You can't set the next value of a sequence directly in Oracle; you have to drop and recreate the sequence. Here's a way to do it if you need to set the next value to the largest value in a particular column plus 1:
declare
nextId number;
begin
select coalesce(max(PrimaryID), 0) + 1 into nextId from Table;
execute immediate 'drop sequence PrimaryIDSeq';
execute immediate 'create sequence PrimaryIDSeq minvalue ' || nextId;
end;
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