MySQL通过实例化对象参数查询实例讲解

本篇文章给大家带来的内容是关于mysql如何通过实例化对象参数查询数据 ？（源代码），有一定的参考价值，有需要的朋友可以参考一下，希望对你有所帮助。

public static string querybyentity<t>(t t) where t : new()
{  string resultstr = string.empty;
  mysqldatareader reader = null;  try
  {
    type type = typeof(t);
    propertyinfo[] properties = type.getproperties();    string select = string.format("select * from {0} {1}", type.name, "{0}");    string where = string.empty;    foreach (propertyinfo property in properties)
    {      var value = t.getpropertyvalue<t>(property);      if (value != null && !value.equals(property.getdefaultvalue()))
      {        if (string.isnullorempty(where))
        {          where = string.format(" where {0}='{1}' ", property.name, value);
        }        else
        {          where = string.format(" {0} and {1} = '{2}' ", where, property.name, value);
        }
      }
    }    select = string.format(select, where);
 
    mysqlconnection connection = openconnection();    if (connection == null)      return resultstr;
    mysqlcommand _sqlcom = new mysqlcommand(select, connection);
    reader = _sqlcom.executereader();
    list<t> tlist = new list<t>();    while (reader.read())
    {
      t t1 = new t();      foreach (propertyinfo property in properties)
      {        if (!string.isnullorempty(reader[property.name].tostring()))
        {
          property.setmethod.invoke(t1, new object[] { reader[property.name] });
        }
      }
      tlist.add(t1);
    }
    resultstr = jsonconvert.serializeobject(tlist);
  }  catch (exception ex)
  {
    logging.error(string.format("查询数据库失败，{0}", ex.message));
  }  finally
  {    if (reader != null)
    {
      reader.close();
      reader.dispose();
    }
  }  return resultstr;
}internal static class objectextend
{  public static object getpropertyvalue<t>(this object obj, propertyinfo property)
  {
    type type = typeof(t);
    propertyinfo propertyinfo = type.getproperty(property.name);    if (propertyinfo != null)
    {      return propertyinfo.getmethod.invoke(obj, null);
    }    return null;
  }  public static object getdefaultvalue(this propertyinfo property)
  {    return property.propertytype.isvaluetype ? activator.createinstance(property.propertytype) : null;
  }
}

通过实例化参数，对属性赋值，将对象作为参数传入，反射获取对象名称，列名，列值。要求对象名与表名一致，属性与列名一致，感谢大家对的支持。