学步园

select t1.*,rownum rn from (select * from emp) t1;
select t1.*,rownum rn from (select * from emp) t1 where rownum<=10;
--在分页的时候，可以把下面的sql语句当做一个模板使用
select * from (select t1.*,rownum rn from (select * from emp) t1 
where rownum<=10) where rn>=6;
--开发一个包
--1、创建一个包
create or replace package testpackage 
as 
  type cursor_test is ref cursor;
end testpackage;
--开始编写分页的过程
create or replace procedure fenye(tableName in varchar2,
                                  pageSize in number, --每页显示记录数
                                  pageNow in number,
                                  myRows out number,--总记录数
                                  myPageCount out number,--总页数
                                  p_cursor out testpackage.cursor_test)
is
  --定义sql语句 字符串
  v_sql varchar2(1000);
  --定义2个整数
  v_begin number:=(pageNow-1)*pageSize+1;
  v_end number:=pageNow*pageSize;
begin
  v_sql:='select * from (select t1.*,rownum rn from (select * from 
'||tableName||' order by sal) t1 where rownum<='||v_end||')
 where rn>='||v_begin||'';
  --把游标和sql关联
  open p_cursor for v_sql;
  --计算myRows和myPageCount
  --组织一个sql
  v_sql:='select count(*) from '||tableName||'';
  --执行sql，并把返回的值，赋给myRows
  execute immediate v_sql into myRows;
  --计算myPageCount
  if mod(myRows,pageSize)=0 then
    myPageCount:=myRows/pageSize;
  else
    myPageCount:=myRows/pageSize+1;
  end if;
  --关闭游标
  --close p_cursor;
end;