ORCAL 语句妙用

针对某张表进行插入还是对原有记录进行修改

merge into 表名 a using
      (select  需要查找的记录关键字值 as userid from dual) b on (a.userid = b.userid )
when matched then
     update  set newnum = newnum + 1
when not matched then
     insert  values(关键字值,1)