The LA Fox Developer Newsletter

March 2000

ADO Jumpstart (Con’t from page 3)

Close method —Closes an ADO Recordset object. Many properties, such as CursorType and LockType, although read! write, cannot be modified while the recordset is open. The Close method must be invoked before those and other properties are modified.

Update and UpdateBatch methods—Update writes changes for the current record to the underlying data source; UpdateBatch writes pending changes for all modified records to the underlying data source. The UpdateBatch method is only relevant when Optimistic Batch Locking is used.

Cancel and CancelBatch methods—The Cancel method cancels modifications made to the current record; the CancelBatch method cancels pending changes to all modified records.

Resync method—Refreshes the Recordset object with data from the underlying data source. Invoking this method does not rerun the underlying command. Options exist for which records are actually refreshed.

Requery method—Unlike the Resync method, reruns the underlying command, which causes any pending changes to be lost. In effect, issuing a Requery is like invoking the Close method then immediately invoking the Open method.

Supports method—Specifies whether or not the recordset supports a function, based on a passed argument. For example, you can use this method to specify whether a recordset supports bookmarks, or the addition or deletion of records, or the Find, Update, and UpdateBatch methods, to name a few. Because what is supported is depends on the OLE DB provider used, it is a good idea to use this method to make sure a needed function is supported.

GetRows method—Returns a set of records into an array.
GetString method—Returns a set of records into a string.

The moral of the story is that before relying on the existence of anything in ADO, know and understand the OLE DB provider you are using, because the capabilities available to you can vary dramatically.

Lock types

There are four different locking schemes in ADO recordsets. These locking schemes are similar to those in Visual FoxPro.

Read-Only—As the name indicates, the recordset is opened for read-only purposes only. When you don’t need to modify data, this is the best locking scheme to use from a performance standpoint. This scheme applies to both server and client-side recordsets.

Lock Pessimistic—In this scheme, a lock attempt is attempted as soon as an edit is performed. This locking scheme is not relevant for client-side recordsets. Pessimistic Locking in an

Who’s Going to DevCon?

by Barty R. Lee

I recently read an editorial in the current issue of FoxTalk (March 2000) titled ‘Who’s Going to DevCon”. I believe there are a few clarifications that need to be made concerning this editorial and the apparent bias of its author, Whil Hentzen. I just feel compelled to respond. Following are some statements made in this editorial:

“Since then (the Palm Desert DevConJ, a second ‘VFP DevCon’ sponsored by Microsoft and the folks who handled registration at the last few VFP DevCons has been announced for the middle of May in New Orleans.”

Whil knows the “folks who handled registration at the last few VFP DevCons”, Tech Conferences (TCI), and he also knows that TCI handled more than just registration. TCI has been a full partner with Advisor Publications (now Advisor Media) since Advisor began having DevCons back in 1995. Advisor, with an assist from Microsoft, arranged for speakers and session content. TCI handled all of the conference logistics, not just registration. (Do we really have to go over this again, folks?) The last official event that TCI and Advisor partnered was the Palm Springs VFP conference in June, 1999. Regarding the “since then” implications, I can only say that discussions involving a second DevCon-type event, and its viability, had started with Microsoft before the Palm Springs event and continued while the event was going on. Before the conference had ended, it was decided that, yes, there would be another major developers conference in the year 2000. One other point needs to be mentioned here. The New Orleans (NOLA) event is being coproduced by three organizations, not one: Tech Conferences, Microendeavors (MEl), a well-respected and very well known training company, and Microcomputer Engineering Services (MES) - some of you might remember MES. . .they’re the sponsors of the Annual Southern California VFP conferences. Whil knew all of these details, including the dates of the NOLA conference (May 14-18), before sitting down to pen the editorial. But he seems to have selective memory on this one.

“The May New Orleans show is going to be a VFP 6.0 show. That means that the topics presented are going to be old news to many of you.... There’s a sister show in New Orleans covering SQL Server and there’s some sort of deal where the VFP conference attendees can attend SQL Server sessions as well.. ..being able to cherry pick both VFP and SQL Server sessions sounds like a bargain Miami, on the other hand, will be featuring Visual FoxPro 7.0. I personally never have gone to a show to learn in-depth concepts.... What! look for, instead, is guidance on the right approach and direction... Miami’s sessions on VFP 7.0 will not only cover tried and true techniques that worked in VFP 6.0 and earlier, but will prepare you for 7.0 and beyond.”

“Old news to many of you”? Let’s start off with a quote from one (Con’t, page 5)

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