数据库管理器学习记录

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public class MySqlManager{    //数据库连接对象    private MySqlConnection _conn;    //数据库名字    private string _dbName = "test";    //数据库源    private string _dataSource = "127.0.0.1";    //用户名    private string _userid = "root";    //密码    private string _pws = "123456";    //连接    public void Connect()    {        string str = string.Format("Server = {0};UserID = {1};Password ={2};Database = {3}",_dataSource,_userid,_pws,_dbName);        _conn = new MySqlConnection(str);    }    //执行非查询命令    public void ExecNonQuery(string sql)    {        MySqlCommand command = new MySqlCommand(sql, _conn);        _conn.Open();        command.ExecuteNonQuery();        command.Dispose();        _conn.Close();    }    //执行查询命令    public List<T> ExecQuery<T>(string sql)    {        List<T> objList = new List<T>();        //创建一个mysql命令        MySqlCommand command = new MySqlCommand(sql, _conn);        //打开数据库        _conn.Open();        MySqlDataReader reader = null;        //获取数据库读取器        reader = command.ExecuteReader();        //开始读        while(reader.Read())        {            T obj = Activator.CreateInstance<T>();            FieldInfo[] fields = typeof(T).GetFields();            for (int i = 0; i < reader.FieldCount; i++)            {                ReadField<T>(obj, fields[i], reader, i);            }            objList.Add(obj);        }        reader.Close();        _conn.Close();        command.Dispose();        return objList;    }    public Dictionary<int,T> ExecQueryDic<T> (string sql)    {        Dictionary<int, T> objList = new Dictionary<int, T>();        MySqlCommand command = new MySqlCommand(sql, _conn);        MySqlDataReader reader = null;        _conn.Open();        reader = command.ExecuteReader();        while(reader.Read())        {            T obj = Activator.CreateInstance<T>();            FieldInfo[] fields = typeof(T).GetFields();            for (int i = 0; i < fields.Length; i++)            {                ReadField<T>(obj, fields[i], reader,i);            }            FieldInfo fieldInfo = obj.GetType().GetField("id");            int id = (int)fieldInfo.GetValue(obj);            if(!objList.ContainsKey(id))            {                objList.Add(id, obj);            }         }        reader.Close();        _conn.Close();        command.Dispose();        return objList;    }    //从数据库中读取数据 并赋值    private void ReadField<T>(T obj,FieldInfo fieldInfo,MySqlDataReader reader,int ordinal)    {        Type type = fieldInfo.FieldType;        System.Object value = null;        if (type == typeof(int))            value = reader.GetFieldValue<int>(ordinal);        else if (type == typeof(byte))            value = reader.GetFieldValue<byte>(ordinal);        else if (type == typeof(uint))            value = reader.GetFieldValue<uint>(ordinal);        else if (type == typeof(string))            value = reader.GetFieldValue<string>(ordinal);        else if (type == typeof(float))            value = reader.GetFieldValue<float>(ordinal);        fieldInfo.SetValue(obj, value);    }}
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