1. 代码看起来没有错啊,看看连接有问题. 这是一个在我计算机上通过的.string strConn, strSQL;
strConn = "Provider=SQLOLEDB;Data Source=(local)\\NetSDK;" +
"Initial Catalog=Northwind;Trusted_Connection=Yes;";
OleDbConnection cn = new OleDbConnection(strConn);
cn.Open();
strSQL = "SELECT CustomerID, CompanyName FROM Customers";
OleDbCommand cmd = new OleDbCommand(strSQL, cn);
OleDbDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
Console.WriteLine(rdr["CustomerID"] + " – " + rdr["CompanyName"]);
rdr.Close();2.>怎么用代码实现树状。多谢,我刚学,几天也没完成
参考:
如何在C#中快速实现数据库树形结构
http://www.aspxcn.com/dotnetbbs/View.aspx?fbId=23&Id=57150
strConn = "Provider=SQLOLEDB;Data Source=(local)\\NetSDK;" +
"Initial Catalog=Northwind;Trusted_Connection=Yes;";
OleDbConnection cn = new OleDbConnection(strConn);
cn.Open();
strSQL = "SELECT CustomerID, CompanyName FROM Customers";
OleDbCommand cmd = new OleDbCommand(strSQL, cn);
OleDbDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
Console.WriteLine(rdr["CustomerID"] + " – " + rdr["CompanyName"]);
rdr.Close();2.>怎么用代码实现树状。多谢,我刚学,几天也没完成
参考:
如何在C#中快速实现数据库树形结构
http://www.aspxcn.com/dotnetbbs/View.aspx?fbId=23&Id=57150
2。http://www.aspxcn.com中一篇文章写过!
========================
数据库表设计
必须包含下列字段:
字段名 字段类型 字段说明 PrimaryKey
==========================================
NodeID varchar 节点标识 Yes
NodeName varchar 节点显示名
ParentID varchar 父节点标识
....//节点信息类
public class NodeInfo
{
public string NodeID;
public string NodeName;
public string ParentID;
public string PrivateData;
///...更多的属性定义
public NodeInfo()
{
}
}public class UserTool
{
public static void Load(DataTable dt,ref TreeView tv)
{
Hashtable ht = new Hashtable();
int iCount = dt.Rows.Count;
DataRow dr;
NodeInfo nodeInfo;
string [] keyArray = new string[iCount];//保存哈西表中的键值
//创建所有树节点,保存在哈西表中
for(int i=0;i<iCount;i++)
{
nodeInfo = new NodeInfo(); dr = dt.Rows[i];
nodeInfo.NodeID = dr["NodeID"].ToString();
nodeInfo.NodeName = dr["NodeName"].ToString();
nodeInfo.ParentID = dr["ParentID"].ToString();
nodeInfo.PrivateData = dr["ParentID"].ToString();
///...更多的字段处理
keyArray[i] = nodeInfo.NodeID;
TreeNode tn = new TreeNode(nodeInfo.NodeName); //创建节点
tn.Tag = nodeInfo; //设置节点数据区
ht.Add(nodeInfo.NodeID,tn);
}
//建立节点关系,并将根节点加入到TreeView中
for(int i=0;i<iCount;i++)
{
TreeNode tn = (TreeNode)ht[keyArray[i]];
nodeInfo = (NodeInfo)tn.Tag;
if(nodeInfo.ParentID == null || nodeInfo.ParentID == "")
tv.Nodes.Add(tn);//这是根节点
else //这是子节点
{
TreeNode tnd1 = (TreeNode)ht[nodeInfo.ParentID];//找父节点对象,注意:可能找不到父节点对象
if(tnd1!=null)
tnd1.Nodes.Add(tn);//找到父节点:把该节点加到父节点的子节点列表中
else
{
//未找到父节点:或把它设为根节点,或抛弃,你看着办了
//tv.Nodes.Add(tn); //设为根节点
}
}
}
}
}