C#端加载数据库，Combobox与Node控件绑定数据源demo示例

最近一直在做网页。用的js比较多，最近需要做一个C#相关的demo，一开始还有点不适应，写了几句有点感觉了

本篇博客的主要内容是C#怎么读取数据库文件里的数据以及相关控件如何绑定数据源，所做的Demo如图所示：

首先在from上将需要控件拖放好，设置属性，连接数据库：

工具--连接到数据库--选择数据源，填写相关数据：

连接数据库之后，在开头引用using System.Data.SqlClient;

编写一个函数，命名为SetCombobox，从数据库内位Combobox绑定数据源，具体的函数如下

      //Combobox绑定数据源
         private void SetCombobox()
         {
             //输入想关联的数据库的基本信息
             SqlConnection conn = new SqlConnection(@" server = DESKTOP-5SDB4D4;Initial Catalog= test;User ID=sa;Password=lmz123LMZ");
             //打开数据库连接
             conn.Open();
             //sql语句
             string str = " select * from [test].[dbo].[TRaw] where c1 = 0";
             //创建命令对象
             SqlCommand lo_cmd = conn.CreateCommand();
             lo_cmd.CommandText = str;
             SqlDataReader dtr = lo_cmd.ExecuteReader();
             while (dtr.Read())
             {
                 //邦定数据
                 comboBox1.Items.AddRange(new object[] { dtr["c3"] });//邦定数据
             }
             dtr.Close();
             comboBox1.SelectedIndex = ;
             conn.Close();
         }

数据库内不同的法律法规有不同的指代编号，这里写一个dictionary函数，当选中法律条款时返回对应的数据编号

  //法律法规与编号相对应
        Dictionary<string, int> laws = new Dictionary<string, int>();

当读取数据库时编写dictionary函数：

  //法律名称
     string Lawsname = (string)dtr["c3"];
     //法律代码
     int number = (int)dtr["c0"];

     //向dictionary函数赋值
      if (!laws.ContainsKey(Lawsname))
         laws.Add(Lawsname, number)
       else
          Console.WriteLine(Lawsname);

点击启动，完成，法律法规已经在列表中显示，且不同的法律法规对应着不同的数列：

在控件右边添加treeview控件，具体绑定数据库代码如下：

 //对应法律名称的法律编号
            int rawid = laws[name];
            int id = ;
            treeView1.Nodes.Clear();

            //输入想关联的数据库的基本信息
            SqlConnection conn = new SqlConnection(@"server = DESKTOP-5SDB4D4;Initial Catalog= test;User ID=sa;Password=lmz123LMZ");
            conn.Open();
            //sql语句
            string str = "select * from [test].[dbo].[TRaw] where c4 = 1 and c0 = " + rawid;
            //创建命令对象
            SqlCommand lo_cmd = conn.CreateCommand();
            lo_cmd.CommandText = str;
            SqlDataReader dtr = lo_cmd.ExecuteReader();

            while (dtr.Read())
            {
                //父节点的内容
                TreeNode node = new TreeNode("第" + NumberToChinese(id) + "条");
                treeView1.Nodes.Add(node);
                //自动展开
                treeView1.ExpandAll();
                string Laws1;

                //法律名称
                if ( !dtr.IsDBNull() )
                {
                    Laws1 = (string)dtr["c3"];
                }
                else
                   Laws1 = "子条款";
                node.Tag = Laws1;
                id++;

            }
            dtr.Close();
            conn.Close();

编辑nodeMouseClick事件：

 private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            label1.Text = e.Node.Tag.ToString();
        }

效果如图所示，不同法律名称对应不同的数据量，单机node显示不同的法律条文：

Demo完整代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using DevComponents.DotNetBar;
using System.Data.SqlClient;

namespace WindowsFormsApp1
{
    public partial class Form1 :Form
    {
        //法律法规与编号相对应
        Dictionary<string, int> laws = new Dictionary<string, int>();

        public Form1()
        {
            InitializeComponent();
            SetInfo();
            SetCombobox();
        }

        //设置属性信息
        private void SetInfo()
        {
            //获取窗体长度
            int width = this.Width;
            //获取窗体高度
            int height = this.Height;

            //设置panel1的属性
            panel1.Height = height / ;
            panel1.Top = ;
            panel1.Left = ;
            panel1.Width = width;

            //设置panel2的属性
            panel2.Height = height - height / ;
            panel2.Top = panel1.Height;
            panel2.Left = ;
            panel2.Width = width / ;

            //设置panel3的属性
            panel3.Height = height - height / ;
            panel3.Top = panel1.Height;
            panel3.Left = width / ;
            panel3.Width = width - width / ;

            //设置treeView1属性
            treeView1.Top = ;
            treeView1.Left = ;
            treeView1.Width = panel2.Width;
            treeView1.Height = panel2.Height;
        }

        //Combobox绑定数据源
        private void SetCombobox()
        {
            //输入想关联的数据库的基本信息
            SqlConnection conn = new SqlConnection(@"server = DESKTOP-5SDB4D4;Initial Catalog= test;User ID=sa;Password=lmz123LMZ");
            //打开数据库连接
            conn.Open();
            //sql语句
            string str = " select * from [test].[dbo].[TRaw] where c1 = 0";
            //创建命令对象
            SqlCommand lo_cmd = conn.CreateCommand();
            lo_cmd.CommandText = str;
            SqlDataReader dtr = lo_cmd.ExecuteReader();

            while (dtr.Read())
            {
                //邦定数据
                comboBox1.Items.AddRange(new object[] { dtr["c3"] });//邦定数据
                //法律名称
                string Lawsname = (string)dtr["c3"];
                //法律代码
                int number = (int)dtr["c0"];

                //向dictionary函数赋值
                if (!laws.ContainsKey(Lawsname))
                    laws.Add(Lawsname, number);
                else
                    Console.WriteLine(Lawsname);
            }
            dtr.Close();
            comboBox1.SelectedIndex = ;
            conn.Close();
        }

        //显示具体的法律条款
        private void ShowLaw(string name)
        {
            //对应法律名称的法律编号
            int rawid = laws[name];
            int id = ;
            treeView1.Nodes.Clear();

            //输入想关联的数据库的基本信息
            SqlConnection conn = new SqlConnection(@"server = DESKTOP-5SDB4D4;Initial Catalog= test;User ID=sa;Password=lmz123LMZ");
            conn.Open();
            //sql语句
            string str = "select * from [test].[dbo].[TRaw] where c4 = 1 and c0 = " + rawid;
            //创建命令对象
            SqlCommand lo_cmd = conn.CreateCommand();
            lo_cmd.CommandText = str;
            SqlDataReader dtr = lo_cmd.ExecuteReader();

            while (dtr.Read())
            {
                //父节点的内容
                TreeNode node = new TreeNode("第" + NumberToChinese(id) + "条");
                treeView1.Nodes.Add(node);
                //自动展开
                treeView1.ExpandAll();
                string Laws1;

                //法律名称
                if ( !dtr.IsDBNull() )
                {
                    Laws1 = (string)dtr["c3"];
                }
                else
                   Laws1 = "子条款";
                node.Tag = Laws1;
                id++;

            }
            dtr.Close();
            conn.Close();
        }

        //当选择框发生变化时
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            string name = (string)comboBox1.SelectedItem;
            ShowLaw(name);
        }

        //数字转中文
        public string NumberToChinese(int number)
        {
            string res;
            string str = number.ToString();
            string schar = str.Substring(, );
            switch (schar)
            {
                case "":
                    res = "一";
                    break;
                case "":
                    res = "二";
                    break;
                case "":
                    res = "三";
                    break;
                case "":
                    res = "四";
                    break;
                case "":
                    res = "五";
                    break;
                case "":
                    res = "六";
                    break;
                case "":
                    res = "七";
                    break;
                case "":
                    res = "八";
                    break;
                case "":
                    res = "九";
                    break;
                default:
                    res = "零";
                    break;
            }
            if (str.Length > )
            {
                switch (str.Length)
                {
                    case :
                    case :
                        res += "十";
                        break;
                    case :
                    case :
                        res += "百";
                        break;
                    case :
                        res += "千";
                        break;
                    case :
                        res += "万";
                        break;
                    default:
                        res += "";
                        break;
                }
                res += NumberToChinese(int.Parse(str.Substring(, str.Length - )));
            }

            res = res.Replace("十零", "十").Replace("一十", "十");
            return res;
        }

        private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            label1.Text = e.Node.Tag.ToString();
        }

    }
}