SQLite 3.39

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table franck ( val int unique );
✓
insert into franck values (-1),(1) ;
✓
select val from franck;

val

-1

1

update franck set val=-val;

{
  "code": "SQLITE_CONSTRAINT_UNIQUE"
}

select val from franck;

val

-1

1