Difference: Uniq. Constraint & Index ?

alter table my_emp
  add constraint u_con unique (col_a) ;

create unique index u_index on my_emp (col_a);

What is the difference between Unique Constraint and Unique Index ? And under what circumstance(s) will their difference come into play ?

thanks Received on Mon Oct 16 2006 - 18:58:31 CDT