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 can-

cels 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 sup-

ports 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

(Con’t, page 6)

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 co-

produced 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 ses-

sions 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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