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July 23rd, 2012, 04:06 AM
#1
Concurrency/Consistency Managing in VB6
Dear Pros,
Im a Visual Basic Programmer with experience of about 12 years. I do my application using VB as front end and Oracle as back end. However, i had never deployed in a highly concurrent enivironment where many users use the application at the same time. I am in the process of implementing but have got challenges as the application keep on throwing errors and not completing the transactions. The following are the Errors that are frequently thrown which i suspect are as a result of Concurrency request:
"cannot update row as the data in the database has changed"
"cannot delete row as data in the database has changed"
This is how im connecting to my DB
If RsCoin.State = 1 Then
RsCoin.Close
End If
CmdCoin = "SELECT * FROM COINAGER WHERE ACCNO='" & CoinSt & "'"
RsCoin.Open CmdCoin, ConACExp, adOpenStatic, adLockOptimistic
RsCoin is a recordset
Can somebody assist me how to solve this problem?
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July 23rd, 2012, 05:35 AM
#2
Re: Concurrency/Consistency Managing in VB6
where are you getting the following error ?
"cannot update row as the data in the database has changed"
"cannot delete row as data in the database has changed"
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July 23rd, 2012, 06:18 AM
#3
Re: Concurrency/Consistency Managing in VB6
I am getting the error at a point of updating.
RsCoin.update
Soo many users are updating that table. its a banking environment.
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July 23rd, 2012, 06:26 AM
#4
Re: Concurrency/Consistency Managing in VB6
Can you post the Sub where the Code that error occurs... And Please use Code Tags...
[code] Your Code [/code]...
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July 23rd, 2012, 08:55 AM
#5
Re: Concurrency/Consistency Managing in VB6
Code:
Public Sub Create_TransactionID()
'On Error Resume Next
Dim SavedDate, CurrDateNo
'Creating Absence ID
If RsRef.EOF = False Then
RsRef.MoveLast
SavedAbid = RsRef!TRANSREF
SavedDate = RsRef!TRANSREF
RsRef.Delete 'So that we only have one serial at ago 'Added on 12/11/07
RsRef.Requery
RsRef.AddNew
DateSt = Now
If Len(SavedDate) = 8 Then
SavedDate = Mid(SavedAbid, 1, 8)
Else
SavedDate = SavedDate
End If
Call Convert_DateTo_Number
CurrDateNo = Mwaka & Mwezi & Enyanga
' If SavedDate = CurrDateNo Then 'silenced 15032010
If Left(SavedAbid, 8) = CurrDateNo Then
Katikati = Mid(SavedAbid, 9, 1000)
Katikati = Katikati + 1
Else
Katikati = "0"
End If
Absid = Mwaka & Mwezi & Enyanga & Katikati
RsRef!TRANSREF = Absid
RsRef.Update 'Here error occurs
Else
DabID.AddNew
Katikati = "0"
DateSt = Now
Call Convert_DateTo_Number
Absid = Mwaka & Mwezi & Enyanga & Katikati
RsRef!TRANSREF = Absid
RsRef.Update
End If
If TranT = "Deposit" Then
Absid = "DP" & Absid
Else
If TranT = "Withdrawal" Then
Absid = "WR" & Absid
Else
If TranT = "OC" Then
Absid = "OC" & Absid
Else
If SharesT = True Then
Absid = "SH" & Absid
Else
If Loan = True Then
Absid = "LN" & Absid
Else
If MpesaT = True Then
Absid = "MP" & Absid
Else
If IntProc = True Then
Absid = "IN" & Absid
If Treasury = True Then
Absid = "TR" & Absid
End If
End If
End If
End If
End If
End If
End If
End If
End Sub
Last edited by GremlinSA; July 23rd, 2012 at 09:34 AM.
Reason: PLEASE USE CODE TAGS..
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July 23rd, 2012, 10:08 AM
#6
Re: Concurrency/Consistency Managing in VB6
In a multi user environment you should move away from the rs.update and use a sql query to insert, update or delete instead.
I think that should slove the issue, I ran into something similar in the past where I had heavy traffic inserting data and the SQL Insert was flawless where rs.update failed with an error often.
Always use [code][/code] tags when posting code.
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