一、Unable to connect to any of the specified MySQL hosts?
读取数据库地址错误产生的超时报警。更新输入地址,本地localhost或者127...***(*为任意值)
二、Authentication to host ‘127.0.0.1’ for user ‘root’ using method ‘caching_sha2_password’ failed with message: Unknown database ‘******’”
连接数据库名称错误
三、Authentication to host ‘127.0.0.1’ for user ‘root’ using method ‘caching_sha2_password’ failed with message: Access denied for user ‘root’@‘localhost’ (using password: YES)”
连接数据库密码错误,密码为登录密码
四、无法运行添加环境变量(与安装的过程有关,如果没有成功需要添加)
已经添加完,上一条bin 就是。
五、具体程序及界面
程序放在button.click触发
//文件明细
string server = "127.0.0.1";
string database = "inspection";
string mypwd = "Mahle1234";
string M_str_sqlcon = "server=" + server + ";username=root;password=" + mypwd + ";database=" + database;
//string M_str_sqlcon = "server = localhost; port = 3306;user = root; password =Mahle1234 ;database =inspection";
textBox1.Text = M_str_sqlcon;
//将链接MySql所有参数实例化
MySqlConnection My_con = new MySqlConnection(M_str_sqlcon); //打开数据库
//链接数据库打开
My_con.Open();
//生成字符串变量
string sqlstr = "SELECT * FROM inspection.inspectioncase;";
//实例化数据适配器(检索和保存数据)可以本地操作,然后整体传到数据库
MySqlDataAdapter SQLda = new MySqlDataAdapter(sqlstr, My_con);
//参数设置
DataSet My_Dataset = new DataSet();
//把MySql中内容填充到table中
SQLda.Fill(My_Dataset, "table");
//实例化dt
DataTable dt = new DataTable();
dt = My_Dataset.Tables["table"];
//textBox3.Text = dt.Columns[2].ToString();
textBox3.Text = "";
//把dt放到dataGridView中
dataGridView1.DataSource = dt;
My_con.Close();
总结
安装mysql后运行有时候会出现运行错误,可能是环境变量没有添加成功,需要手动添加然后正常。安装成功后删除环境变量也可以用c#调取mysql。此程序只是查看数据库内容增加.Add();删除Delete();