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Inside Macintosh: Interapplication Communication /
Chapter 12 - Data Access Manager / Data Access Manager Reference
Data Access Manager Routines / Low-Level Interface: Retrieving Results


DBUnGetItem

The DBUnGetItem function reverses the effect of the last call to the DBGetItem function, in the sense that the next time you call the DBGetItem function it retrieves the same item a second time.

FUNCTION DBUnGetItem (sessID: LongInt; 
                      asyncPB: DBAsyncParmBlkPtr): OSErr;
sessID
The session ID that was returned by the DBInit function.
asyncPB
A pointer to an asynchronous parameter block. If you do not want to call the function asynchronously, set this parameter to NIL.
DESCRIPTION
The DBUnGetItem function does not remove the just-retrieved data item from the input buffer. This function can reverse the effect of only one call to the DBGetItem function; you cannot use it to step back through several previously retrieved data items.

SPECIAL CONSIDERATIONS
The DBUnGetItem function may move or purge memory. You should not call this routine from within an interrupt, such as in a completion routine or a VBL task.

ASSEMBLY-LANGUAGE INFORMATION
The trap macro and routine selector for the DBUnGetItem function are
Trap macroSelector
_DBUnGetItem$040D

RESULT CODES
noErr0No error
rcDBError-802Error executing function
rcDBBadSessID-806Session ID is invalid
rcDBAsyncNotSupp-809The database extension does not support asynchronous calls
rcDBPackNotInited-813The InitDBPack function has not yet been called
SEE ALSO
For a description of the asynchronous parameter block, see page 12-56. See page 12-84 for a description of the DBGetItem function.


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© Apple Computer, Inc.
7 JUL 1996