CDBVariant Class

發行項
04/28/2015

Represents a variant data type for the MFC ODBC classes.

class CDBVariant

Members

Public Constructors

Name	Description
CDBVariant::CDBVariant	Constructs a CDBVariant object.

Public Methods

Name	Description
CDBVariant::Clear	Clears the CDBVariant object.

Public Data Members

Name	Description
CDBVariant::m_dwType	Contains the data type of the currently stored value. Type DWORD.

Public Union Members

Name	Description
CDBVariant::m_boolVal	Contains a value of type BOOL.
CDBVariant::m_chVal	Contains a value of type unsigned char.
CDBVariant::m_dblVal	Contains a value of type double.
CDBVariant::m_fltVal	Contains a value of type float.
CDBVariant::m_iVal	Contains a value of type short.
CDBVariant::m_lVal	Contains a value of type long.
CDBVariant::m_pbinary	Contains a pointer to an object of type CLongBinary.
CDBVariant::m_pdate	Contains a pointer to an object of type TIMESTAMP_STRUCT.
CDBVariant::m_pstring	Contains a pointer to an object of type CString.
CDBVariant::m_pstringA	Stores a pointer to an ASCII CString object.
CDBVariant::m_pstringW	Stores a pointer to a wide CString object.

Remarks

CDBVariant does not have a base class.

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, GetBookmark, and SetBookmark. 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.

Inheritance Hierarchy

CDBVariant

Requirements

Header: afxdb.h

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