? Or do I need to write a separate trigger for the same?

Thanks and regards,

Yateen V. Joshi