Hey Stefan,
For surrogate keys there is no reason to calculate values manually.
You should use sequences instead. Please, see
http://www.postgresql.org/docs/8.3/static/sql-createsequence.html
You may also use a SERIAL data type which creates a sequence
for you automatically upon its creation. Please, see
http://www.postgresql.org/docs/8.3/static/datatype-numeric.html#DATATYPE-SERIAL
Since you execute INSERT command without specifying an "id" column,
and there is no default value for it, then the default is NULL. So, you need
to define a default and the best solution to define it as next value of sequence.
--
Regards,
Dmitriy
