C# 增删改查 实例

本次实现的是visual studio 的窗体应用程序+sql server的增删改查操作。

1.首先看一下数据库的表结构，比较简单，只有一个表

2.看一下项目的目录，只有标注的三个文件是需要修改的。

3.然后看一下界面的实现，只有以下两个界面，Form1这个界面的上半部分是一个ToolStrip,下面的部分是DataGridView。Edit界面就是一些label,textBox以及button的组合，直接通过拖拽建议相应的界面即可。建立完页面后注意要修改相应插件的名称，就如第三张图所示，第三张图对应的是第一张图的DataGridView的名称。其他的插件的名称可以在源代码中找对应的，比较容易。

 4.具体代码实现

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

namespace zengshangaicha
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        DataSet ds = new DataSet();
        //获取数据方法
        private void GetDB()
        {
           
            ds = new DataSet();
            DBhelper dbhelper = new DBhelper();
            try
            {
                string sql = @"Select Sno 学号,Sname 姓名,Sclass 班级,SChinese 语文,SMath 数学,SEnglish 英语,SChinese+SMath+SEnglish 总分,
                                  (SChinese+SMath+SEnglish)/3 平均分 from Score order by SChinese+SMath+SEnglish desc";
                SqlDataAdapter adapter = new SqlDataAdapter(sql, dbhelper.Connection);
                adapter.Fill(ds, "Score");
                this.dgv.DataSource = this.ds.Tables["Score"];
            }
            catch (Exception)
            {

                MessageBox.Show("数据库操作错误", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }

        //退出按钮被点击
        private void tsbtnExit_Click(object sender, EventArgs e)
        {
            this.Close();
        }
        //窗体加载事件
        private void Form1_Load(object sender, EventArgs e)
        {
            GetDB();
        }
        //添加按钮被点击
        private void tsbtnIn_Click(object sender, EventArgs e)
        {
            Edit ed = new Edit();
            ed.ShowDialog();
            GetDB();
        }
        //修改按钮被点击
        private void tsbtnUpdate_Click(object sender, EventArgs e)
        {
            Edit ed = new Edit();
            ed.Sno = Convert.ToInt32(this.dgv.SelectedCells[0].Value);
            ed.ShowDialog();
            GetDB();
        }
        //删除按钮被点击
        private void tsbtnDelete_Click(object sender, EventArgs e)
        {
            Delete();
        }
        //删除方法
        private void Delete()
        {

            if (this.dgv.CurrentRow != null)
            {
                DialogResult dr = MessageBox.Show("确定要删除：" + dgv.CurrentRow.Cells[1].Value + "相关成绩信息", "系统提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
                if (dr == DialogResult.OK)
                {
                    DBhelper helper = new DBhelper();
                    try
                    {
                        //sql语句
                        StringBuilder sb = new StringBuilder();
                        sb.AppendFormat("delete from Score where Sno={0}", Convert.ToInt32(dgv.CurrentRow.Cells[0].Value));
                        //执行工具
                        SqlCommand cmd = new SqlCommand(sb.ToString(), helper.Connection);
                        //打开数据库连接
                        helper.OpenConnection();
                        //执行
                        int result = cmd.ExecuteNonQuery();
                        if (result == 1)
                        {
                            MessageBox.Show("删除成功", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                            //重新绑定dgv
                            this.GetDB();
                        }
                    }
                    catch (Exception)
                    {

                        MessageBox.Show("数据库操作失败", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                    finally
                    {
                        helper.CloseConnection();
                    }
                }
            }

        }
        //查询按钮被点击
        private void toolStripButton1_Click(object sender, EventArgs e)
        {
            this.Search();
        }     //查询方法
        private void Search()
        {
            ds = new DataSet();
            DBhelper dbHelper = new DBhelper();
            try
            {
                string strSql = @"Select Sno 学号,Sname 姓名,Sclass 班级,SChinese 语文,SMath 数学,SEnglish 英语,SChinese+SMath+SEnglish 总分,
                                  (SChinese+SMath+SEnglish)/3 平均分 from Score
                                 where 1=1";
                if (toolStripTextBox1.Text.Trim() != null && toolStripTextBox1.Text.Trim().Length > 0)
                {
                    strSql += " and Sname like '%" + toolStripTextBox1.Text.Trim() + "%'";
                }
                if (toolStripTextBox2.Text.Trim() != null && toolStripTextBox2.Text.Trim().Length > 0)
                {
                    strSql += " and Sclass like '%" + toolStripTextBox2.Text.Trim() + "%'";
                }
                strSql += "order by SChinese+SMath+SEnglish desc";
                SqlDataAdapter adapter = new SqlDataAdapter(strSql, dbHelper.Connection);
                adapter.Fill(ds, "score");
                this.dgv.DataSource = this.ds.Tables["score"];
            }
            catch (Exception)
            {
                MessageBox.Show("数据库操作错误！", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }

        
    }
}

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

namespace zengshangaicha
{
    public partial class Edit : Form
    {
        public int Sno = -1;
        DataSet ds = new DataSet();
        public Edit()
        {
            InitializeComponent();
        }
        //窗体加载
        private void Edit_Load(object sender, EventArgs e)
        {
            if (Sno == -1)//没有被选定的行数
            {

            }
            else//修改
            {
                GetInfo();
                this.btnSave.Text = "修改";
            }
        }
        //保存按钮
        private void btnSave_Click(object sender, EventArgs e)
        {
            if (CheckItem())
            {
                if (this.Sno == -1)//新增
                {
                    if (CheckSnoExit())
                    {
                        InsertDB();
                    }
                }
                else//更新
                {
                    UpdateScore();
                }
            }
        }
        //非空验证
        private bool CheckItem()
        {
            bool checkValue = true;
            if (this.textBox1.Text.Trim().Length == 0)
            {
                MessageBox.Show("学号不能为空", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                checkValue = false;
                this.textBox1.Text = " ";
            }
            return checkValue;
        }
        //增加方法
        //查重
        private bool CheckSnoExit()
        {
            bool exit = true;
            DBhelper dbhelper = new DBhelper();
            try
            {
                StringBuilder sb = new StringBuilder();
                sb.AppendFormat("select * from Score where Sno='{0}'", textBox1.Text.Trim());
                SqlCommand cmd = new SqlCommand(sb.ToString(), dbhelper.Connection);
                dbhelper.OpenConnection();
                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.Read())
                {
                    MessageBox.Show("该学号已存在", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    exit = false;
                }
                reader.Close();
            }
            catch (Exception)
            {
                MessageBox.Show("数据库操作错误", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            finally
            {
                dbhelper.CloseConnection();
            }
            return exit;
        }
        //执行增加
        private void InsertDB()
        {
            DBhelper helper = new DBhelper();
            try
            {
                //SQL语句
                StringBuilder sb = new StringBuilder();
                sb.AppendLine("insert into Score");
                sb.AppendFormat("values('{0}','{1}','{2}','{3}','{4}','{5}')", textBox1.Text.Trim(), textBox2.Text.Trim(), comboBox1.Text.Trim(), textBox4.Text.Trim(), textBox5.Text.Trim(), textBox6.Text.Trim());
                //执行工具
                SqlCommand cmd = new SqlCommand(sb.ToString(), helper.Connection);
                //打开连接
                helper.OpenConnection();
                //执行
                int result = cmd.ExecuteNonQuery();
                if (result > 0)
                {
                    MessageBox.Show("添加成功", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.Close();
                }
            }
            catch (Exception)
            {
                MessageBox.Show("添加数据库操作错误", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            finally
            {
                helper.CloseConnection();
            }
        }

        //通过ID查找类别
        private void GetInfo()
        {
            DBhelper dbhelper = new DBhelper();
            try
            {
                //SQL语句
                StringBuilder sb = new StringBuilder();
                sb.AppendLine("select Sno,Sname,Sclass,SChinese,SMath,SEnglish");
                sb.AppendLine("from Score");
                sb.AppendFormat("where Sno={0}", Sno);
                //执行工具
                SqlCommand cmd = new SqlCommand(sb.ToString(), dbhelper.Connection);
                //打开连接
                dbhelper.OpenConnection();
                //执行
                SqlDataReader reader = cmd.ExecuteReader();
                if (reader.Read())
                {
                    textBox1.Text = reader["Sno"].ToString();
                    textBox2.Text = reader["Sname"].ToString();
                    comboBox1.Text = reader["Sclass"].ToString();
                    textBox4.Text = reader["SChinese"].ToString();
                    textBox5.Text = reader["SMath"].ToString();
                    textBox6.Text = reader["SEnglish"].ToString();
                }
                reader.Close();
            }
            catch (Exception)
            {
                MessageBox.Show("操作错误", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            finally
            {
                dbhelper.CloseConnection();
            }

        }
        //修改
        private void UpdateScore()
        {
            DBhelper helper = new DBhelper();
            try
            {
                StringBuilder sql = new StringBuilder();
                //修改数据库语句
                sql.AppendLine("update Score");
                sql.AppendFormat("set Sname='{0}',Sclass='{1}',SChinese='{2}',SMath='{3}',SEnglish='{4}'", textBox2.Text.Trim(), comboBox1.Text.Trim(), textBox4.Text.Trim(), textBox5.Text.Trim(), textBox6.Text.Trim());
                sql.AppendFormat("where Sno={0}", Sno);
                //执行工具
                SqlCommand cmd = new SqlCommand(sql.ToString(), helper.Connection);
                //打开数据库连接
                helper.OpenConnection();
                //执行
                int result = cmd.ExecuteNonQuery();
                //判断
                if (result == 1)
                {

                    MessageBox.Show("修改成功", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.Close();
                }
                else
                {

                    MessageBox.Show("修改失败", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            catch (Exception)
            {

                MessageBox.Show("修改数据库操作错误", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            finally
            {
                helper.CloseConnection();
            }

        }
        //取消按钮
        private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }

       
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms;

namespace zengshangaicha
{
    class DBhelper
    {
       
        private string connString = "server=.;database=student1;user=sa;pwd=000000;";//连接数据库自己的用户名密码
        private SqlConnection connection;

        public SqlConnection Connection
        {
            get
            {
                if (connection == null)
                {
                   
                    connection = new SqlConnection(connString);
                }
                return connection;
            }

        }
        //打开数据库连接
        public void OpenConnection()
        {
            if (Connection.State == ConnectionState.Closed)
            {
               
                Connection.Open();
            }
            else if (Connection.State == ConnectionState.Broken)
            {
                Connection.Close();
                Connection.Open();
            }
        }
        //关闭数据库
        public void CloseConnection()
        {
            if (Connection.State == ConnectionState.Open || Connection.State == ConnectionState.Broken)
            {
                Connection.Close();
            }
        }
    }
}

4.在复制代码的时候，需要注意的是，在下面这张图里面的点击事件是不会自动添加的，需要自己手动写一下，具体格式如第二张图所示。

至此，增删改查完毕。

以下是原文链接：https://www.cnblogs.com/qq1793033075/p/12188268.html