 
private void Display(string parentid, String space) 
{ 
DataTable dt; 
String strSQL; 
strSQL = "Select * From Tree Where ParentID =" + parentid + " Order By ClassID DESC"; 
SqlDataAdapter sda = new SqlDataAdapter(strSQL, conn); 
DataSet ds = new DataSet(); 
sda.Fill(ds, "Tree"); 
dt = ds.Tables["Tree"]; 
if (dt.Rows.Count > 0) 
{ 
foreach (DataRow dr in dt.Rows) 
{ 
strOpinion += space + "<font color=red>[" + dr["JobClassName"].ToString() +"<br>"; 
Display(dr["ClassID"].ToString(), "&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;" + space,false); 
} 
} 
} 

很明顯，這種做法是每個父分類都得建立一次連接，完全浪費資源
現(xiàn)在一次取出所有分類，使用DataView的RowFilter屬性做多次過濾
關鍵代碼

復制代碼代碼如下:

 
public partial class tree_Default : System.Web.UI.Page 
{ 
DataTable dt = null; 
protected void Page_Load(object sender, EventArgs e) 
{ 
if (!IsPostBack) 
{ 
bind(0); 
} 
} 
public void bind(int pid) 
{ 
DataTable dt1 = bindTree(pid); 
foreach (DataRow dr in dt1.Rows) 
{ 
int id = Convert.ToInt32(dr["classid"].ToString()); 
if (pid == 0) 
Response.Write("<div style='width:100%;float:right;'><h3>" + dr["jobclassname"].ToString() + "</h3></div>"); 
else 
Response.Write("<div style='width:25%;float:left;'>"+dr["jobclassname"].ToString()+"</div>"); 
bind(id); 
} 
} 
public DataTable bindTree(int pid) 
{ 
if (dt == null) 
dt = new data().getCatelogs(); 
DataView root = dt.DefaultView; 
root.RowFilter = "Parentid=" + pid; 
return root.ToTable(); 
} 
} 