Photon Server服务器端（一）

以你之姓@ 2021-09-16 13:38 348阅读 0赞

**目录**

1.控制台应用程序跟MySQL建立连接

2.利用建立好的链接执行查询命令MySQLDataReader

3.利用程序对数据进行插入Insert操作

4.利用程序对数据进行更新Update和删除Delete操作

5.利用ExecuteScalar查询得到一个值的结果

6.在查询的时候添加参数

--------------------

## 1.控制台应用程序跟MySQL建立连接 ##

添加引用MySql.Data.dll

![70][]

![70 1][]

记得引入命名空间：using MySql.Data.MySqlClient;

static void Main(string[] args)
            {
                string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    Console.WriteLine("已经建立连接");
                }
                catch(Exception e)
                {
                    Console.WriteLine(e.ToString());
                }finally
                {
                    conn.Close();
                }
                Console.ReadKey();
            }

![70 2][]

## 2.利用建立好的链接执行查询命令MySQLDataReader ##

static void Main(string[] args)
            {
                string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    string sql = "select * from users";
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    //cmd.ExecuteReader();执行一些查询
                    //cmd.ExecuteNonQuery();插入  删除
                    //cmd.ExecuteScalar();执行一些查询，返回一个单个的值
                    MySqlDataReader reader = cmd.ExecuteReader();
                    reader.Read();//读取下一页数据，如果读取成功，返回true；如果没有下一页了，读取失败的话，返回false；
                    Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());
                    reader.Read();
                    Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());
                    Console.WriteLine("---------------------------------");
                    while (reader .Read())
                    {
                        reader.Read();
                        //Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());
                        Console.WriteLine(reader .GetInt32 ("id")+reader .GetString ("username")+reader .GetString ("password"));//相比上面这种方式更加直观
                    }
                }
                catch(Exception e)
                {
                    Console.WriteLine(e.ToString());
                }finally
                {
                    conn.Close();
                }
                Console.ReadKey();
            }

![70 3][]![70 4][]

## 3.利用程序对数据进行插入Insert操作 ##

string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    string sql = "insert into users(username,password) values ('lalala','12345')";
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    int result = cmd.ExecuteNonQuery();//返回值是数据库中受影响的数据的行数
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
                finally
                {
                    conn.Close();
                }
                Console.ReadKey();

![70 5][] =》  ![70 6][]

## 4.利用程序对数据进行更新Update和删除Delete操作 ##

*  Update:

string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    string sql = "update users set username='aaaaa', password='1111' where id=2 ";
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    int result = cmd.ExecuteNonQuery();//返回值是数据库中受影响的数据的行数
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
                finally
                {
                    conn.Close();
                }
                Console.ReadKey();

![70 7][]=》![70 8][]

*  delete:

![70 9][]=》![70 10][]

## 5.利用ExecuteScalar查询得到一个值的结果 ##

string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    string sql = "select count(*) from users ";
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    //MySqlDataReader reader = cmd.ExecuteReader();
                    //reader.Read();
                    //int count= Convert .ToInt32 (reader[0].ToString());这种方式麻烦
                    object o = cmd.ExecuteScalar();//执行一些查询，返回一个单个的值（这种方式相对简单）
                    int count = Convert.ToInt32(o.ToString());
                    Console.WriteLine(count);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
                finally
                {
                    conn.Close();
                }
                Console.ReadKey();

![70 11][]![70 12][]

## 6.在查询的时候添加参数  ##

static void Main(string[] args)
            {
                Console.WriteLine(VerifyUser("aaaaa", "1111"));
                Console.WriteLine(VerifyUser("aaaaa", "1"));
                Console.ReadKey();
            }
            static bool VerifyUser(string username, string password)
            {
                string connectStr = "server=127.0.0.1;port=3306;database=my_schema;user=root;password=root";
                MySqlConnection conn = new MySqlConnection(connectStr);
                try
                {
                    conn.Open();
                    //string sql = "select * from users where username='" + username + "' and password='" + password + "'";
                    //这种方式一看就不直观，因为分号太多，容易搞混。所有还是下面这种方式比较好
                    //MySqlCommand cmd = new MySqlCommand(sql, conn);
    
                    string sql = "select * from users where username=@username and password=@password";
                    MySqlCommand cmd = new MySqlCommand(sql, conn);
                    cmd.Parameters.AddWithValue("username", username);
                    cmd.Parameters.AddWithValue("password", password);
    
                    MySqlDataReader reader = cmd.ExecuteReader();
                    if (reader.Read())
                    {
                        return true;
                    }
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
                finally
                {
                    conn.Close();
                }
                return false;
            }

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