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The LA Fox Developer Newsletter
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March 2000
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If you missed the Windows 2000 Conference in San Francisco, you can experience it right here in Southern California! This one day conference includes twelve sessions providing in-depth Windows 2000 technical information focusing on deploying reliable infrastructure, how to make it easier to use and manage desktops and servers, and building E-Commerce digital business solutions. Special Hands-On theaters will be available all day so you can test-drive Windows 2000.
Sessions will be presented by Microsoft Systems Engineers as well as Microsoft Business Partners
The cost for this unique event is $79 per attendee. Attendees will receive the Microsoft Certified Systems Engineer Training Kit
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Upgrading to Windows 2000, Tech Net IT Guide to Windows 2000, and Windows 2000 Interactive Computer Based Training CD. Attendees will also be entered to win many exciting prizes including Windows 2000 Professional, Windows 2000 Server, Office 2000 and others!
Anaheim Hilton
777 Convention Way
Anaheim, CA 92802
For more information on agenda and detailed breakout descriptions, please visit
www.microsoft.com/socal/windows2000/ deploy.
Please visit
www.microsoft.com/socal/windows2000/deploy to
register online or call 800-344-8963. Register today as space is limited.
ADO
Jumpstart
(Con’t from page 4)
ADO recordset is like Pessimistic Locking with Row Buffering in a Visual FoxPro cursor.
Lock Optimistic—In this scheme, a lock attempt is made when the Update method is invoked. This locking scheme applies to both server and client-side recordsets. Optimistic Locking in an ADO recordset is like Optimistic Locking with Row Buffering in a Visual FoxPro cursor.
Lock Batch Optimistic
—
This scheme is like the Lock Optimis
tic
scheme, except that more than one row of data is involved. In this scheme, a lock is attempted on modified records when the UpdateBatch method is invoked. This scheme is like Optimistic Locking with Table Buffering in a Visual FoxPro cursor.
The following table illustrates the availability of some common
(Con’t, next column) |
methods depending on the locking scheme used:
Table 3. Method Availability (Depending on Lock Type)
With the concepts of cursor types, locations, and locking schemes out of the way, we can discuss the real abilities of ADO recordsets. The most notable of these abilities are updating, sorting, and filtering of data. Before undertaking that discussion, however, take a few moments to review the Fields Collection object.
Fields collection object
Associated with the Recordset object, is the Fields Collection object. The Fields Collection object contains zero or more Field objects. The following code enumerates through the Fields Collection of a Recordset object:
For Each ofleld In oRecordset.Fields
With oField
?.Name,.Value,.Type,.DefinedSize
?.ActualSlze,.NumericScale,.Precision
End
With
Next oField
The common Field properties you will work with:
Name—Specifies the name of the Field object. This corresponds to the name of the data element in the underlying data source. It is easy to define the name element as the name of the field in the underlying table. However, note that ADO and OLE DB work with both relational and nonrelational data. Given that, while you may be working with ADO, the underlying data may come from Outlook, Excel, Word, or Windows NT® Directory Services.
Value-Indicates the current value of the Field object.
OnginalValue—Indicates the Value property of the Field object before any modifications where made. The OnginalValue property returns the same value that would be returned by the Old Val(
)
function in Visual FoxPro. When you invoke the Cancel or CancetUpdate methods of the Recordset object, the Value property of the Field object is replaced by the contents of the OriginalValue property. This behavior is similar to that exhibited when TableRevert(
)
is issued against a Visual FoxPro cursor.
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