如何使用循环更改Oracle Sequence？

Question

希望有人能提供帮助.当我尝试在表中插入某些内容时,它会给出错误,指出主键已经存在.所以我需要重置我的序列,以便它始终是max(id)+1.

该表称为"People",有2列(ID,Name).该序列称为SEQ.

我正在考虑做一个循环.从dual中选择SEQ.nextval n次.这个n = max(id)-SEQ.currval

这会是什么工作？以及如何将其添加到语法中？

非常感谢.

Answer 1

declare
  l_MaxVal  pls_integer;
  l_Currval pls_integer default - 1;
begin
  select max(id)
    into l_MaxVal
    from people;
  while l_Currval < l_Maxval
  loop
    select my_seq.nextval
      into l_Currval
      from dual;
  end loop;
end;

Answer 2

如果这是一次性的,你可以使用alter sequence alter sequence sequenceName increment by val; 而val是最大+1,然后调用get nextVal,然后将增量设置回1.

我把下面的内容放在一起,告诉你如何在没有循环的情况下完成它.

create sequence changeValue start with 18 increment by 1 nocache ;
select changeValue.nextval from dual ;
/

NEXTVAL                
---------------------- 
18  



set serveroutput on
declare
 maxVal     number := 24 ;
 curVal     number ;
 diffVal      number ;
 incrementVal number ;


 procedure alterSequence(seqName in varchar2, incVal in number) as
    s varchar2(500);
    begin
       s := 'alter sequence ' || seqName || ' increment by  ' || incVal ;
       dbms_output.put_line(s);
       execute immediate s;
    end alterSequence;
begin
    --(done in 11gr2 so if in earlier version select into)
     curVal := changeValue.currval ;
    dbms_output.put_line('curValue=>' || curVal );
    diffVal :=  maxVal - curVal ;
    dbms_output.put_line('diffVal=>' || diffVal );

    alterSequence ( 'changeValue' , diffVal + 1 );
    incrementVal   := changeValue.nextval ;
    dbms_output.put_line('incrementVal=>' || incrementVal );
    alterSequence ( 'changeValue' , 1 );
    curVal := changeValue.currval ;
    dbms_output.put_line('curValue=>' || curVal ); 
end ;
/


curValue=>18
diffVal=>6
alter sequence changeValue increment by  7
incrementVal=>25
alter sequence changeValue increment by  1
curValue=>25

或者更好,正如@Dave建议的那样,只需删除并重新创建具有可接受的Start With值的序列.