DB2的Sequence 对象(2)

1、create
             CREATE SEQUENCE <sequence-name>
               AS data-type                           默认 As Integer
              START WITH <numeric-constant>  
          INCREMENT BY <numeric-constant>               默认 INCREMENT BY 1
           MINVALUE <numeric-constant> | NO MINVALUE    默认 NO MINVALUE
           MAXVALUE <numeric-constant> | NO MAXVALUE    默认 NO MAXVALUE
           NO CYCLE | CYCLE                             默认 NO CYCLE
           CACHE <numeric-constant> | NO CACHE          默认 CACHE 20
           NO ORDER | ORDER                             默认 NO ORDER

2、序列取值
   取下一个值：
      DB2:    NEXTVAL FOR 序列 或 NEXT VALUE FOR 序列
   取当前值：
      DB2:    PREVIOUS VALUE FOR 序列  或 PREVVAL FOR 序列


3、序列设置开始值
      DB2：ALTER SEQUENCE 序列名  RESTART WITH 下一值

4、修改
 修改最大值：   ALTER SEQUENCE <sequence_name> MAX VALUE <numeric-constant> | NO MAXVALUE
 修改最小值：   ALTER SEQUENCE <sequence_name> MIN VALUE <numeric-constant> | NO MINVALUE （此值需要比当前值小）
 修改步长：    ALTER SEQUENCE <sequence_name> INCREMENT BY <numeric-constant>;
 修改CACHE值： ALTER SEQUENCE <sequence_name> CACHE <numeric-constant> | NO CACHE
 修改循环属性: ALTER SEQUENCE <sequence_name> <CYCLE | NO CYCLE>
 修改排序属性：ALTER SEQUENCE <sequence_name> <ORDER | NO ORDER>
 从新计数：    ALTER SEQUENCE <sequence_name> RESTART | RESTART WITH <numeric-constant>

5、DROP
     DB2：    DROP SEQUENCE <sequence_name>;
6、例子
  CREATE SEQUENCE MY_SEQ
    AS INTEGER 
     START WITH 10001000 
      INCREMENT BY 1 
      MINVALUE 10000000 
      MAXVALUE 69999999 
      CYCLE 
      NO CACHE 
     ORDER;

  select  nextval for MY_SEQ from  sysibm.sysdummy1