Need help on triggers - postgres 9.1.2

Hi

I have a postgres 9 database, inside this database I need to create a new
table called *center_changed* that gets inserted by any change that take
place in a table called *center*. So I need to create trigger to do this.

*Example: *

Table name*: center*(c_cde, c_dsc, ops_cde, grp_cde);

Now on the table called *center , *I need to create an INSERT and UPDATE
trigger will insert the *c_cde * of the inserted or updated *center* into
the *center_changed* table

Please help me

I have this syntax below, but please help me with the overall query.

CREATE TRIGGER check_center

BEFORE INSERT OR UPDATE

ON *cente*r FOR EACH ROW

EXECUTE PROCEDURE check_center_changes();

Thanks

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