It's all in the excellent manual: datatype serial (also available in PDF )

Note that:

Prior to PostgreSQL 7.3, serial implied UNIQUE. This is no longer automatic. If you wish a serial column to have a unique constraint or be a primary key, it must now be specified, just like any other data type.

(Btw: a hint regarding the database name: call it postgresql, postgres, or even Pg, but calling it 'Postgre' makes the same impression as writing PERL instead of Perl).

In reply to Re^3: Working with Postgresql serial data type in Perl by erix
in thread Working with Postgresql serial data type in Perl by vendion

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