这段代码怎么优化一下,查询速度实在是太慢了??
代码如下,是做的一个报表统计查询,用了三个datagrid控件绑定,不过查询效率很低,大家看怎么来优化一下好

private   void   Page_Load(object   sender,   System.EventArgs   e)
{
if(!Page.IsPostBack)
{
this.lbl_start_datem.Text=Session[ "start_datem "].ToString();
this.lbl_end_datem.Text=Session[ "end_datem "].ToString();


string   str1,str2;
str1=Session[ "start_datem "].ToString();
str2=Session[ "end_datem "].ToString();

SqlConnection   conn=new   SqlConnection(System.Configuration.ConfigurationSettings.AppSettings[ "DBConnection_tw "]);

string   sql= "select   case   when   m.loc_code   is   null   then   s.stano   else   m.loc_code   end   as   loc_code,s.station,s.c3, "+
"isnull(m.ps,0)   as   ps,isnull(m.weig,0)   as   weig,isnull(m.charge,0)   as   charge   from "+                
"(select   loc_code,count(*)   as   ps,sum(weig)   as   weig,sum(charge)   as   charge   from   manifest   where   datem   between   ' "+str1+ " '   and   ' "+str2+ " '   group   by   loc_code) "+
"m   full   outer   join   stat   s   on   m.loc_code=s.stano ";

string   sql1= "select   d.c3,sum(d.ps)   as   ps,sum(d.weig)   as   weig,sum(d.charge)   as   charge   from( "+sql+ ")   d   group   by   c3   ";

string   sql2= "select   '統計(總) '   as     統計,   sum(d1.ps)   as   ps,sum(d1.weig)   as   weig,sum(d1.charge)   as   charge   from   ( "+sql1+ ")   d1 ";
SqlDataAdapter   myCommand   =new   SqlDataAdapter(sql,conn);
SqlDataAdapter   myCommand1   =new   SqlDataAdapter(sql1,conn);
SqlDataAdapter   myCommand2   =new   SqlDataAdapter(sql2,conn);


DataSet   ds=new   DataSet();
DataSet   ds1=new   DataSet();
DataSet   ds2=new   DataSet();
myCommand.Fill(ds);
myCommand1.Fill(ds1);
myCommand2.Fill(ds2);
dg.DataSource=ds;
dg1.DataSource=ds1;
dg2.DataSource=ds2;
dg.DataBind();
dg1.DataBind();
dg2.DataBind();
}
}


------解决方案--------------------
改写成存储过程吧。这样性能会提高不少
------解决方案--------------------
改善查询性能:
1.使用存储过程
2.建立合适的索引
3.加上合理的where条件~
------解决方案--------------------
写成存储过程吧
------解决方案--------------------
不说你
改善查询性能:
1.使用存储过程
2.建立合适的索引
3.加上合理的where条件~
-----------------------
就说你的SQL说起,构造复杂的SQL语句,使用StringBuilder的性能就比+的高
再者,web开发,请注意SQL防注入,使用参数的SQL语句或存储过程,或写防注入的函数.
然后是,干吗使用3个Command,你用分号分开的SQL或存储过程,分开执行,返回一整个DATASET,不更好
还有没有必要每次统计的,请放到另外一个表,等用户重新统计,再统计,这样可以节约非常多的资源
之后还有很多,不说了