Interfaces Used by OLE DB Error Objects

The consumer uses this interface to determine whether an object can return OLE DB error objects and, if so, which interfaces on that object can return OLE DB error objects.

The error lookup service is required by the error object code in the OLE DB SDK and is used by that code to implement IErrorRecords and IErrorInfo. For more information, see "Error Lookup Services" later in this chapter.

This is the main interface through which OLE DB error objects are accessed.

OLE DB error objects expose IErrorInfo at the top level (that is, on the object itself) only so they can be treated by the Automation DLL and by Automation consumers as Automation error objects. If the methods on this interface are called, they will retrieve the information from record 0 using the default locale ID.

To retrieve error information from other records, the consumer calls IErrorRecords::GetErrorInfo and passes a record number and locale ID. The OLE DB error object returns a pointer to an IErrorInfo interface, which will return error information from the specified error record using the specified locale ID. The IErrorInfo pointer returned on a particular record is not the same as the IErrorInfo interface pointer exposed by the OLE DB error object through QueryInterface. For more information about how these interface pointers are used, see "How a Consumer Retrieves an OLE DB Error Object" and "Error Lookup Services" later in this chapter.

OLE DB error objects are created by a class factory exposed by the error object code in the OLE DB SDK. You can create them by calling CoCreateInstance with the CLSID_EXTENDEDERRORINFO class ID or by calling IClassFactory::CreateInstance on a class factory object retrieved with DllGetClassObject. If the provider frequently creates error objects, the latter method is faster and therefore preferred.

OLE DB error objects cannot be created by the CreateErrorInfo function in the Automation DLL because the function can create only Automation error objects.

GetErrorInfo transfers ownership of the OLE DB error object on the current thread from the Automation DLL to the consumer. It identifies error objects by their IErrorInfo interface pointer, which is one reason OLE DB error objects directly expose IErrorInfo.

SetErrorInfo transfers ownership of the OLE DB error object on the current thread from the provider to the Automation DLL. It identifies error objects by their IErrorInfo interface pointer, which is one reason OLE DB error objects directly expose IErrorInfo.