Data Access Manager Routines

The Data Access Manager has high-level routines, low-level routines, and

routines that manipulate result handlers. All of the low-level routines and

some of the high-level routines have as a parameter a pointer to an

asynchronous parameter block. If you specify a nonzero value for this

parameter, the database extension executes the function asynchronously-that

is, it returns control to the Data Access Manager before the routine has

completed execution, and the Data Access Manager returns control to your

application. If you specify NIL for the pointer to the asynchronous parameter

block, the database extension does not return control to your application until

the routine has finished execution.Your application must call the

WaitNextEvent function periodically to allow an asynchronous routine to

complete execution. The WaitNextEvent function is described in the

You can tell when an asynchronous routine has completed execution and check

the result code by looking at values in the asynchronous parameter block. The

asynchronous parameter block is described in the section,

Note: A noErr result code returned by a routine that has been

called asynchronously indicates only that the routine began execution

successfully. You must check the result field of the asynchronous

parameter block for the final result of the routine.

Assembly-language note: You can invoke each of the

Data Access Manager routines with a macro that has the same

name as the routine, but preceded with an underscore; for example,

the macro for the DBInit function is named _DBInit. Each of these

macros places a routine selector in the D0 register and calls the trap

_Pack13.