A CDBVariant object represents a variant data type for the MFC ODBC classes. CDBVariant is similar to COleVariant; however, CDBVariant does not use OLE. CDBVariant allows you to store a value without worrying about the value’s data type. CDBVariant tracks the data type of the current value, which is stored in a union.Class CRecordset utilizes CDBVariant objects in three member functions: GetFieldValue, GetBook, and SetBook. For example, GetFieldValue allows you to dynamically fetch data in a column. Because the data type of the column may not be known at run time, GetFieldValue uses a CDBVariant object to store the column’s data.
解决方案 »
免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货