CRecordset Class

Статья
10/16/2008

Represents a set of records selected from a data source.

class CRecordset : public CObject

Заметки

Known as "recordsets," CRecordset objects are typically used in two forms: dynasets and snapshots. A dynaset stays synchronized with data updates made by other users. A snapshot is a static view of the data. Each form represents a set of records fixed at the time the recordset is opened, but when you scroll to a record in a dynaset, it reflects changes subsequently made to the record, either by other users or by other recordsets in your application.

Примечание.
If you are working with the Data Access Objects (DAO) classes rather than the Open Database Connectivity (ODBC) classes, use class CDaoRecordset instead. For more information, see the article Overview: Database Programming.

To work with either kind of recordset, you typically derive an application-specific recordset class from CRecordset. Recordsets select records from a data source, and you can then:

Scroll through the records.
Update the records and specify a locking mode.
Filter the recordset to constrain which records it selects from those available on the data source.
Sort the recordset.
Parameterize the recordset to customize its selection with information not known until run time.

To use your class, open a database and construct a recordset object, passing the constructor a pointer to your CDatabase object. Then call the recordset's Open member function, where you can specify whether the object is a dynaset or a snapshot. Calling Open selects data from the data source. After the recordset object is opened, use its member functions and data members to scroll through the records and operate on them. The operations available depend on whether the object is a dynaset or a snapshot, whether it is updatable or read-only (this depends on the capability of the Open Database Connectivity (ODBC) data source), and whether you have implemented bulk row fetching. To refresh records that may have been changed or added since the Open call, call the object's Requery member function. Call the object's Close member function and destroy the object when you finish with it.

In a derived CRecordset class, record field exchange (RFX) or bulk record field exchange (Bulk RFX) is used to support reading and updating of record fields.

For more information about recordsets and record field exchange, see the articles Overview: Database Programming, Recordset (ODBC), Recordset: Fetching Records in Bulk (ODBC), and Record Field Exchange (RFX). For a focus on dynasets and snapshots, see the articles Dynaset and Snapshot.