c#代码连接数据库，以及进行crud操作等
在C#的Web.config 里
之间加入下面代码：
.cs代码文件里大致总结如下：
//获取数据库字符串连接字符
static String strSqlConn = System.Configuration.ConfigurationManager.AppSettings["DbConnString"];
String sql = "select max(nrow) as maxrow from treenode";
//using确保资源能被释放//连接数据库
using ( SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
maxrow = reader.GetInt32(reader.GetOrdinal("maxrow"));
}
}
catch (SqlException ex)
{
throw ex;
}
}
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下面是一个具体的.cs连接数据库进行操作的代码源文件
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Data;
///
/// TreeDao 的摘要说明
///
public class TreeDao
{
//最大的行数
static int maxrow;
//获取数据库字符串连接字符
static String strSqlConn = System.Configuration.ConfigurationManager.AppSettings["DbConnString"];
//静态的存取删除树根节点的下面节点集合、
static List
SqlConnection conns = null;
///
/// 查询出最大行数
///
public static int queryMax()
{
String sql = "select max(nrow) as maxrow from treenode";
//using确保资源能被释放//连接数据库
using ( SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
maxrow = reader.GetInt32(reader.GetOrdinal("maxrow"));
}
}
catch (SqlException ex)
{
throw ex;
}
}
return maxrow;
}
///
/// 将查询出来的所有节点组装成树
///
public static TreeNode assemble(List
{
//树的最大行
int c = queryMax();
//将树的所有节点放入字典里（这里用数据字典就可以避免双重（多重）循环，提高查询效率，避免n次级增长）
Dictionary
for (int i = 0; i < list.Count; i++)
{
d.Add(list[i].nid, list[i]);
}
//从树的最大行开始，直到根节点（寻找绑定儿子节点）
while (c > 1)
{
for (int j = 0; j < list.Count; j++)
{
if (list[j].nrow == c)
{
//如果该子节点有父节点
if (list[j].pid != null)
{
//将字典里的父节点的儿子属性集合加上该子节点
d[list[j].pid].children.Add(list[j]);
}
}
}
c--;
}
//取出根节点并将它返回
for (int k = 0; k < list.Count; k++)
{
if (list[k].nrow == 1)
return d[list[k].nid];
}
//如果没有找到根节点就返回Null
return null;
}
///
/// 查询出所有的树节点并将之组装成树（调用组装方法）
///
public static TreeNode queryAll()
{
List
String sql = "select t.nid,"
+ "t.name,"
+ "t.nrow,"
+ "t.pid,"
+ "t.havechild "
+ " from treenode t where t.isdelete=0 ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
TreeNode t = new TreeNode();
t.nid = reader["nid"].ToString();
t.name = reader["name"].ToString();
t.nrow = int.Parse(reader["nrow"].ToString());
t.pid = reader["pid"].ToString();
t.havechild = int.Parse(reader["havechild"].ToString());
t.children=new List
list.Add(t);
}
}
catch (SqlException ex)
{
throw ex;
}
}
return assemble(list);
}
///
/// 删除树叶节点
///
public int deleteNode(String nid)
{
int i = 0;
//需要注意的是SQL SERVER数据库好像支持别名和mysql，oracle有点差异
//SQL SERVER错误的写法(貌似sqlserver数据库里区分更新前的和更新后的，下面写法会报错)
//String sql = "update treenode t set t.isdelete=1 where t.nid=@nid and t.isdelete=0 ";
//正确的写法如下：
String sql = "update t set t.isdelete=1 from treenode t where t.nid=@nid and t.isdelete=0 ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
//指定类型，在C#里可以一定程度上避免sql注入问题
SqlParameter p1 = new SqlParameter("@nid",SqlDbType.VarChar);
p1.Value = nid;
command.Parameters.Add(p1);//添加参数
i = command.ExecuteNonQuery();
}
catch (SqlException ex)
{
throw ex;
}
}
return i;
}
///
/// 删除树根节点的查询
///
public List
{
List
if(list1==null)
{
list1 = new List
}
list1.Add(treenode);
if (conns == null)
conns = new SqlConnection(strSqlConn);
String sql = "select t.nid,t.name,t.nrow,t.havechild,t.pid,t.isdelete from treenode t wheret.pid=@pid and t.isdelete=0 ";
using(conns){
try
{
SqlCommand command = new SqlCommand(sql, conns);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@pid",SqlDbType.VarChar );
p1.Value=treenode.nid;
command.Parameters.Add(p1);//添加参数
SqlDataReader reader = command.ExecuteReader();
while(reader.Read()){
TreeNode tt = new TreeNode();
tt.nid = reader["nid"].ToString();
tt.havechild = int.Parse(reader["havechild"].ToString());
list1.Add(tt);
list2.Add(tt);
}
}
catch (SqlException ex)
{
throw ex;
}
for (int i = 0; i < list2.Count;i++ )
{
if(list2[i].havechild==1){
deleteTreeNode(list2[i]);
}
}
}
return list1;
}
///
/// 删除树根的实现方法
///
public int deleteAllNode(TreeNode treenode) {
int sum = 0;
TreeDao tdao=new TreeDao();
List
for (int i = 0; i < oklist.Count;i++ )
{
sum += tdao.deleteNode(oklist[i].nid);
}
return sum;
}
///
/// 修改树节点名称的方法
///
public int updateName(TreeNode treenode) {
int nuber = 0;
String sql = "update t set t.name=@name from treenode t where t.nid=@nid ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@name",SqlDbType.VarChar );
p1.Value=treenode.name;
SqlParameter p2 = new SqlParameter("@nid", SqlDbType.VarChar);
p2.Value=treenode.nid;
command.Parameters.Add(p1);//添加参数
command.Parameters.Add(p2);
nuber= command.ExecuteNonQuery();
}
catch (SqlException ex)
{
throw ex;
}
}
return nuber;
}
///
/// 添加树节点的辅助方法-添加子节点成功后修改父节点的havechild状态（将0修改为1，是1就不修改）
///
public int changeHavechild(TreeNode parentnode) {
int i = 0;
String sql = "update t set t.havechild=1 from treenode t where t.nid=@nid ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@nid",SqlDbType.VarChar );
p1.Value=parentnode.nid;
command.Parameters.Add(p1);//添加参数
i = command.ExecuteNonQuery();
}
catch (SqlException ex)
{
throw ex;
}
}
return i;
}
///
/// 添加树节点的辅助方法-查询那一层次树节点的数量（为了生成节点id-nid，也可以用UUID，太长不建议）
///
public int queryAddNumber(TreeNode parentnode) {
int addn = 0;
String sql = "select count(1) as count from treenode t where t.nrow=@nrow ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@nrow",SqlDbType.Int );
p1.Value=parentnode.nrow;
command.Parameters.Add(p1);//添加参数
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
addn = reader.GetInt32(reader.GetOrdinal("count"));
}
}
catch (SqlException ex)
{
throw ex;
}
}
return addn;
}
///
/// 添加树节点的辅助方法-查询出此父节点的所有信息
///
public TreeNode queryTreeNode(TreeNode treenode) {
TreeNode parentnode = new TreeNode();
String sql = "select t.nid,t.name,t.nrow,t.pid,t.havechild from treenode t wheret.nid=@nid ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@nid",SqlDbType.VarChar);
p1.Value=treenode.nid;
command.Parameters.Add(p1);//添加参数
SqlDataReader reader = command.ExecuteReader();
while (reader.Read())
{
parentnode.nid = reader["nid"].ToString();
parentnode.name = reader["name"].ToString();
parentnode.nrow = int.Parse(reader["nrow"].ToString());
parentnode.havechild = int.Parse(reader["havechild"].ToString());
}
}
catch (SqlException ex)
{
throw ex;
}
}
return parentnode;
}
///
/// 添加树节点方法
///
public int addNode(TreeNode treenode) {
int i = 0;
//通过混合节点（父节点id和新子节点名字name）查找到父节点信息
TreeNode parentnode = queryTreeNode(treenode);
//通过父节点找到子节点所属行的节点数量，以便用于制作子节点nid
int addn = queryAddNumber(parentnode) + 1;//+1是以1开头
//父节点所在行为2，找到3层次节点数量5，组成3-6作为新子节点的nid
String childnid = parentnode.nrow + 1 + "-" + addn;
String sql = "insert into treenode values(@nid,@name,@nrow,@pid,0,0) ";
//using确保资源能被释放//连接数据库
using (SqlConnection conn = new SqlConnection(strSqlConn))
{
try
{
SqlCommand command = new SqlCommand(sql, conn);
command.Connection.Open();
SqlParameter p1 = new SqlParameter("@nid", SqlDbType.VarChar);
p1.Value = childnid;
SqlParameter p2 = new SqlParameter("@name", SqlDbType.VarChar);
p2.Value=treenode.name;
SqlParameter p3 = new SqlParameter("@nrow",SqlDbType.Int );
p3.Value = parentnode.nrow;
SqlParameter p4 = new SqlParameter("@pid",SqlDbType.VarChar );
p4.Value=parentnode.nid;
command.Parameters.Add(p1);//添加参数
command.Parameters.Add(p2);//添加参数
command.Parameters.Add(p3);//添加参数
command.Parameters.Add(p4);//添加参数
i = command.ExecuteNonQuery();
}
catch (SqlException ex)
{
throw ex;
}
}
if (parentnode.havechild==0)
{
i = changeHavechild(parentnode);
}
return i;
}
}