- Sequence中cache的影响,每新建一个连接,next value值增加increment * cache.如果加上order,则会按顺序生成值.
1 create sequence myseq start with 5 increment by 5 cache 100;
2
3 Connection1
4
5 values next value for myseq;
6
7 5
8
9 values next value for myseq;
10
11 10
12
13 Connection2
14
15 values next value for myseq;
16
17 505
18
19 Connection3
20
21 select next value for myseq from sysibm.sysdummy1;
22
23 1005
1 create sequence myseq cache 10 order;
2
3 Connection1
4
5 values next value for myseq;
6
7 1
8
9 Connection2
10
11 values next value for myseq;
12
13 2
14
15 Connection1
16
17 values next value for myseq;
18
19 3
- Unit of Work的特征之一是一系列可以恢复的操作
- 用户调用UDT需要DB2 EXECUTE权限
- 取消所有DML权限:REVOKE ALL ON TBL FROM USER A
- CREATE VIEW V1 AS SELECT A FROM T WHERE C > 100 WITH CHECK OPTION。其中WITH CHECK OPTION的作用是使得所有插入更新V的值都必须满足C>100。
- TABLE可以被显示的lock,可以在LOCK语句中指定。