create sequence foo;

create table bar (x int primary key default (next value for foo), y int);

while 1=1 do

  insert into bar ( y )

    select <<<something>>> from <<<something>>>;

  rollback;

end while;

while 1=1 do

  insert into bar (x,y)

    select next value for foo, <<<something>>> from <<<something>>>;

  rollback;

end while;

Item_func_nextval::val_int (this=0x7f1e78cca8a8) at /usr/src/debug/MariaDB-10.4.24/src_0/sql/item_func.cc:6877