winform 连接数据库

其实很简单，复制即用

这个需要引入mysql的组件，直接把代码复制进去，ALT+回车导包就行了
一定要注意，是引入，不是重新生成方法

完整代码

using System;
using System.Windows.Forms;
using MySql.Data.MySqlClient;//你的项目名
namespace TextWinform1
{class JDBC //类 文件名{//方法public static int getUser(string username, string pwd){MySqlConnection sqlCnn = new MySqlConnection();sqlCnn.ConnectionString = //         数据地址            用户名             密码             使用的数据库名"server = '39.1.8.2'; uid = 'diandian'; pwd = '2123'; database = 'diandian';Charset=utf8";//连接字符串MySqlCommand sqlCmd = new MySqlCommand();sqlCmd.Connection = sqlCnn;sqlCmd.CommandText = // sql 语句"select * from user where username ='" + username + "' and pwd ='" + pwd + "'";try{//连接sqlCnn.Open();MySqlDataReader rec = sqlCmd.ExecuteReader();//判断 返回值为空if (!rec.Read()){MessageBox.Show("不对");return 0;}MessageBox.Show(pwd);MessageBox.Show(username);//这里我是查用户是一条数据，如果是多条 就需要循环来接受/*while (rec.Read()){user.uid = rec.GetInt32(0);user.username = rec.GetString(1);}*/}catch (Exception ex){MessageBox.Show(ex.Message, "error");}finally{//关闭连接sqlCnn.Close();}return 1;}}
}

调用

		private void login_Click(object sender, EventArgs e){int type = JDBC.getUser(usernametext.Text,passwordtext.Text);//判断 是否登录成功if(type == 0){usernametext.Text = "";passwordtext.Text = "";}else if(type == 1){//成功就 new下一个页面  这里可以看我之前跳转页面的博客this.DialogResult = DialogResult.OK;}}

winform 登录跳转页面 https://blog.csdn.net/qq_45777315/article/details/108637549

第二种

using MySql.Data.MySqlClient;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;namespace Code
{class MysqlConnl{public static List<dept> goMysql(string id){#region MySQL操作//读取数据库操作// MessageBox.Show("链接数据库操作");string constring = "data source=39.106.212.00;database=medical_waste;user id=medical;password=root;pooling=true;charset=utf8;";List<dept> list = new List<dept>();using (MySqlConnection msc = new MySqlConnection(constring)){//写入sql语句string sql = "SELECT m.id,d.`name` AS dname,w.`name` AS wname FROM dept_medical_waste_type_dict m LEFT JOIN dept_dict d ON d.`code`=m.`dept_code` LEFT JOIN medical_waste_type_dict w ON w.`code`=m.`medical_waste_type_code` WHERE d.`id`=" + id;//创建命令对象MySqlCommand cmd = new MySqlCommand(sql, msc);try{//打开数据库连接msc.Open();//执行命令,ExcuteReader返回的是DataReader对象MySqlDataReader reader = cmd.ExecuteReader();Console.WriteLine(reader);//循环单行读取数据，当读取为null时，就退出循环while (reader.Read()){dept d = new dept();d.id = reader["id"].ToString();d.dname = reader["dname"].ToString();d.wname = reader["wname"].ToString();list.Add(d);//Console.WriteLine("进入循环\t");//输出第一列字段值Trace.Write("trace"+reader["id"] + "\n");Trace.Write("trace"+reader["dname"] + "\n");Console.Write("console"+reader["id"] + "\t");//判断字段"username"是否为null，为null数据转换会失败/*if (!reader.IsDBNull(1)){//输出第二列字段值Console.Write(reader.GetString(1) + "\t");//Console.Write(reader.GetString("username") + "\t");}*/}}catch (MySqlException ex){switch (ex.Number){case 0:Console.WriteLine("无法连接到服务器。");break;case 1045:Console.WriteLine("用户名/密码无效，请重试");break;default:Console.WriteLine(ex);break;}}return list;}#endregion// Console.ReadKey();}}
}

第三种

				 //sql语句string updNews = string.Format("UPDATE pdf_news SET index_title={0}," +"title={1}," +"sub_standard={2}," +"author={3}," +"content={4} WHERE id={5}", indexTxt.Text,titleTxt.Text, subStandardTxt.Text,authorTxt.Text, contentRich.Text,Config.id);//执行sqlint news = MySqlHelper.ExecuteNonQuery("server=39.127.0.0;user=shuzi;password=shuzi;database=shuzibao;Charset=utf8", updNews, null);

第四种

string sql = "SELECT l.lssue_number,l.publication_date,n.anchor_area,v.version_number,"+"n.index_title,n.sub_standard,n.title,n.author,n.content FROM pdf_news n "+"LEFT JOIN pdf_version v ON n.pdf_version_id = v.id "+"LEFT JOIN pdf_lssue l ON v.pdf_lssue_id = l.`id` "+"WHERE n.id = "+ Config.id;using (MySqlDataReader reader = MySqlHelper.ExecuteReader(Config.conStr, sql)){if (reader.HasRows){while (reader.Read()){//里面就是接收值了periodTxt.Text = reader.GetString(0);dateTimePicker1.Text = reader.GetString(1);areaTxt.Text = reader.GetString(2);layoutCmb.Text = reader.GetString(3);indexTxt.Text = reader.GetString(4);subStandardTxt.Text = reader.GetString(5);titleTxt.Text = reader.GetString(6);authorTxt.Text = reader.GetString(7);contentRich.Text = reader.GetString(8);}}}

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