CRowsetImpl Class

Статья
05/05/2015

Provides a standard OLE DB rowset implementation without requiring multiple inheritance of many implementation interfaces.

template <
   class T,
   class Storage,
   class CreatorClass,
   class ArrayType = CAtlArray<Storage>, 
   class RowClass = CSimpleRow, 
   class RowsetInterface = IRowsetImpl < T, IRowset > 
>
class CRowsetImpl :  
   public CComObjectRootEx<CreatorClass::_ThreadModel>, 
   public CRowsetBaseImpl<T, Storage, ArrayType, RowsetInterface>, 
   public IRowsetInfoImpl<T, CreatorClass::_PropClass>

Parameters

T
The user's class that derives from CRowsetImpl.
Storage
The user record class.
CreatorClass
The class that contains properties for the rowset; typically the command.
ArrayType
The class that will act as storage for the rowset's data. This parameter defaults to CAtlArray, but it can be any class that supports the required functionality.

Members

Methods

NameFromDBID	Extracts a string from a DBID and copies it to the bstr passed in.
SetCommandText	Validates and stores the DBIDs in the two strings (m_strCommandText and m_strIndexText).

Overridable Methods

GetColumnInfo	Retrieves column information for a particular client request.
GetCommandFromID	Checks to see if either or both parameters contain string values, and if so, copies the string values to the data members m_strCommandText and m_strIndexText.
ValidateCommandID	Checks to see if either or both DBIDs contain string values, and if so, copies them to its data members m_strCommandText and m_strIndexText.

Data Members

m_rgRowData	By default, a CAtlArray that templatizes on the user record template argument to CRowsetImpl. Another array type class can be used by changing the ArrayType template argument to CRowsetImpl.
m_strCommandText	Contains the rowset's initial command.
m_strIndexText	Contains the rowset's initial index.

Remarks

CRowsetImpl provides overrides in the form of static upcasts. The methods control the manner in which a given rowset will validate command text. You can create your own CRowsetImpl-style class by making your implementation interfaces multiple-inherited. The only method for which you must provide implementation is Execute. Depending on what type of rowset you are creating, the creator methods will expect different signatures for Execute. For example, if you are using a CRowsetImpl-derived class to implement a schema rowset, the Execute method will have the following signature:

HRESULT Execute(LONG* pcRows, ULONG cRestrictions, const VARIANT* rgRestrictions)

If you are creating a CRowsetImpl-derived class to implement a command or session's rowset, the Execute method will have the following signature:

HRESULT Execute(LONG* pcRows, DBPARAMS* pParams)

To implement any of the CRowsetImpl-derived Execute methods, you must populate your internal data buffers (m_rgRowData).

Requirements

Header: atldb.h

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