MySQL 数据库、表的创建、导出与C#代码的增删改查

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本文链接： https://blog.csdn.net/qq_28474981/article/details/90413958

1.数据库创建

在MySQL Workbench上创建数据库
（1）建立与MySQL服务器的连接

（2）输入密码

（3）点击图片中的图标，创建一个数据库

后面按照提示点击即可

2.创建表

在第一个红箭头处添加字段，设置类型；第二个红箭头处设置属性；第三个红箭头处应用配置

点击图标进入表编辑视图

3.表数据导出

选择数据库，选择表，配置路径，开始导出

4.使用C#代码进行增删改查

4.0 环境配置

使用NuGet导出库MySql.Data

4.1 使用的接口解释

4.1.1 MySqlConnection 建立与SQL数据库的链接

（1）生成对象

 MySqlConnection connect= new MySqlConnection(" server=127.0.0.1;port=3306;user=root;password=root;database =user;");

（2）建立连接

connect.Open();

（3）断开连接

connect.Close();

4.1.2 MySqlCommand 将SQL语句传入MySQL Server并执行

（1）生成对象

string sql = "select * from user ";
MySqlCommand cmd = new MySqlCommand(sql, connect);

（2）执行
执行方法有四种：
(1)执行增删改时使用，同步

int resultCode=cmd.ExecuteNonQuery();

(2)执行增删改时使用，异步

IAsyncResult result=cmd.BeginExecuteNonQuery();
int resultCode=cmd.EndExecuteNonQuery(result);

(3)执行查时使用，同步

MySqlDataReader dataReader=cmd.ExecuteReader();

(4)执行查时使用，异步

IAsyncResult result=cmd.BeginExecuteReader();
MySqlDataReader dataReader=cmd.EndExecuteReader(result);

4.1.3 MySqlDataReader 读取查询返回的数据

（1）读取数据

     while (dataReader.Read())
      {
      		Console.Log(dataReader.GetInt32("userid") + dataReader.GetString("username") + dataReader.GetString("password"));
      }               
      registerReader.Close();

4.2 增加（insert）

    /// <summary>
    /// 插入数据
    /// </summary>
    /// <param name="connect">与SQL的链接</param>
    /// <param name="tableName">表名</param>
    /// <param name="insertK2V">要插入的数据键值对</param>
    /// <returns>是否插入成功</returns>
    public bool Insert(MySqlConnection connect,string tableName,Dictionary<string,string> insertK2V)
    {
        string sql = "insert into ";
        sql += "user(";
        string[] keys = insertK2V.Keys.ToArray();
        for (int i = 0; i < keys.Length; i++)
        {
            sql += keys[i];
            if (i!= keys.Length - 1)
            {
                sql += ",";
            }
        }
        sql += ") values(";
        string[] values = insertK2V.Values.ToArray();
        for (int i = 0; i < values.Length; i++)
        {
            sql += "'" + values[i] + "'";
            if (i != values.Length - 1)
            {
                sql += ",";
            }
        }
        sql += ")";
        LogUtils.LogInfo(sql);
        MySqlCommand cmd = new MySqlCommand(sql, connect);
        int result=cmd.ExecuteNonQuery();
        return result==1;
    }

4.3 删除（delete）

    /// <summary>
    /// 删除
    /// </summary>
    /// <param name="connect">与SQL的链接</param>
    /// <param name="tableName">表名</param>
    /// <param name="selectK2V">选择条件键值对</param>
    /// <returns>是否删除成功</returns>
    public bool Delete(MySqlConnection connect, string tableName, Dictionary<string, string> selectK2V)
    {
        string sql = "delete from user where ";
        foreach (var item in selectK2V)
        {

            sql += " "+item.Key + "='" + item.Value + "' and";
        }
        sql = sql.Remove(sql.Length - 3,3);
        MySqlCommand cmd = new MySqlCommand(sql, connect);
        int result = cmd.ExecuteNonQuery();
        return result == 1;
    }

4.4 修改（Update）

    /// <summary>
    /// 修改
    /// </summary>
    /// <param name="connect">与SQL的链接</param>
    /// <param name="tableName">表名</param>
    /// <param name="updateK2V">要更新的数据的键值对</param>
    /// <param name="selectK2V">选择的条件</param>
    /// <returns></returns>
    public bool Update(MySqlConnection connect, string tableName, Dictionary<string, string> updateK2V, Dictionary<string, string> selectK2V)
    {
        string sql = "update user set ";
        foreach (var item in updateK2V)
        {
            sql += "'" + item.Key.ToString() + "=" + "'" + item.Value + "'" + ",";
        }
        sql = sql.Remove( sql.Length - 1) ;
        sql += " where ";
        foreach (var item in selectK2V)
        {
            sql+= sql += "'" + item.Key.ToString() + "=" + "'" + item.Value + "'" + ",";
        }
        sql=sql.Remove(sql.Length - 1);

        MySqlCommand cmd = new MySqlCommand(sql, connect);
        int result = cmd.ExecuteNonQuery();
        return result == 1;
    }

4.5 查找（Select）

    /// <summary>
    /// 查找
    /// </summary>
    /// <param name="connect">与SQL的链接</param>
    /// <param name="tableName">表名</param>
    /// <param name="selectK2V">选择条件键值对</param>
    /// <returns>找到的数据集</returns>
    public MySqlDataReader Select(MySqlConnection connect, string tableName, Dictionary<string, string> selectK2V)
    {
        string sql = "select * from " + tableName;
        if (selectK2V.Count > 0)
        {
            sql += " where";
        }
        foreach (var item in selectK2V)
        {
            sql += " " + item.Key + "='" + item.Value + "' and";
        }
        sql = sql.Remove(sql.Length - 3, 3);
        LogUtils.LogInfo(sql);
        MySqlCommand cmd = new MySqlCommand(sql, connect);
        MySqlDataReader reader = cmd.ExecuteReader();

        return reader;
    }