oracle禁用外键关联约束

declare
  v_sql varchar2(4000);
begin
  for item in (select 'alter table ' || t.table_name ||
                      ' disable constraint ' || t.constraint_name as sql_text
                 from user_constraints t
                where t.constraint_type = 'R' and t.status = 'ENABLED') loop
    v_sql := item.sql_text;
    execute immediate v_sql;
  end loop;
end;
/