Oracle序列没有生成

时间:2013-03-19 03:55:25

标签: oracle oracle11g

我有一个表人包含的字段是personName,personId并且没有指定主要我在表中添加了一些值。表Person中的值为

 ('muni',1)   
 ('Ganesh',1) 

我需要将主键添加为personId,并将列修改为autogenerated。所以,我尝试通过以下查询生成序列,以生成触发器

declare           
id  number;     
begin  
select max(rownum)+1 into id from Person;  
execute immediate 'create sequence personseq start with '||to_char(id);  
end;

如果我在表中的值执行上面的查询,那么它正确执行,但是当我有空表表示表中没有条目时,上面的查询不生成序列。

我也试过if语句。

declare  
id  number;  
begin  
select max(rownum)+1 into id from Person;  
if (id=null) then  
execute immediate 'create sequence personseq start with '||to_char(1);  
else  
execute immediate 'create sequence personseq start with '||to_char(id);  
end if;  
end;

系统显示错误号为ORA01722,表示我给出的号码无效号码。但我不知道错误在哪里? 任何帮助高度赞赏。

3 个答案:

答案 0 :(得分:1)

试试这个

select nvl(max(rownum),0)+1 into id from Person; 

当表为空时,max(rownum)将返回null,当您向值添加null时将始终返回null,因此您需要将任何空值转换为0,以便0 + 1将返回1而不是null

答案 1 :(得分:1)

upd:刚注意到比计数/ rownum更重要的缺陷。

id=null。从不这样做,这不起作用。

您可以通过以下方式检查值是否为空:id is null

NULLS

使用count(*)

12:03:55 SYSTEM@saz-dev> create table person as
12:04:05   2  select 'muni' name, 1 attribute from dual union all
12:04:32   3  select 'ganesh' name, 1 attribute from dual;

Table created.

Elapsed: 00:00:00.07
12:04:47 SYSTEM@saz-dev> ed
Wrote file S:\tools\buffer.sql

  1  declare
  2  id  number;
  3  begin
  4  select count(*)+1 into id from person;
  5  execute immediate 'create sequence personseq start with '||to_char(id)||' increment by 1';
  6* end;
12:05:52   7  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.06
12:05:53 SYSTEM@saz-dev> select object_name from user_objects where object_name = 'PERSONSEQ';

OBJECT_NAME
---------------------------------------
PERSONSEQ

Elapsed: 00:00:00.08
12:06:16 SYSTEM@saz-dev> truncate table person;

Table truncated.

Elapsed: 00:00:00.32
12:06:27 SYSTEM@saz-dev> drop sequence personseq;

Sequence dropped.

Elapsed: 00:00:00.20
12:06:33 SYSTEM@saz-dev>  declare
12:06:38   2   id  number;
12:06:38   3   begin
12:06:38   4   select count(*)+1 into id from person;
12:06:38   5   execute immediate 'create sequence personseq start with '||to_char(id)||' increment by 1';
12:06:38   6   end;
12:06:39   7  /

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.03
12:06:40 SYSTEM@saz-dev> select personseq.nextval from dual;

   NEXTVAL
----------
         1

Elapsed: 00:00:00.04

答案 2 :(得分:0)

像这样创建一个序列

CREATE SEQUENCE person_seq
 START WITH     1000
 INCREMENT BY   1
 NOCACHE
 NOCYCLE;

比使用 - ' person_seq.nextval'每次插入新记录
e.g。

插入人(姓名,身份证)值(' abc',person_seq.nextval)