oracle - 如何在 Oracle 10g PL/SQL 中获取序列的 MINVALUE？

Question

我编写了一个 PL/SQL 脚本来将序列的值设置为表主键的最大值:

DECLARE
  max_idn NUMERIC(18, 0);
  seq_nextval NUMERIC(18, 0);
  increment_amount NUMERIC(18, 0);
BEGIN
  SELECT MAX(mbr_idn)
  INTO max_idn
  FROM mbr;

  SELECT mbr_seq.nextval
  INTO seq_nextval
  FROM DUAL;
  
  increment_amount := max_idn - seq_nextval;

  EXECUTE IMMEDIATE 
    'ALTER SEQUENCE mbr_seq
     increment by ' || increment_amount;
END;

但是，如果序列的 MINVALUE 大于最大主键，我会收到错误消息:

ORA-08004: sequence MBR_SEQ.NEXTVAL goes below MINVALUE and cannot be instantiated

ORA-06512: at line 10

说“按 increment_amount 增加序列，但不要低于 MINVALUE”的最简单方法是什么？

Answer 1

您可以查询 DBA_SEQUENCES 表以获取 MIN_VALUE

SELECT min_value
  INTO l_min_value
  FROM all_sequences
 WHERE sequence_name = 'MBR_SEQ'
   AND owner = <<sequence owner>>

然后您可以将其合并到您的代码中，即

increment_amount := GREATEST( max_idn, l_min_value ) - seq_nextval;