Question

我写了一个PL / SQL脚本来将序列的值设置为表的主键的最大值：

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，则会出错：

ORA-08004：序列MBR_SEQ.NEXTVAL低于MINVALUE且无法实例化

ORA-06512：第10行

最简单的说法是“通过increment_amount递增序列，但不要低于MINVALUE”？

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;

如何在Oracle 10g PL / SQL中获得序列的MINVALUE？

1 个答案: