C ＃ interaction with MySQL database - MySQL configuration and addition, deletion, query and modification operations

c# And Mysql Interaction

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1. To configure dll file

2. download Mysql And graphical auxiliary interface

This blog uses phpmyadmin Graphical management tools , Use the established phpstudy Management tools are carried out according to .

2.1phpstudy download

Small leather panel (phpstudy)

2.2 download apache and mysql

2.3 download mysql Management tools

2.4 Enable service

2.5 phpmyadmin Basic operation

2. Introduce namespace

using MySql.Data.MySqlClient;

3. Create corresponding static fields

Class name	Description
MySqlConnection	Database connection class
MySqlCommand	The class that executes statements on the database
MySqlDataReader	Provide a way from MySQL Database one-way reading method

private static MySqlConnection conn;
private static MySqlCommand cmd;
private static MySqlDataReader reader;

4.MySqlConnection- Connect and close the database

4.1 Connect to database

MySqlConnection(server,database,user,password)

Parameter	Description
server	Server address -ip, Local use localhost Can
database	Corresponding database
user	Enter the database account name
password	Enter the database password
charset	Optional , Specify character encoding , Chinese garbled code may need to be modified

conn = new MySqlConnection(connstr);

This statement only instantiates a MySqlConnection object , It also needs to go through conn.open() Connect to the database .

 static void ContoSQL()
        {           
            string connstr = "server=localhost;database=user;user=root;password=root;charset = uft8";
            conn = new MySqlConnection(connstr);
            conn.Open();    // Establishing a connection , Open database 
            Console.WriteLine(" Open database successfully ");
        }

4.2 Close the connection , Release resources

Close the connection to the database , But don't clean up the cache

conn.close();
conn.Dispose()

4.3 Other common attributes

The specific details MySqlConnection Methods

attribute	describe
ServerVersionser	mysql Server version
State	Connection status

 static void ContoSQL()
        {           
            string connectStr = "server=localhost;database=user;user=root;password=root;";
            conn = new MySqlConnection(connectStr);
            conn.Open();    // Establishing a connection , Open database 
            Console.WriteLine("ServerVersion: " + conn.ServerVersionser +
"\nState: " + conn.State.ToString());
            conn.Close();

        }

5 Data addition, deletion, query and modification

cmd = new MySqlCommand(sql, conn);// utilize sql Statement and a connection object instantiation MysqlDataCommand object 
cmd.ExecuteNonQuery();// perform SQL sentence , And return the number of rows affected . Generally used in addition, deletion and modification 
reader=cmd.ExecuteReader();// Execute the query statement and pass the information to MysqlDataReader class 

5.1 Insert data into

string sql="insert into test( Field name 1, Field name 2) values('22','ChenChen')";   
string sql = "insert into test(username,F1) values('22','ChenChen')";   

 static void InsertSQL(string sql)
        {
            try
            {
                ContoSQL();             
                cmd = new MySqlCommand(sql, conn);
				cmd.ExecuteNonQuery(); // perform sql sentence 
            }
            catch (Exception ex)// If there is an error in execution, execute the internal statement , Close connection after execution 
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }

5.2 Data update

string sql = "update  Data table name  set  Field name  = 'FaFa' where  Field name  = '2002' ";   
string sql = "update test set F1 = 'FaFa' where username = '2002' ";   

static void UpdateSQL(string sql)
        {          
            try
            {
                ContoSQL();  // Establishing a connection              
                cmd = new MySqlCommand(sql, conn);
				cmd.ExecuteNonQuery();   // perform sql sentence 

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }

5.3 Data deletion

string sql = "Delete from test where username = '22' "; 

 static void DeleteSQL(string sql)
        {      
            try
            {
                ContoSQL();             
                cmd = new MySqlCommand(sql, conn);
				cmd.ExecuteNonQuery();   
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();  
            }

5.4 Data query

1. Usage of several common query statements

string sql ="select * from  Data table name  "
string sql = "select * from test";// Read all lines 
string sql = "select* from test where username = '2002'"; // Read the specified line 
string sql = "select* from test where  password ='2'and username=2002";// Multiple constraints 
string sql = "select username, password ,F1 from test where  password ='2'and username=2002"; // Read the specified column 

2. obtain reader Method of data

Method	explain
reader[" Field name "]	Associative array , Get the data through the field name and return object type , Need to pass .Tostring() transformation
reader[num]	The index array , By reading the sorting corresponding to the field , from 0 Start
reader.GetString(" Field name /num")	Same as above

For more information, see MySqlDataReader Class

Console.WriteLine(reader["username"].ToString() +' '+ reader[" password "].ToString()+' '+ reader["F1"].ToString());
Console.WriteLine(reader[0].ToString() +' '+ reader[1].ToString()+' '+ reader[2].ToString());

static void ReadSQL(string sql)
        {
            try
            {
                ContoSQL();
                cmd = new MySqlCommand(sql, conn);
                reader = cmd.ExecuteReader();
                while (reader.Read())    Read data line by line , No data is returned in the next row false
                {
                    Console.WriteLine(reader["username"].ToString() +' '+ reader["F1"].ToString()+' '+reader["F2"]);                 
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }

6. Add, delete, check and modify examples

 		using MySql.Data.MySqlClient;// Reference namespace , Add to first line 
		private static MySqlConnection conn;
        private static MySqlCommand cmd;
        private static MySqlDataReader reader;


        static void ContoSQL()
        {           
            string connectStr = "server=localhost;database=user;user=root;password=root;";
            conn = new MySqlConnection(connectStr);
            conn.Open();    // Establishing a connection , Open database 
            Console.WriteLine(" Open database successfully ");
        }
        /// <summary>
        ///  Read database data 
        /// </summary>
        /// <param name="sql"> Executive sql sentence </param>

        static void ReadSQL(string sql)
        {
            try
            {
                 ContoSQL();
                 cmd = new MySqlCommand(sql, conn);
                 reader = cmd.ExecuteReader();

                while (reader.Read())   // Traverse the data in the table 
                {
                    Console.WriteLine(reader[0].ToString() +' '+ reader[" password "].ToString()+' '+ reader["F1"].ToString());
             
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }
        static void InsertSQL(string sql)
        {
            try
            {
                ContoSQL();                     
                cmd = new MySqlCommand(sql, conn);
				cmd.ExecuteNonQuery();  

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }
        static void UpdateSQL(string sql)
        {
            
            try
            {
                ContoSQL();               
                cmd = new MySqlCommand(sql, conn);
                result = cmd.ExecuteNonQuery();

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }
        static void DeleteSQL(string sql)
        {
            
            try
            {
                ContoSQL();              
                cmd = new MySqlCommand(sql, conn);
                cmd.ExecuteNonQuery();  
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();   // Close the connection 
            }
        }
        static void Main(string[] args)
        {
            string sql = "select username, password ,F1 from test where  password ='2'and username=2002";             
            ReadSQL(sql);
            sql = "select * from test";
            ReadSQL(sql);        
        }