using System; 
using System.Collections.Generic; 
using System.ComponentModel; 
using System.Data; 
using System.Drawing; 
Using System. Linq; 
Using System. The Text; 
using System.Threading.Tasks; 
Using System. Windows. Forms; 

Using MySql. Data. MySqlClient; 

The namespace project1 
{
Public partial class Form1: Form 
{
Public _click () 
{
InitializeComponent (); 



} 

Private void button1_Click (object sender, EventArgs e) 
{
//MySql Data. MySqlClient. MySqlConnection conn1; 
String connStr="server=128.0.0.1; User=root; The database=mytest; Port=3306; Password=root; "; 
MySqlConnection conn=new MySqlConnection (connStr); 
Task. Factory. StartNew (()=& gt; 
{

Try 
{

Conn. The Open (); 

MessageBox. Show (" database connection success!" ); 

//int current=5; 
//int vol=6; 
////int temp=7; 
//MySqlCommand CMD=new MySqlCommand (" insert into user set current='" + current + "' "+", vol='" + vol + "' ", conn); 

String SQL="insert into analog (current, vol) values (' 2 ', '83')";//write 
//string SQL="update analog to set the current='0', vol='0' where id='1'";//change 
//string SQL="delete from analog to the where id='1'";//delete 
MySqlCommand CMD=new MySqlCommand (SQL, conn); 

CMD. ExecuteNonQuery (); 

//Perform database operations 
} 
The catch (MySqlException ex)//(Exception ex) 
{
MessageBox. Show (" the database connection failed!" ); 

The switch (ex. Number) 
{
Case 0: 
//the Console. WriteLine (" always connect to the server. Contact administrator "); 
MessageBox. Show (" is always the connect to server. Contact the administrator "); 
break; 
Case: 1045 
//the Console. WriteLine (" Invalid username/password, both please try again "); 
MessageBox. Show (" Invalid username/password, both please try again "); 
break; 
} 
} 
Conn. Close (); 
}); 
//try 
//{

////conn. The Open (); 

//MessageBox. Show (" database connection success!" ); 

////int current=5; 
////int vol=6; 
//////int temp=7. 
////MySqlCommand CMD=new MySqlCommand (" insert into user set current='" + current + "' "+", vol='" + vol + "' ", conn); 

//string SQL="insert into analog (current, vol) values (' 2 ', '83')";//write 
////string SQL="update analog to set the current='0', vol='0' where id='1'";//change 
////string SQL="delete from analog to the where id='1'";//delete 
//MySqlCommand CMD=new MySqlCommand (SQL, conn); 

//CMD ExecuteNonQuery (); 

////Perform database operations 
//} 
//catch (MySqlException ex)//(Exception ex) 
//{
////MessageBox. Show (" database connection failed!" ); 

//the switch (ex. Number) 
//{
//case 0: 
////the Console. WriteLine (" always connect to the server. Contact the administrator "); 
//MessageBox. Show (" always connect to the server. Contact the administrator "); 
//break; 
//case, 1045: 
////the Console. WriteLine (" Invalid username/password, both please try again "); 
//MessageBox. Show (" Invalid username/password, both please try again "); 
//break; 
//} 
//} 
//conn. Close (); 
} 

Private async void button2_Click (object sender, EventArgs e) 
{
String connStr="server=128.0.0.1; User=root; The database=mytest; Port=3306; Password=root; "; 
MySqlConnection conn=new MySqlConnection (connStr); 
Try 
{

Await conn. OpenAsync (); 

String SQL="select * from analog"; 
MySqlCommand CMD=new MySqlCommand (SQL, conn); 
MySqlDataReader reader=CMD. ExecuteReader ();//execution ExecuteReader () returns a MySqlDataReader object 
While (reader. The Read (),//the initial index is 1, Read the next row data, the return value is a bool 
{
//the Console. WriteLine (reader [0]. The ToString () + reader [1]. The ToString () + reader [2]. The ToString ()); 
//the Console. WriteLine (reader. GetInt32 (0) + reader. Get string (1) + reader. Get string (2)); 
//the Console. WriteLine (reader. GetInt32 (" userid ") + reader. Get string (" username ") + reader. Get string (" password "));//"userid" is the corresponding database column names, recommend this way 
TextBox1. AppendText (" id="+ reader. GetInt16 (" id") + "is the current=" + reader. GetInt16 (" current ") + "vol=" + reader. GetInt16 (" vol ") + "\ r \ n"); 
} 


//Perform database operations 
} 
The catch (MySqlException ex)//(Exception ex) 
{
//MessageBox. Show (" database connection failed!" ); 

The switch (ex. Number) 
{
Case 0: 
//the Console. WriteLine (" always connect to the server. Contact administrator "); 
//MessageBox. Show (" always connect to the server. Contact the administrator "); 
break; 
Case: 1045 
//the Console. WriteLine (" Invalid username/password, both please try again "); 
//MessageBox. Show (" Invalid username/password, both please try again "); 
break; 
} 
} 
Conn. Close (); 
} 
} 
} 

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