Given this setup
create type myenum_one as enum('foo', 'bar', 'baz');
create table mytable (
myvalue myenum_one
);
alter table mytable
add constraint mycheckconstraint check (myvalue != 'bar');
insert into mytable values ('foo');
create type myenum_two as enum('foo', 'bar');
It then fails on when trying to alter the column type
alter table mytable
alter column myvalue type myenum_two using myvalue::text::myenum_two;
With error
ERROR: operator does not exist: enum_two <> enum_one
HINT: No operator matches the given name and argument types. You might need to add explicit type casts.
CodePudding user response:
You need to drop the check constraint before altering the column type, and the recreate it after (if it's still relevant), like so
alter table mytable
drop constraint mycheckconstraint;
alter table mytable
alter column myvalue type myenum_two using myvalue::text::myenum_two;
alter table mytable
add constraint mycheckconstraint check (myvalue != 'bar');