【2019-2020春学期】数据库实验3：CRUD 学习增、删、改、查操作
实验目的：
学习增、删、改、查操作。
实验内容：
学习增删改查操作
目标效果：
实验步骤：
1、数据库数据准备：
需要在数据库里准备一张表，以便下面可以进行使用
2、创建新项目：
3、根据目标效果从工具箱添加控件：
（1）添加”DataGridView“，并且连接数据（具体步骤参考：数据库实验2）
（2）添加控件：
4、设置“增”按钮的点击事件：
private void Insert_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String StuName = textBox2.Text.Trim();
String StuSex = textBox3.Text.Trim();
String StuAge = textBox4.Text.Trim();
String StuSdept = textBox5.Text.Trim();
try
{
con.Open();
string insertStr = "INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept) " +
"VALUES('" + StuID + "','" + StuName + "','" + StuSex + "'," + StuAge + ",'" + StuSdept + "')";
SqlCommand cmd = new SqlCommand(insertStr, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("输入数据违反要求");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
注意事项：
string insertStr = "INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept) " +
"VALUES(" + StuID + "," + StuName + "," + StuSex + "," + StuAge + "," + StuSdept + ")";
这么写是错误的，等价的SQL语句为：
INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept) VALUES(201215134,秦修,男,23,FM)
和数据库里定义的属性是不相符合的，要根据属性的要求添加单引号。
5、设置“删”的点击事件：
private void Delete_Click(object sender, EventArgs e)
{
try
{
con.Open();
string select_id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();//选择的当前行第一列的值，也就是ID
string delete_by_id = "delete from Student where Sno=" + select_id;//sql删除语句
SqlCommand cmd = new SqlCommand(delete_by_id, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("请正确选择行!");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
注意事项：
在进行删除测试的时候，选择的数据有要求。由于在我的数据库中，有些数据和在另一张中也使用到了，这时候如果进行删除操作，是不能实现的。
6、设置“改”的点击事件：
private void Update_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String StuName = textBox2.Text.Trim();
try
{
con.Open();
string insertStr = "UPDATE Student SET Sname = '" + StuName + "' WHERE Sno = '" + StuID + "'";
SqlCommand cmd = new SqlCommand(insertStr, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("输入数据违反要求!");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
7、设置“查”的点击事件：
private void Select_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String conn = "Data Source=.;Initial Catalog=SCHOOL;User ID=sa;Password=********";
SqlConnection sqlConnection = new SqlConnection(conn);
try
{
sqlConnection.Open();
String select_by_id = "select * from Student where Sno='" + StuID + "'";
SqlCommand sqlCommand = new SqlCommand(select_by_id,sqlConnection);
SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
BindingSource bindingSource = new BindingSource();
bindingSource.DataSource = sqlDataReader;
dataGridView1.DataSource = bindingSource;
}
catch
{
MessageBox.Show("查询语句有误！");
}
finally
{
sqlConnection.Close();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
8、设置“Close”的点击事件
private void Close_Click(object sender, EventArgs e)
{
Application.Exit();
}
运行效果：
（1）增加数据
增加数据失败：
（2）删除数据
未正确选择行时：
（3）修改数据
（4）查询数据
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 CRUD
{
public partial class Form1 : Form
{
SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=SCHOOL;User ID=sa;Password=*********");
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
// TODO: 这行代码将数据加载到表“sCHOOLDataSet.Student”中。您可以根据需要移动或删除它。
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
private void Insert_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String StuName = textBox2.Text.Trim();
String StuSex = textBox3.Text.Trim();
String StuAge = textBox4.Text.Trim();
String StuSdept = textBox5.Text.Trim();
try
{
con.Open();
string insertStr = "INSERT INTO Student(Sno,Sname,Ssex,Sage,Sdept) " +
"VALUES('" + StuID + "','" + StuName + "','" + StuSex + "'," + StuAge + ",'" + StuSdept + "')";
SqlCommand cmd = new SqlCommand(insertStr, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("输入数据违反要求");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
private void Close_Click(object sender, EventArgs e)
{
Application.Exit();
}
private void Delete_Click(object sender, EventArgs e)
{
try
{
con.Open();
string select_id = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();//选择的当前行第一列的值，也就是ID
string delete_by_id = "delete from Student where Sno=" + select_id;//sql删除语句
SqlCommand cmd = new SqlCommand(delete_by_id, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("请正确选择行!");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
private void Update_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String StuName = textBox2.Text.Trim();
try
{
con.Open();
string insertStr = "UPDATE Student SET Sname = '" + StuName + "' WHERE Sno = '" + StuID + "'";
SqlCommand cmd = new SqlCommand(insertStr, con);
cmd.ExecuteNonQuery();
}
catch
{
MessageBox.Show("输入数据违反要求!");
}
finally
{
con.Dispose();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
private void Select_Click(object sender, EventArgs e)
{
String StuID = textBox1.Text.Trim();
String conn = "Data Source=.;Initial Catalog=SCHOOL;User ID=sa;Password=************";
SqlConnection sqlConnection = new SqlConnection(conn);
try
{
sqlConnection.Open();
String select_by_id = "select * from Student where Sno='" + StuID + "'";
SqlCommand sqlCommand = new SqlCommand(select_by_id,sqlConnection);
SqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
BindingSource bindingSource = new BindingSource();
bindingSource.DataSource = sqlDataReader;
dataGridView1.DataSource = bindingSource;
}
catch
{
MessageBox.Show("查询语句有误！");
}
finally
{
sqlConnection.Close();
}
this.studentTableAdapter.Fill(this.sCHOOLDataSet.Student);
}
}
}
心得：
并不是很顺利，踩了一些坑