Record Field Exchange Functions

مقالة
08/03/2021

This topic lists the Record Field Exchange (RFX, Bulk RFX, and DFX) functions used to automate the transfer of data between a recordset object and its data source and to perform other operations on the data.

If you are using the ODBC-based classes and you have implemented bulk row fetching, you must manually override the DoBulkFieldExchange member function of CRecordset by calling the Bulk RFX functions for each data member corresponding to a data source column.

If you have not implemented bulk row fetching in the ODBC-based classes, or if you are using the DAO-based classes (obsolete), then ClassWizard will override the DoFieldExchange member function of CRecordset or CDaoRecordset by calling the RFX functions (for ODBC classes) or the DFX functions (for DAO classes) for each field data member in your recordset.

The record field exchange functions transfer data each time the framework calls DoFieldExchange or DoBulkFieldExchange. Each function transfers a specific data type.

For more information about how these functions are used, see the articles Record Field Exchange: How RFX Works (ODBC). For more information about bulk row fetching, see the article Recordset: Fetching Records in Bulk (ODBC).

For columns of data that you bind dynamically, you can also call the RFX or DFX functions yourself, as explained in the articles Recordset: Dynamically Binding Data Columns (ODBC). Additionally, you can write your own custom RFX or DFX routines, as explained in Technical Note 43 (for ODBC) and Technical Note 53 (for DAO).

For an example of RFX and Bulk RFX functions as they appear in the DoFieldExchange and DoBulkFieldExchange functions, see RFX_Text and [RFX_Text_Bulk]#rfx_text_bulk). DFX functions are very similar to the RFX functions.

RFX Functions (ODBC)

Name	Description
RFX_Binary	Transfers arrays of bytes of type CByteArray.
RFX_Bool	Transfers Boolean data.
RFX_Byte	Transfers a single byte of data.
RFX_Date	Transfers time and date data using CTime or TIMESTAMP_STRUCT.
RFX_Double	Transfers double-precision float data.
RFX_Int	Transfers integer data.
RFX_Long	Transfers long integer data.
RFX_LongBinary	Transfers binary large object (BLOB) data with an object of the CLongBinary class.
RFX_Single	Transfers float data.
RFX_Text	Transfers string data.

Bulk RFX Functions (ODBC)

Name	Description
RFX_Binary_Bulk	Transfers arrays of byte data.
RFX_Bool_Bulk	Transfers arrays of Boolean data.
RFX_Byte_Bulk	Transfers arrays of single bytes.
RFX_Date_Bulk	Transfers arrays of data of type TIMESTAMP_STRUCT.
RFX_Double_Bulk	Transfers arrays of double-precision, floating-point data.
RFX_Int_Bulk	Transfers arrays of integer data.
RFX_Long_Bulk	Transfers arrays of long integer data.
RFX_Single_Bulk	Transfers arrays of floating-point data.
RFX_Text_Bulk	Transfers arrays of data of type LPSTR.

DFX Functions (DAO)

Name	Description
DFX_Binary	Transfers arrays of bytes of type CByteArray.
DFX_Bool	Transfers Boolean data.
DFX_Byte	Transfers a single byte of data.
DFX_Currency	Transfers currency data, of type COleCurrency.
DFX_DateTime	Transfers time and date data, of type COleDateTime.
DFX_Double	Transfers double-precision float data.
DFX_Long	Transfers long integer data.
DFX_LongBinary	Transfers binary large object (BLOB) data with an object of the `CLongBinary` class. For DAO, it is recommended that you use DFX_Binary instead.
DFX_Short	Transfers short integer data.
DFX_Single	Transfers float data.
DFX_Text	Transfers string data.

=============================================

RFX_Binary

Transfers arrays of bytes between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_BINARY, SQL_VARBINARY, or SQL_LONGVARBINARY.

Syntax

void RFX_Binary(
   CFieldExchange* pFX,
   const char* szName,
   CByteArray& value,
   int nMaxLength = 255);

Parameters

pFX
A pointer to an object of class CFieldExchange. This object contains information to define the context for each call of the function. For more information about the operations a CFieldExchange object can specify, see the article Record Field Exchange: How RFX Works.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type CByteArray, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

nMaxLength
The maximum allowed length of the string or array being transferred. The default value of nMaxLength is 255. Legal values are 1 to INT_MAX. The framework allocates this amount of space for the data. For best performance, pass a value large enough to accommodate the largest data item you expect.

Remarks

Data in the data source of these types is mapped to and from type CByteArray in the recordset.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Bool

Transfers Boolean data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_BIT.

Syntax

void RFX_Bool(
   CFieldExchange* pFX,
   const char* szName,
   BOOL& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type BOOL, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Byte

Transfers single bytes between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_TINYINT.

Syntax

void RFX_Byte(
   CFieldExchange* pFX,
   const char* szName,
   BYTE& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type BYTE, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Date

Transfers CTime or TIMESTAMP_STRUCT data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_DATE, SQL_TIME, or SQL_TIMESTAMP.

Syntax

void RFX_Date(
   CFieldExchange* pFX,
   const char* szName,
   CTime& value);

void RFX_Date(
   CFieldExchange* pFX,
   const char* szName,
   TIMESTAMP_STRUCT& value);

void RFX_Date(
   CFieldExchange* pFX,
   const char* szName,
   COleDateTime& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member; the value to be transferred. The various versions of the function take different data types for value:

The first version of the function takes a reference to a CTime object. For a transfer from recordset to data source, this value is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

The second version of the function takes a reference to a TIMESTAMP_STRUCT structure. You must set up this structure yourself before the call. Neither dialog data exchange (DDX) support nor code wizard support is available for this version. The third version of the function works similarly to the first version except that it takes a reference to a COleDateTime object.

Remarks

The CTime version of the function imposes the overhead of some intermediate processing and has a somewhat limited range. If you find either of these factors too limiting, use the second version of the function. But note its lack of code wizard and DDX support and the requirement that you set up the structure yourself.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Double

Transfers double float data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_DOUBLE.

Syntax

void RFX_Double(
   CFieldExchange* pFX,
   const char* szName,
   double& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type double, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Int

Transfers integer data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_SMALLINT.

Syntax

void RFX_Int(
   CFieldExchange* pFX,
   const char* szName,
   int& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type int, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Long

Transfers long integer data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_INTEGER.

Syntax

void RFX_Long(
   CFieldExchange* pFX,
   const char* szName,
   LONG&
value );

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type long, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_LongBinary

Transfers binary large object (BLOB) data using class CLongBinary between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_LONGVARBINARY or SQL_LONGVARCHAR.

Syntax

void RFX_LongBinary(
   CFieldExchange* pFX,
   const char* szName,
   CLongBinary& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type CLongBinary, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Single

Transfers floating-point data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_REAL.

Syntax

void RFX_Single(
   CFieldExchange* pFX,
   const char* szName,
   float& value);

Parameters

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type float, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Text

Transfers CString data between the field data members of a CRecordset object and columns of a record on the data source of ODBC type SQL_LONGVARCHAR, SQL_CHAR, SQL_VARCHAR, SQL_DECIMAL, or SQL_NUMERIC.

Syntax

void RFX_Text(
   CFieldExchange* pFX,
   const char* szName,
   CString& value,
   int nMaxLength = 255,
   int nColumnType = SQL_VARCHAR,
   short nScale = 0);

Parameters

pFX
A pointer to an object of class CFieldExchange. This object contains information to define the context for each call of the function. For more information about the operations a CFieldExchange object can specify, see the article Record Field Exchange: How RFX Works.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type CString, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

nMaxLength
The maximum allowed length of the string or array being transferred. The default value of nMaxLength is 255. Legal values are 1 to INT_MAX). The framework allocates this amount of space for the data. For best performance, pass a value large enough to accommodate the largest data item you expect.

nColumnType
Used mainly for parameters. An integer indicating the data type of the parameter. The type is an ODBC data type of the form SQL_XXX.

nScale
Specifies the scale for values of ODBC type SQL_DECIMAL or SQL_NUMERIC. nScale is only useful when setting parameter values. For more information, see the topic "Precision, Scale, Length, and Display Size" in Appendix D of the ODBC SDK Programmer's Reference.

Remarks

Data in the data source of all of these types is mapped to and from CString in the recordset.

Example

This example shows several calls to RFX_Text. Notice also the two calls to CFieldExchange::SetFieldType. For parameters you must write the call to SetFieldType and its RFX call. The output column call and its associated RFX calls are normally written by a code wizard.

void CCustomer::DoFieldExchange(CFieldExchange* pFX)
{
   pFX->SetFieldType(CFieldExchange::outputColumn);
   // Macros such as RFX_Text() and RFX_Int() are dependent on the
   // type of the member variable, not the type of the field in the database.
   // ODBC will try to automatically convert the column value to the requested type
   RFX_Long(pFX, _T("[CustomerID]"), m_CustomerID);
   RFX_Text(pFX, _T("[ContactFirstName]"), m_ContactFirstName);
   RFX_Text(pFX, _T("[PostalCode]"), m_PostalCode);
   RFX_Text(pFX, _T("[L_Name]"), m_L_Name);
   RFX_Long(pFX, _T("[BillingID]"), m_BillingID);

   pFX->SetFieldType(CFieldExchange::inputParam);
   RFX_Text(pFX, _T("Param"), m_strParam);
}

Requirements

Header: afxdb.h

RFX_Binary_Bulk

Transfers multiple rows of byte data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Binary_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   BYTE** prgByteVals,
   long** prgLengths,
   int nMaxLength);

Parameters

pFX
A pointer to a CFieldExchange object. This object contains information to define the context for each call of the function. For more information, see the article Record Field Exchange: How RFX Works.

szName
The name of a data column.

prgByteVals
A pointer to an array of BYTE values. This array will store the data to be transferred from the data source to the recordset.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgByteVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

nMaxLength
The maximum allowed length of the values stored in the array pointed to by prgByteVals. To ensure that data will not be truncated, pass a value large enough to accommodate the largest data item you expect.

Remarks

The data source column can have an ODBC type of SQL_BINARY, SQL_VARBINARY, or SQL_LONGVARBINARY. The recordset must define a field data member of type pointer to BYTE.

If you initialize prgByteVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. In order to make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Bool_Bulk

Transfers multiple rows of Boolean data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Bool_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   BOOL** prgBoolVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgBoolVals
A pointer to an array of BOOL values. This array will store the data to be transferred from the data source to the recordset.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgBoolVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

Remarks

The data source column must have an ODBC type of SQL_BIT. The recordset must define a field data member of type pointer to BOOL.

If you initialize prgBoolVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Byte_Bulk

Transfers multiple rows of single bytes from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Byte_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   BYTE** prgByteVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgByteVals
A pointer to an array of BYTE values. This array will store the data to be transferred from the data source to the recordset.

Remarks

The data source column must have an ODBC type of SQL_TINYINT. The recordset must define a field data member of type pointer to BYTE.

If you initialize prgByteVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Date_Bulk

Transfers multiple rows of TIMESTAMP_STRUCT data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Date_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   TIMESTAMP_STRUCT** prgTSVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgTSVals
A pointer to an array of TIMESTAMP_STRUCT values. This array will store the data to be transferred from the data source to the recordset. For more information about the TIMESTAMP_STRUCT data type, see the topic "C Data Types" in Appendix D of the ODBC SDK Programmer's Reference.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgTSVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

Remarks

The data source column can have an ODBC type of SQL_DATE, SQL_TIME, or SQL_TIMESTAMP. The recordset must define a field data member of type pointer to TIMESTAMP_STRUCT.

If you initialize prgTSVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Double_Bulk

Transfers multiple rows of double-precision, floating-point data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Double_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   double** prgDblVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgDblVals
A pointer to an array of double values. This array will store the data to be transferred from the data source to the recordset.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgDblVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

Remarks

The data source column must have an ODBC type of SQL_DOUBLE. The recordset must define a field data member of type pointer to double.

If you initialize prgDblVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Int_Bulk

Transfers integer data between the field data members of a CRecordset object and the columns of a record on the data source of ODBC type SQL_SMALLINT.

Syntax

void RFX_Int(
   CFieldExchange* pFX,
   const char* szName,
   int& value);

Parameters

szName
The name of a data column.

Example

See RFX_Text.

Requirements

Header: afxdb.h

RFX_Long_Bulk

Transfers multiple rows of long integer data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Long_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   long** prgLongVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgLongVals
A pointer to an array of long integers. This array will store the data to be transferred from the data source to the recordset.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgLongVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

Remarks

The data source column must have an ODBC type of SQL_INTEGER. The recordset must define a field data member of type pointer to long.

If you initialize prgLongVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Single_Bulk

Transfers multiple rows of floating-point data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Single_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   float** prgFltVals,
   long** prgLengths);

Parameters

szName
The name of a data column.

prgFltVals
A pointer to an array of float values. This array will store the data to be transferred from the data source to the recordset.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgFltVals. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

Remarks

The data source column must have an ODBC type of SQL_REAL. The recordset must define a field data member of type pointer to float.

If you initialize prgFltVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

See RFX_Text_Bulk.

Requirements

Header: afxdb.h

RFX_Text_Bulk

Transfers multiple rows of character data from a column of an ODBC data source to a corresponding array in a CRecordset-derived object.

Syntax

void RFX_Text_Bulk(
   CFieldExchange* pFX,
   LPCTSTR szName,
   LPSTR* prgStrVals,
   long** prgLengths,
   int nMaxLength);

Parameters

szName
The name of a data column.

prgStrVals
A pointer to an array of LPSTR values. This array will store the data to be transferred from the data source to the recordset. Note that with the current version of ODBC, these values cannot be Unicode.

prgLengths
A pointer to an array of long integers. This array will store the length in bytes of each value in the array pointed to by prgStrVals. This length excludes the null termination character. Note that the value SQL_NULL_DATA will be stored if the corresponding data item contains a Null value. For more details, see the ODBC API function SQLBindCol in the ODBC SDK Programmer's Reference.

nMaxLength
The maximum allowed length of the values stored in the array pointed to by prgStrVals, including the null termination character. To ensure that data will not be truncated, pass a value large enough to accommodate the largest data item you expect.

Remarks

The data source column can have an ODBC type of SQL_LONGVARCHAR, SQL_CHAR, SQL_VARCHAR, SQL_DECIMAL, or SQL_NUMERIC. The recordset must define a field data member of type LPSTR.

If you initialize prgStrVals and prgLengths to NULL, then the arrays they point to will be allocated automatically, with sizes equal to the rowset size.

Note

Bulk record field exchange only transfers data from the data source to the recordset object. To make your recordset updateable, you must use the ODBC API function SQLSetPos.

For more information, see the articles Recordset: Fetching Records in Bulk (ODBC) and Record Field Exchange (RFX).

Example

You must manually write calls in your DoBulkFieldExchange override. This example shows a call to RFX_Text_Bulk, as well as a call to RFX_Long_Bulk, for data transfer. These calls are preceded by a call to CFieldExchange::SetFieldType. Note that for parameters, you must call the RFX functions instead of the Bulk RFX functions.

void CMultiCustomer::DoBulkFieldExchange(CFieldExchange* pFX)
{
   pFX->SetFieldType(CFieldExchange::outputColumn);
   RFX_Long_Bulk(pFX, _T("[CustomerID]"), &m_pCustomerID, &m_pcCustomerID);
   RFX_Text_Bulk(pFX, _T("[ContactFirstName]"), &m_pContactFirstName, &m_pcContactFirstName, 50);
   RFX_Text_Bulk(pFX, _T("[PostalCode]"), &m_pPostalCode, &m_pcPostalCode, 50);
   RFX_Text_Bulk(pFX, _T("[L_Name]"), &m_pL_Name, &m_pcL_Name, 50);
   RFX_Long_Bulk(pFX, _T("[BillingID]"), &m_pBillingID, &m_pcBillingID);

   pFX->SetFieldType(CFieldExchange::inputParam);
   RFX_Text(pFX, _T("Param"), m_strParam);
}

Requirements

Header: afxdb.h

DFX_Binary

Transfers arrays of bytes between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Binary(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   CByteArray& value,
   int nPreAllocSize = AFX_DAO_BINARY_DEFAULT_SIZE,
   DWORD dwBindOptions = 0);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

nPreAllocSize
The framework preallocates this amount of memory. If your data is larger, the framework will allocated more space as needed. For better performance, set this size to a value large enough to prevent reallocations. The default size is defined in the AFXDAO.H file as AFX_DAO_BINARY_DEFAULT_SIZE.

dwBindOptions
An option that lets you take advantage of MFC's double buffering mechanism for detecting recordset fields that have changed. The default, AFX_DAO_DISABLE_FIELD_CACHE, does not use double buffering, and you must call SetFieldDirty and SetFieldNull yourself. The other possible value, AFX_DAO_ENABLE_FIELD_CACHE, uses double buffering, and you do not have to do extra work to mark fields dirty or Null. For performance and memory reasons, avoid this value unless your binary data is relatively small.

Note

You can control whether data is double buffered for all fields by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_BYTES in DAO and type CByteArray in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Bool

Transfers Boolean data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Bool(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   BOOL& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

dwBindOptions
An option that lets you take advantage of MFC's double buffering mechanism for detecting recordset fields that have changed. The default, AFX_DAO_ENABLE_FIELD_CACHE, uses double buffering. The other possible value is AFX_DAO_DISABLE_FIELD_CACHE. If you specify this value, MFC does no checking on this field. You must call SetFieldDirty and SetFieldNull yourself.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_BOOL in DAO and type BOOL in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Byte

Transfers single bytes between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Byte(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   BYTE& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_BYTES in DAO and type BYTE in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Currency

Transfers currency data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Currency(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   COleCurrency& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, this value is taken from the specified data member, of type COleCurrency. For a transfer from data source to recordset, the value is stored in the specified data member.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_CURRENCY in DAO and type COleCurrency in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_DateTime

Transfers time and date data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_DateTime(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   COleDateTime& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. The function takes a reference to a COleDateTime object. For a transfer from recordset to data source, this value is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_DATE in DAO and type COleDateTime in the recordset.

Note

COleDateTime replaces CTime and TIMESTAMP_STRUCT for this purpose in the DAO classes. CTime and TIMESTAMP_STRUCT are still used for the ODBC-based data access classes.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Double

Transfers double float data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Double(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   double& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_R8 in DAO and type double float in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Long

Transfers long integer data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Long(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   long& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_I4 in DAO and type long in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_LongBinary

Important It is recommended that you use DFX_Binary instead of this function.

Syntax

void AFXAPI DFX_LongBinary(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   CLongBinary& value,
   DWORD dwPreAllocSize = AFX_DAO_LONGBINARY_DEFAULT_SIZE,
   DWORD dwBindOptions = 0);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type CLongBinary, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

dwPreAllocSize
The framework preallocates this amount of memory. If your data is larger, the framework will allocated more space as needed. For better performance, set this size to a value large enough to prevent reallocations.

dwBindOptions
An option that lets you take advantage of MFC's double buffering mechanism for detecting recordset fields that have changed. The default, AFX_DISABLE_FIELD_CACHE, does not use double buffering. The other possible value is AFX_DAO_ENABLE_FIELD_CACHE. Uses double buffering, and you do not have to do extra work to mark fields dirty or Null. For performance and memory reasons, avoid this value unless your binary data is relatively small.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

DFX_LongBinary is provided for compatibility with the MFC ODBC classes. The DFX_LongBinary function transfers binary large-object (BLOB) data using class CLongBinary between the field data members of a CDaoRecordset object and the columns of a record on the data source. Data is mapped between type DAO_BYTES in DAO and type CLongBinary in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Short

Transfers short integer data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Short(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   short& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type short, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_I2 in DAO and type short in the recordset.

Note

DFX_Short is equivalent to RFX_Int for the ODBC-based classes.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Single

Transfers floating-point data between the field data members of a CDaoRecordset object and the columns of a record on the data source.

Syntax

void AFXAPI DFX_Single(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   float& value,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_R4 in DAO and type float in the recordset.

Example

See DFX_Text.

Requirements

Header: afxdao.h

DFX_Text

Transfers CString data between the field data members of a CDaoRecordset object and columns of a record on the data source.

Syntax

void AFXAPI DFX_Text(
   CDaoFieldExchange* pFX,
   LPCTSTR szName,
   CString& value,
   int nPreAllocSize = AFX_DAO_TEXT_DEFAULT_SIZE,
   DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE);

Parameters

pFX
A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function.

szName
The name of a data column.

value
The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type CString, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.

Note

You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.

Remarks

Data is mapped between type DAO_CHAR in DAO (or, if the symbol _UNICODE is defined, DAO_WCHAR) and type CString in the recordset. n

Example

This example shows several calls to DFX_Text. Notice also the two calls to CDaoFieldExchange::SetFieldType. You must write the first call to SetFieldType and its DFX call. The second call and its associated DFX calls are normally written by the code wizard that generated the class.

void CCustSet::DoFieldExchange(CDaoFieldExchange* pFX)
{
   pFX->SetFieldType(CDaoFieldExchange::param);
   DFX_Text(pFX, _T("Param"), m_strParam);
   pFX->SetFieldType(CDaoFieldExchange::outputColumn);
   DFX_Short(pFX, _T("EmployeeID"), m_EmployeeID);
   DFX_Text(pFX, _T("LastName"), m_LastName);
   DFX_Short(pFX, _T("Age"), m_Age);
   DFX_DateTime(pFX, _T("hire_date"), m_hire_date);
   DFX_DateTime(pFX, _T("termination_date"), m_termination_date);

   CDaoRecordset::DoFieldExchange(pFX);
}

Requirements

Header: afxdao.h

مشاركة عبر

Record Field Exchange Functions

RFX Functions (ODBC)

Bulk RFX Functions (ODBC)

DFX Functions (DAO)

RFX_Binary

Syntax

Parameters

Remarks

Example

Requirements

RFX_Bool

Syntax

Parameters

Example

Requirements

RFX_Byte

Syntax

Parameters

Example

Requirements

RFX_Date

Syntax

Parameters

Remarks

Example

Requirements

RFX_Double

Syntax

Parameters

Example

Requirements

RFX_Int

Syntax

Parameters

Example

Requirements

RFX_Long

Syntax

Parameters

Example

Requirements

RFX_LongBinary

Syntax

Parameters

Example

Requirements

RFX_Single

Syntax

Parameters

Example

Requirements

RFX_Text

Syntax

Parameters

Remarks

Example

Requirements

RFX_Binary_Bulk

Syntax

Parameters

Remarks

Example

Requirements

RFX_Bool_Bulk

Syntax

Parameters

Remarks

Example

Requirements

RFX_Byte_Bulk

Syntax

Parameters

Remarks

Example

Requirements

RFX_Date_Bulk

Syntax

Parameters

Remarks