Groups db_column attributes that participate in IAccessor-based binding.

[ db_accessor( 
   num, 
   auto 
) ]

Parameters

num

Specifies the accessor number (a zero-based integer index). You must specify accessor numbers in increasing order, using integers or defined values.

auto (optional)

A Boolean value that specifies whether the accessor is automatically retrieved (TRUE) or not retrieved (FALSE). This parameter is optional; if you do not specify auto, the default is TRUE.

Attribute Context

For more information about the attribute contexts, see Attribute Contexts.

Remarks

db_accessor defines the underlying OLE DB accessor for subsequent db_column and db_param attributes within the same class or function. db_accessor is usable at member level and is used to group db_column attributes that participate in OLE DB IAccessor-based binding. It is used in conjunction with either the db_table or db_command attributes. Calling this attribute is similar to calling the >BEGIN_ACCESSOR and >END_ACCESSOR macros.

db_accessor generates a rowset and binds it to the corresponding accessor maps. If you do not call db_accessor, accessor 0 will automatically be generated, and all column bindings will be mapped to this accessor block.

db_accessor groups database column bindings into one or more accessors. For a discussion of the scenarios in which you need to use multiple accessors, see >Using Multiple Accessors on a Rowset. Also see "User Record Support for Multiple Accessors" in >User Records.

Example

The following example uses db_accessor to group columns in the Orders table from the Northwind database into two accessors. Accessor 0 is an automatic accessor, and accessor 1 is not.

// cpp_attr_ref_db_accessor.cpp
// compile with: /LD /link /OPT:NOREF
#define _ATL_ATTRIBUTES
#include <atlbase.h>
#include <atldbcli.h>

[
   db_command(L"SELECT LastName, FirstName FROM Orders") 
]
class CEmployees
{
public:
   [ db_accessor(0, TRUE) ];
   [ db_column(1) ] LONG m_OrderID;
   [ db_column(2) ] TCHAR m_CustomerID[6];
   [ db_column(4) ] DBTIMESTAMP m_OrderDate;

   [ db_accessor(1, FALSE) ];
   [ db_column(8) ] CURRENCY m_Freight;
};

See Also

OLE DB Consumer Attributes | Attributes Samples