The LA Fox Developer Newsletter

ADO J urn psta rt (Cony from page 3)

cChars =

For nDigit = I To Len(cBin)

nBin = Asc(Substr(cBin, nDigit, 1))

cChars = cChars + Thls.Hex2Char(Int(nBinhl6)) +

This.Hex2Char(Mod(nBin,16))

EndFor

Return(cChars)

EndProc

Protected Procedure hex2char(nHex)

*/

This method converts a hex value to ASCII

Local nAsc

Do Case

Case Between(nHex,0,9)

nAsc =48 + nHex

Case Between(nHex,10,15)

nAsc = 65 + nHex - 10

EndCase

Return(Chr(nAsc))

EndProc

Procedure import(cString)

*/

This method takes the binary string and populates the 4 data

*/

properties

With This

.Datal = Left(cString, Len(.Datal))

cStrlng = SubStr(cStrlng, Len(.Datal)+1)

.Data2 = Left(cString, Len(.Data2))

cStrlng = SubStr(cString, Len(.Data2)+1)

.Data3 = Left(cString, Len(.Data3))

cString = SubStr(cString, Len(.Data3)+1)

.Data4 = Left(cString, Len(.Data4))

EndWith

Return cString

EndProc

Protected Procedure export

*/

This method creates the buffer to pass to the GUID API.

With This

.Datal = Space(4)

.Data2 = Space(2)

.Data3 = Space(2)

.Data4 = Space(8)

End With

Return(This.Datal + This.Data2 + This.Data3 + This.Data4)

EndProc

Protected Procedure Convert(cGuid)

•I This method makes the call to the BinToHex that

*/

converts the data in the 4 data properties from

With This

cGuid = .BinToHex(.Datal) + “-“ + .BinToHex(.Data2) + “-“

May 2000

.BlnToHex(.Data3) + “-“ + .BlnToHex(.Data4)

Return cGuid

Endwith

EndProc

Procedure Init

*/

Declare the function In the DLL

Declare Integer UuidCreate

In c:\Winnt\System32\RPCRT4.DLL String @ UUID

Return

EndProc

EndDefine

Output is produced as follows:

Disconnected/Persisted Recordsets

One of the most powerful features of ADO is the ability to create

both disconnected and persisted recordsets. A disconnected

recordset is a client-side recordset that does not have a current

ActiveConnection. SQL data sources, such as SQL Server,

Oracle, and so on, are licensed according to the number of

concurrent connections. For example, the number of people that

using an application connected to SQL Server is 300. However,

it has been determined that at any time, only 50 users actually

use the services of a connection. A connection is needed only

when data is being requested, updates are made, or a stored

procedure on the database server is invoked. From a financial

standpoint, it is far less expensive for a company to only

purchase 50 licenses than to purchase 300. From a resource

standpoint, performance should improve because the server only

has the overhead of 50 connections instead of 300, of which 250

are idle at any time.

Using the ADO recordset of customer data already created, the

following code disconnects the client-side recordset:

oRecordSet.ActiveConnection = Null

If you attempt to do this with a server-side recordset, an error

occurs stating that the operation is not allowed on an open

recordset. Once the recordset is disconnected, you can con-

tinue to work with and modify records. The following code will

work:

oRecordset.MoveFirst

Do While loRecordset.Eof

?oRecordset. FieIds(”companyname”).Value

oRecordset.Fields(”companyname”).Value =

Upper(oRecordset.FieIds(”companyname”).Value)

oRecordset.MoveNext

EndDo

With modified records in a client-side recordset, three basic

options exist.

(Con ‘t, page 5)

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