Xref: utzoo comp.databases:2865 comp.sys.ibm.pc:30918 comp.dcom.lans:3094
Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ukma!rutgers!bpa!dsinc!wells!mdi386!bruce
From: bruce@mdi386.UUCP (Bruce A. McIntyre)
Newsgroups: comp.databases,comp.sys.ibm.pc,comp.dcom.lans
Subject: Re: Concurrency Control + Question
Summary: USE filename INDEX filename EXCLUSIVE && for exclusive use
Message-ID: <96@mdi386.UUCP>
Date: 1 Jul 89 02:47:17 GMT
References: <25232@shemp.CS.UCLA.EDU> <221@ic2020.UUCP>
Organization: Wells Computer Systems Corp., Levittown, Pa. 19058
Lines: 47

In article <221@ic2020.UUCP>, jim@ic2020.UUCP (Jim Carter) writes:
> in article <25232@shemp.CS.UCLA.EDU>, gblee@maui.cs.ucla.edu says:
> > Please consider the following problems: ...
> The simple foxbase+ code to lock and edit a record is 
> 	find name       && lookup the correct record.
> 	if rlock()      && returns true if record lock successfull.
> 		edit          && edit this record. ( or modify somehow )
> 		unlock()      && unlock all locks you have set
> 	else
> 		... display message, that you can not lock this record.
> 	endif
> MY QUESTION: 
> The only problem I have had is on some operations that could effect ALL 
> records, Exclusive access is required.  I have not found a simple way
> to gain exclusive access.  Anyone have a simple solution ?
> > --Geunbae Lee,m UCLA-CS-AI.

The simple way is to do the following...
	USE filename INDEX index1,index2 EXCLUSIVE
	** if using CLIPPER
	IF NETERR()
		RETURN
	ENDIF
	DELETE ALL FOR condition
	PACK
	CLOSE DATABASE
This will give you exclusive use.   I will mail you my standard openfile
that does all of the good stuff, ok?  You can use it as follows:

STORE .F. TO error,lockfile
DO openfile WITH "1","filename","index1,index2",key,filter,lockfile,error
IF .NOT. error
	DO processing
ENDIF
DO closfile WITH "DBF",error

This will do all of the checking needed, under foxbase+.  I use this every
place I do file access under DOS or XENIX or LAN's.
bruce
--
=========================================================================
	Bruce A. McIntyre, McIntyre Designs, Inc. VOICE(215)322-1895
	143 Bridgetown Pike, Langhorne, Pa. 19047 DATA (215)357-2915
	{wells|lgnp1}!mdi386!bruce		bruce@wells tbit+

	Unix, Xenix, Netware and PC-DOS Applications development.
	Specializing in Database Applications since 1980.