C# 进行 MySQL连接 增删改查操作

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u012278016/article/details/90905349

static void connMySQL()
{
	//MySQL建立连接

	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");
	}
	catch (Exception e)
	{
		Console.WriteLine(e.ToString());
	}
	finally
	{
		conn.Close();
	}
	Console.ReadKey();
}



static void selectMySQL()
{
	//select查询操作
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "select * from userinfo"; //从表userinfo查询所有行数据
		MySqlCommand cmd = new MySqlCommand(sql, conn);

		//三种不同的执行sql语句方式, 在合适的场合选择使用
		//cmd.ExecuteReader();//执行一些查询
		//cmd.ExecuteNonQuery();//插入 删除
		//cmd.ExecuteScalar();//执行一些查询 返回单个的值

		MySqlDataReader reader = cmd.ExecuteReader();// reader 中保存查询到的数据 对应表中一行行数据保存

		reader.Read();// 读取一行
		Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());

		reader.Read();// 读取第二行
		Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());

		//遍历输出所有查询到的数据
		//reader.Read()在读取下一行数据，如果读取成功，返回true, 如果没有下一行数据，读取失败，返回值为 false
		while (reader.Read()) //利用reader.Read() 返回值 这个特性在while循环中遍历所有读取到数据
		{
			Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());
		}
	}
	catch (Exception e)
	{
		Console.WriteLine(e.ToString());
	}
	finally
	{
		conn.Close();
	}
	Console.ReadKey();
}


static void insertMySQL()
{
	//Insert插入操作
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "insert into userinfo(uname, upwd) values('kkk', '234')"; //插入数据到表userinfo
		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();
}




static void updateMySQL()
{
	//update修改操作
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "update userinfo set uname='fff', upwd='789' where id = 3"; //从表userinfo查询所有行数据
		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();
}


static void deleteMySQL()
{
	//delete删除操作
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "delete from userinfo where id = 3"; //从表userinfo删除id为3的一行数据
		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();
}


//执行一些查询 返回单个的值 使用ExecuteScalar()函数
static void readUsersCount()
{
	//delete删除操作
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "select count(*) from userinfo"; //从表userinfo中获取数据 个数
		MySqlCommand cmd = new MySqlCommand(sql, conn);

		/*
		 * 得到数据个数
		MySqlDataReader reader = cmd.ExecuteReader();
		reader.Read();
		int count = Convert.ToInt32(reader[0].ToString());
		Console.WriteLine(count);
		*/

		//和上面的执行结果一样 得到数据个数
		object o = cmd.ExecuteScalar();
		int count = Convert.ToInt32(o.ToString());
		Console.WriteLine(count);


	}
	catch (Exception e)
	{
		Console.WriteLine(e.ToString());
	}
	finally
	{
		conn.Close();
	}
	Console.ReadKey();
}


static void readDateOtherMethod()
{
	//查询取得数据的其他方式
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		string sql = "select * from userinfo"; //从表userinfo中获取数据 个数
		MySqlCommand cmd = new MySqlCommand(sql, conn);


		MySqlDataReader reader = cmd.ExecuteReader();
		while (reader.Read())
		{
			//普通方式
			//Console.WriteLine(reader[0].ToString() + reader[1].ToString() + reader[2].ToString());

			//根据索引取得数据
			//Console.WriteLine(reader.GetInt32(0) + " " + reader.GetString(1) + " " + reader.GetString(2));

			//根据列名取得数据
			Console.WriteLine(reader.GetInt32("id") + " " + reader.GetString("uname") + " " + reader.GetString("upwd"));
		}
	}
	catch (Exception e)
	{
		Console.WriteLine(e.ToString());
	}
	finally
	{
		conn.Close();
	}
	Console.ReadKey();
}


//根据用户名和密码查询数据库中是否存在
static bool selectDateForRule(string username, string password)
{
	string connectStr = "server=127.0.0.1; port=3306; database=editorserver; user=root; password=123456;";
	MySqlConnection conn = new MySqlConnection(connectStr); //并没有去跟数据库建立链接
	try
	{
		conn.Open();
		Console.WriteLine("已经建立连接");

		//我们自己按照查询条件去组拼sql
		//string sql = "select * from userinfo where uname = '" + username + "' and upwd = '" +  password + "'"; 

		//其他的组拼sql方式
		string sql = "select * from userinfo where uname = @username and upwd = @password ";

		MySqlCommand cmd = new MySqlCommand(sql, conn);
		cmd.Parameters.AddWithValue("username", username);
		cmd.Parameters.AddWithValue("password", password);
		

		MySqlDataReader reader = cmd.ExecuteReader();
		while (reader.Read())
		{
			return true;
		}
	}
	catch (Exception e)
	{
		Console.WriteLine(e.ToString());
	}
	finally
	{
		conn.Close();
	}

	Console.ReadKey();
	return false;

}