同事来问测试环境上的一个sequence.currval 为什么取不到当前值。我说你试试nextval就能取到了。
metalink ORA-8002 When Selecting CURRVAL From Sequence [ID 1019173.102]
文章中说到：
Before you can access CURRVAL for a sequence, you must first initialize the
sequence with NEXTVAL.
下面做个小的实验：
SQL> CREATE SEQUENCE t_sequence START WITH 1000;
Sequence created
创建序列后，直接使用currval取序列的当前记录，返回错误：ORA-08002
SQL> SELECT t_sequence.CURRVAL FROM DUAL;
SELECT t_sequence.CURRVAL FROM DUAL
ORA-08002: sequence T_SEQUENCE.CURRVAL is not yet defined in this session
SQL> SELECT t_sequence.nextval FROM DUAL;
NEXTVAL
----------
1000
SQL> SELECT t_sequence.CURRVAL FROM DUAL;
CURRVAL
----------
1000
SQL> SELECT t_sequence.nextval FROM DUAL;
NEXTVAL
----------
1001