学生信息管理系统，数据库和C#链接，查询，删除，增加，修改----C#

谁践踏了优雅 2023-02-18 12:58 14阅读 0赞

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//vs与数据库建立连接的过程：
    //与数据库建立起连接（建立Connection类的实例对象）
    //打开连接（Connection实例对象的Open()方法）
    //执行操作数据库命令（对应SqlCommand）
    //关闭数据库连接
    
    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 System.Data.SqlClient;
    using System.Runtime.CompilerServices;
    
    namespace 学生页面选课系统
    {
        public partial class Form1 : Form
        {
            public Form1()
            {
                InitializeComponent();
            }
            private void button1_Click(object sender, EventArgs e)
            {
                try
                {
                    string strcon = DataConn.con;
                    //通过类名直接调用静态成员变量
                    SqlConnection conn = new SqlConnection(strcon);
                    //给数据库建立连接
                    conn.Open();
                    //查询用sq1语句，数据库连接
                    string strsq1 = " select Snum as 学生学号,Sname as 学生姓名,Sage as 学生年龄,Ssex as 学生性别 ,Sdept as 所属院系 from Table_student";
                    //填充数据集
                    //创建SqlDataAdapter对象
                    SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(strsq1, conn);
                    //填充DataSet
                    DataSet dataset = new DataSet();
                    sqlDataAdapter.Fill(dataset, "Table_student");
                    //将数据表格在dataGridView中展示
                    dataGridView1.DataSource = dataset.Tables["Table_student"];
                    conn.Close();
                }
                catch (Exception mess)
                {
                    MessageBox.Show("出现异常!", mess.Message);
                }           
            }
    
            private void button2_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "")
                {
                    MessageBox.Show("查询学号不能为空！");
                }
                else
                {
                    try
                    {
                        string strcon = DataConn.con;
                        //通过类名直接调用静态成员变量
                        SqlConnection conn = new SqlConnection(strcon);
                        //给数据库建立连接
                        conn.Open();
                        //查询用sq1语句，数据库连接
                        string strsq1 = " select Snum as 学生学号,Sname as 学生姓名,Sage as 学生年龄,Ssex as 学生性别 ,Sdept as 所属院系 from Table_student where Snum='" + textBox1.Text + "'";
                        MessageBox.Show(strcon);
                        //填充数据集
                        //创建SqlDataAdapter对象
                        SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(strsq1, conn);
                        //填充DataSet
                        DataSet dataset = new DataSet();
                        sqlDataAdapter.Fill(dataset, "Table_student");
                        //将数据表格在dataGridView中展示
                        if (dataset.Tables["Table_student"].Rows.Count == 0)
                        {
                            MessageBox.Show("您输入的学号有误！");
                        }
                        else
                        {
                            dataGridView1.DataSource = dataset.Tables["Table_student"];
                        }
                        conn.Close();
                    }
                    catch (Exception mess)
                    {
                        MessageBox.Show("出现异常!", mess.Message);
                    }
                }
            }
    
            private void button3_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "" || textBox4.Text == "" || comboBox1.SelectedItem.ToString () == "") 
                {
                    MessageBox.Show("学生信息不能有空选项！");
                }
                else
                {
                    try
                    {
                        string strcon = DataConn.con;
                        //通过类名直接调用静态成员变量
                        SqlConnection conn = new SqlConnection(strcon);
                        //给数据库建立连接
                        conn.Open();
                        //查询用sq1语句，数据库连接
                        string strsq1 = "insert into Table_student values ('" + textBox1.Text.Trim() + "','" + textBox2.Text .Trim ()+ "','" + textBox3.Text.Trim() + "','" + comboBox1.Text.Trim()  + "','" + textBox4.Text .Trim ()+ "')";
                        MessageBox.Show(strcon);
                        //创建一个可以与数据源直接进行通信的command对象                                  
                        SqlCommand sqlCommand = new SqlCommand(strsq1 ,conn);                                   
                        //返回insert delete  updata 所影响的数据行数
                       int result= sqlCommand.ExecuteNonQuery();
                        if(result>0)
                        {
                            MessageBox.Show("成功添加数据！");
                        }
                        else
                        {
                            MessageBox.Show("添加数据失败！");
                        }
                        button1_Click(this,e);
                        conn.Close();
                    }
                    catch (Exception mess)
                    {
                        MessageBox.Show(mess.Message,"出现异常!");
                    }
                }
            }
            private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
            {
                int n = dataGridView1.CurrentCell.RowIndex;
                textBox1.Text = dataGridView1[0, n].Value.ToString();
                textBox2.Text = dataGridView1[1, n].Value.ToString();
                textBox3.Text = dataGridView1[2, n].Value.ToString();
                comboBox1.Text = dataGridView1[3, n].Value.ToString();
                textBox4.Text = dataGridView1[4, n].Value.ToString();
            }
            private void button4_Click(object sender, EventArgs e)
            {
                try
                {
                    string strcon = DataConn.con;
                    //通过类名直接调用静态成员变量
                    SqlConnection conn = new SqlConnection(strcon);
                    //给数据库建立连接
                    conn.Open();
                    //查询用sq1语句，数据库连接
                    string strsq1 = "update Table_student set Sname='" + textBox2.Text.Trim() + "',Sage=" + textBox3.Text.Trim() + ",Ssex='" + comboBox1.Text.Trim() + "',Sdept='" + textBox4.Text.Trim() + "' where  Snum='"+textBox1 .Text .Trim () +"' " ;
                    MessageBox.Show(strcon);
                    //创建一个可以与数据源直接进行通信的command对象                              
                    SqlCommand sqlCommand = new SqlCommand(strsq1, conn);                                  
                    //返回insert delete  updata 所影响的数据行数
                    int result = sqlCommand.ExecuteNonQuery();
                    if (result > 0)
                    {
                        MessageBox.Show("成功修改数据！");
                    }
                    else
                    {
                        MessageBox.Show("修改数据失败！");
                    }
                    button1_Click(this, e);
                    conn.Close();
                }
                catch (Exception mess)
                {
                    MessageBox.Show(mess.Message, "出现异常!");
                }
            }
            private void button5_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "")
                {
                    MessageBox.Show("查询学号不能为空！");
                }
                else
                {
                    try
                    {
                        string strcon = DataConn.con;
                        //通过类名直接调用静态成员变量
                        SqlConnection conn = new SqlConnection(strcon);
                        //给数据库建立连接
                        conn.Open();
                        //弹出是否确认删除的对话框
                        DialogResult result = MessageBox.Show("确认退出吗?", "操作提示", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
                        if (result == DialogResult.OK)
                        {
                            //查询用sq1语句，数据库连接
                            string strsq1 = "delete from Table_student where Snum='" + textBox1.Text.Trim() + "'  ";
                            MessageBox.Show(strcon);
                            //创建一个可以与数据源直接进行通信的command对象                              
                            SqlCommand sqlCommand = new SqlCommand(strsq1, conn);
                            //返回insert delete  updata 所影响的数据行数
                            int resultnum = sqlCommand.ExecuteNonQuery();
                            if (resultnum > 0)
                            {
                                MessageBox.Show("成功删除数据！");
                            }
                            else
                            {
                                MessageBox.Show("删除数据失败！");
                            }
                            button1_Click(this, e);
                            conn.Close();
                        }                
                    }
                    catch (Exception mess)
                    {
                        MessageBox.Show(mess.Message, "出现异常!");
                    }
                }
            }
        }
    }

using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    using System.Data.SqlClient;
    
    
    namespace 学生页面选课系统
    {
        class DataConn
        {
            //创建一个公共类，在类中通过静态变量或者静态方法的形式设置连接字符串
            //定义静态成员变量
            public static string con = "server=.;database=master;integrated security=true;";
        }
    }

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