实验反馈3——数据的增删改查

原創

weixin_45871977

2020-05-18 07:26

本周学习了怎样在DataGridView上面对数据进行增删改查，增删改的操作基本相同，查询的操作略有不同，需要将查询的值赋给数据源，之后数据源再赋给DataGridView.
注意：对于一些变量可以设置为全局变量，如连接数据库时的变量写为全局变量，这样在修改连接的数据库时会方便很多。

这里的修改是根据学号修改姓名，可以根据实际需要进行其他操作；查询是通过学号查询；在增加信息时应该对年龄、性别的输入作具体的要求，如年龄>0，性别只能为“男”或“女”，在接下来的实验中应该做具体的要求。

代码：

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 CURD1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: 这行代码将数据加载到表“studentDataSet.Student”中。您可以根据需要移动或删除它。
            this.studentTableAdapter.Fill(this.studentDataSet.Student);
        }
        SqlConnection con = new SqlConnection("Data Source =.; Initial Catalog = Student;  Persist Security Info = True;User ID = sa; Password = 123"); //连接数据库
        private void buttonadd_Click(object sender, EventArgs e)//增加
        {
            string StuSno = textBoxsno.Text.Trim();
            string StuSname = textBoxsname.Text.Trim();
            string StuSsex = textBoxssex.Text.Trim();
            string StuSage = textBoxsage.Text.Trim();
            string StuSdept = textBoxsdept.Text.Trim();
            //SqlConnection con = new SqlConnection("Data Source =.; Initial Catalog = Student;  Persist Security Info = True;User ID = sa; Password = 123"); //连接数据库
            try
            {
                con.Open();     //打开数据库
                string insertStr = "INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept)" + "VALUES('" + StuSno + "','" + StuSname + "','" + StuSsex + "'," + StuSage + ",'" + StuSdept + "')";
                SqlCommand cmd = new SqlCommand(insertStr, con);
                cmd.ExecuteNonQuery();      //将增加后的信息直接出来
            }
            catch
            {
                MessageBox.Show("输入数据违法要求！");
            }
            finally
            {
                con.Dispose();      //关闭数据库
            }
            this.studentTableAdapter.Fill(this.studentDataSet.Student);
        }
        private void buttondelete_Click(object sender, EventArgs e)//删除
        {                 
            try
            {
                con.Open();     //打开数据库
                string select_Sno = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();//选择的当前行第一列的值，也就是Sno
                string delete_by_Sno = "DELETE FROM Student WHERE Sno='" + select_Sno+"'";//sql删除语句
                SqlCommand cmd = new SqlCommand(delete_by_Sno, con);
                cmd.ExecuteNonQuery();      //将增加后的信息直接出来
            }
            catch
            {
                MessageBox.Show("请选择正确行！");
            }
            finally
            {
                con.Dispose();      //关闭数据库
            }
            this.studentTableAdapter.Fill(this.studentDataSet.Student);
        }
        private void buttonupdate_Click(object sender, EventArgs e)//修改，根据学号修改姓名
        {
            string StuSno = textBoxsno.Text.Trim();
            string StuSname = textBoxsname.Text.Trim();
            try
            {
                con.Open();     //打开数据库
                string update_sname = "UPDATE Student SET Sname='" + StuSname + "'WHERE Sno='" + StuSno+"'";
                SqlCommand cmd = new SqlCommand(update_sname ,con);
                cmd.ExecuteNonQuery();      //将增加后的信息直接出来
            }
            catch
            {
                MessageBox.Show("输入数据违反要求");
            }
            finally
            {
                con.Dispose();      //关闭数据库
            }
            this.studentTableAdapter.Fill(this.studentDataSet.Student);
        }
        private void buttonselect_Click(object sender, EventArgs e)//查找,根据学号查找
        {
            string StuSno = textBoxsno.Text.Trim();
            String conn = "Data Source =.; Initial Catalog = Student;  Persist Security Info = True;User ID = sa; Password = 123";
            SqlConnection sqlconnection = new SqlConnection(conn);//实例化连接对象
            try
            {
                sqlconnection.Open();
                String select_by_sno = "select * from Student where Sno='" + StuSno + "'";
                SqlCommand sqlcommand = new SqlCommand(select_by_sno, sqlconnection);
                SqlDataReader sqldatareader = sqlcommand.ExecuteReader();
                BindingSource bindingsource = new BindingSource();
                bindingsource.DataSource = sqldatareader;
                dataGridView1.DataSource = bindingsource;
                //将读出来的值赋给数据源，再将数据源给dataGridView
            }
            catch
            {
                MessageBox.Show("查询语句有误，请认真检查SQL语句");
            }
            finally
            {
                sqlconnection.Close();
            }
        }
        private void buttonclose_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
    }