this reads in every row from the table, using a cursor loop.

there are other sql statemnets that are processed. these validate the contents of the data, but these statements don't run on this table.

script is basically:

cursor cur
select * from tablea
where columna is null
for update of columna

begin
for records in cur loop
if cur.columnb > 1 then ....
err=1;
etc.
update tablea set columna=err
where current of cur;
end loop;
end;