用c#编写软件时有关于数据库的一些问题

OleDbCommand oledcmd = null;
OleDbConnection oledCon = null;
OleDbDataReader oleRed = null;
getConnection getCon = new getConnection();
oledCon = getCon.OledCon();
oledCon.Open();
string strAdd = "select * from tb_authorinfo ";
oledcmd = new OleDbCommand(strAdd, oledCon);
oleRed=oledcmd.ExecuteReader();
oleRed[0],oleRed[1],oleRed[2]都是什么意思啊？