使用C#对数据库进行增删改查操作（三）

运行环境：visual studio 2017 .NET窗口控制台程序。

安装好数据库环境后找到C:\Program Files (x86)\MySQL\Connector NET 6.10\Assemblies\v4.5.2路径下的MySql.Data动态库文件，并导入C#工程。如果没有改文件夹，在安装MySQL时需勾选Connector C#安装程序。

具体查询与插入的代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace LinkMySQL
{
    class Program
    {
        static void Main(string[] args)
        {
            //datasource:IP地址;port:端口号;database:数据库名;user:用户名;password:密码;
            public const string ConnectionString = "datasource=127.0.0.1;port=3306;database=gamedata;user=root;password=root;";
            MySqlConnection connection = new MySqlConnection(ConnectionString);
            try
            {
                connection.Open();
            }
            catch (Exception ex)
            {
                Console.WriteLine("连接数据库异常：" + ex);
                return;
            }

            VerifyUser(connection,"sy","sy");
            
            //依次类推删除操作
            //MySqlCommand cmdInsert = new MySqlCommand("delete from user where id = @id", connection);
            //cmdInsert.Parameters.AddWithValue("id", 1);

            //依次类推更新操作
            //MySqlCommand cmdInsert = new MySqlCommand("updata user set password = @pwd where id = 1", connection);
            //cmdInsert.Parameters.AddWithValue("pwd", "sadad");

            connection.Close();
        }

        /// <summary>
        /// 插入操作(用于用户注册)
        /// </summary>
        /// <param name="_connection"></param>
        /// <param name="_username"></param>
        /// <param name="_password"></param>
        /// <returns></returns>
        public bool Register(MySqlConnection _connection, string _username, string _password)
        {
            try
            {
                MySqlCommand cmdInsert = new MySqlCommand("insert into user set username=@un,password=@pwd", _connection);
                cmdInsert.Parameters.AddWithValue("un", _username);
                cmdInsert.Parameters.AddWithValue("pwd", _password);
                cmdInsert.ExecuteNonQuery();
                return true;
            }
            catch (Exception e)
            {
                Console.WriteLine("Register函数调用出错：" + e);
                return false;
            }
        }

        /// <summary>
        /// 根据账号密码查询(用于用户登入时校验账号密码)
        /// </summary>
        /// <param name="_username"></param>
        /// <param name="_password"></param>
        public Bool VerifyUser(MySqlConnection _connection, string _username, string _password)
        {
            MySqlDataReader reader = null;
            try
            {
                MySqlCommand cmd = new MySqlCommand("select * from user where username = @username and password = @password", _connection);
                cmd.Parameters.AddWithValue("username", _username);
                cmd.Parameters.AddWithValue("password", _password);

                //执行数据库的查询语句
                reader = cmd.ExecuteReader();
                if (reader.Read())
                {
                    int id = reader.GetInt32("id");
                    return true;
                }
            }
            catch
            {
                Console.WriteLine("VerifyUser函数调用出错： 不存在该用户!");
            }
            finally
            {
                if (reader != null) reader.Close();
            }

            return false;
        }
    }
}