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db_accessor

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

Applies to Attribute blocks
Repeatable No
Required attributes None
Invalid attributes None

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

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