Oracle数据库中，通过function的方式建立自增字段

Oracle数据库无自增字段设置，可以通过function的方式设置字段自增来作为ID。

1、创建表tSequence来存储各表的next ID。

2、创建function类似如下：

CREATE OR REPLACE FUNCTION "FUNC_NEXTID"
(tablename in varchar2) return number is

  nextid number(12);
begin
  begin
    select nvl(max(id),-1) into nextid from tSequence where upper(name) = upper(tablename);
  exception
    when no_data_found then nextid := 0;
  end;

  if nextid = -1 then
    INSERT INTO tSequence(name,id) VALUES(tablename,1);
    nextid := 1;
  else
    update tSequence set id = id+1 where upper(name) = upper(tablename);
    select nvl(max(id),-1) into nextid from tSequence where upper(name) = upper(tablename);
  end if;

  return(nextid);
end FUNC_NEXTID;

3、调用方法

insert into tablename ( ID, 列1,,列2) values (func_nextid('tablename'), '列1值', '列2值' )