mysql海量数据查询优化

        string wheresql = " and c.id >= (select min(id) from (select id from caiji order by id desc limit 0,4000) as t) ";


        sql = "select count(*) from caiji as c where 1 " + wheresql + consql;


 sql = "select c.id as id, c.cid as cid, l.ctitle as leibie, c.ctitle as ctitle, c.cdate as cdate, c.url as url, c.cjdate as cjdate, c.zhtitle as zhtitle from caiji as c join leibie as l where  1 " + wheresql + "  and c.cid = l.cid  " + consql + " order by c.id desc  limit " + (curpage - 1) * perpage + "," + perpage;
       

select id from caiji where id <= (select min(id) from ( select id from caiji where cid=5  order by id desc limit 10000,1 ) as t) and cid=5  order by id desc limit 0,10

其中，10000为总记录数，为第几页页数*每页记录数

            sql = "select count(*) from caiji as c  join (select id from caiji order by id desc limit 0, 10000 ) as b on c.id = b.id   where 1  " + consql;

        else
        {

            sql = "select count(*) from caiji ";
        }

 

      if (Request.QueryString["cid"] != null && Request.QueryString["cid"].Length > 0)
        {
    
            tmpsql = "select id from caiji where id <= (select min(id) from ( select id from (select c.id from caiji as c  join (select id from caiji order by id desc limit 0, 10000 ) as b on c.id = b.id   where 1 " + consql + " ) as p  order by id desc limit " + (curpage - 1) * perpage + ",1 ) as t)   order by id desc limit 0," + perpage;
            sql = "select c.id as id, c.cid as cid, l.ctitle as leibie, c.ctitle as ctitle, c.cdate as cdate, c.url as url, c.cjdate as cjdate, c.zhtitle as zhtitle from caiji as c join leibie as l  on  c.cid = l.cid  right join (" + tmpsql + ") as r on r.id = c.id";
            //Response.Write(sql + "
");
        }else
 
        {
            tmpsql = "select id from caiji where id <= (select min(id) from ( select id from caiji  order by id desc limit " + (curpage-1)*perpage + ",1 ) as t)   order by id desc limit 0," + perpage;
            sql = "select c.id as id, c.cid as cid, l.ctitle as leibie, c.ctitle as ctitle, c.cdate as cdate, c.url as url, c.cjdate as cjdate, c.zhtitle as zhtitle from caiji as c join leibie as l  on  c.cid = l.cid  right join (" + tmpsql + ") as r on r.id = c.id";
        }