[Zope] constraint in postgres

[Olaf Zanger]

hi there,

i want to make some constraint-restrictions with two tables in postgres 

create table address ( id serial,  country_id int4, ....);
and
create table country (id serial, ...);

i want to make sure that the country-row with "id=2" is not deleted 
if there is still a corresponding data-set with "country_id=2" in the address table.

e.g.

address: 1, 2, ...
country: 2, ...

now country wouldn't be allowed to be deleted. 

how to do that?

thanks fo help

olaf
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soli-con Engineering Zanger
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