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You are not looking at the problem from the right angle IMO.
The problem of changed DB schema is a separate problem (and a headache) altogether. You will need to write some kind of DB upgrade framework to solve upgrade issues and you will need to change existing data classes to incorporate new fields and (sometimes) eliminate obsolete ones.
What bothers me most is the impedance mismatch between the relational DB and the object oriented data classes. Here I spend lots of time writing boring repetitive and error prone data access code when most of it can be done automatically or eliminated altogether using tools like hibernate/nhibernate. This is where my biggest pain exists. This is where you'll end up if you are not careful enough.
I'd also recommend you stay away from tools that auto-generate classes based on DB schema. You should never design the DB schema first and than write classes to represent it. It should always work the other way around - do a well designed object model and than find the best DB modeling to represent this model. This is why I don't like tools like SubSonic and prefer tools like Hibernate.
If you have the choice I'd recommend using object oriented DB instead of a relational one (that is - if you don't need Oracle performance..). I've played some time with the db4o database and it looks pretty straight forward to work with. Such a database eliminates all the headache of writing data access code. You simply save and read whole class instances. Much much easier to work that way.
If I was not so stubborn when it comes to NOT using commercial libraries (I always prefer to work with open-source modules due to source code availability in case of errors) I would have probably saved tens to hundreds hours of wasted effort writing data access code to map from the relational DB model to object oriented classes.
Liron
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Does Oracle offer an OO solution? I saw a little bit on it but it seemed like it was still in it's early stages. I think I am going go with the db4o like you said but I have another question related to something I mentioned before. Basically I had 7000 line sof code going just because I had a very large object. Is that a problem?? It's just that I have an item that holds lot's of different types of data. It's patient data as you can imagine can get large.
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Oracle does not offer any OO solution that I know of.. Oracle is too heavily invested in relational technology to offer anything different.
With db4o you'll simply save the entire object with a single line of code. I don't think you'll have problem with that but maybe you'll need to find other things to do in your spare time (see a movie, play with kids, get a life  )
Good luck with your endeavor
Liron
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Hi all,
I have different characters in a string, My string may contain CHAR(10) or CHAR(13) + CHAR(10).
If my string contain only CHAR(10) then I want to replace it with CHAR(13) + CHAR(10). And if my string contain CHAR(13) + CHAR(10) then I don't want to replace it.
Can any body give me a solution to this.
Thanks & Regards
Mishra
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Find the characters in string like this...
DECLARE @position int, @string char(8)
-- Initialize the current position and the string variables.
SET @position = 1
SET @string = 'New Moon'
WHILE @position <= DATALENGTH(@string)
BEGIN
SELECT ASCII(SUBSTRING(@string, @position, 1)),
CHAR(ASCII(SUBSTRING(@string, @position, 1)))
SET @position = @position + 1
END
GO
You may modify/build a new string upon your requirements...
Please remember to rate helpful or unhelpful answers, it lets us and people reading the forums know if our answers are any good.
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We can do this in two cascaded steps:
1. Replace all occurrences of Char(10) with Char(13)+Char(10)
2. Replace all occurrences of Char(13)+Char(13)+Char(10) with Char(13)+Char(10)
Note that Step 1 replaces some unwanted occurrences also (i.e. Char(13)+Char(10) occurrences), but the second step fixes those unwanted wrong replaces.
Have fun with this piece of code:
declare @myTestString varchar(50)
set @myTestString = char(10)+char(13)+char(10)+char(10)+char(13)+char(13)+char(13)+char(10)
set @myTestString = replace( @myTestString, char(10), char(13)+char(10) )
set @myTestString = replace( @myTestString, char(13)+char(13)+char(10), char(13)+char(10) )
Cheers,
Syed Mehroz Alam
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Hi,
I hv a query which retrives the data frm data base and also calculates sm value for few colums i get the value as infinity.so how can i hv it in my query so that it should display zero and find the sum of that column.
Here is my query...Pls sm one help...
OleDbCommand cmdMtdDays = new OleDbCommand("with member COSt as sum({[Dimension Time].[Day Text].[" + FromFilter + "]},[Measures].[Out Standing Amt]) member AV_MTD as sum(" + QueryFilterMTD + ",[Measures].[Inv Amt]) member COSMTD as (AV_MTD/" + day + ") member MTDDAYS as (iif(COSt=0,null,(COSt/COSMTD))) select {MTDDAYS} on columns, nonempty([DLOMAS].[OMVALU].[OMVALU]) on rows from COS", con);
Regards,
Annu
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Already answered in another forum
Please remember to rate helpful or unhelpful answers, it lets us and people reading the forums know if our answers are any good.
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HI
I have a table (ContactDetails) with 2000 records. I have an application receiving an XML file from an external web service. Most time the data received from the web service is similar to the data in my table. Occasionally the data returned from the web service will have few differences. I want to compare the data received from the web service with the data in my local database and generate a xml file (based on the same schema) to send to another application . So how do i go about doing that?
Thanks
modified on Thursday, August 28, 2008 12:13 PM
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I would approach this problem by breaking it down into phases.
1) Read the XML file
2) Fetch data from the database and compare to XML data
3) Write a resulting XML file
Below should get you some idea how to loop through an XML file.
<br />
Imports System.Xml<br />
<br />
Dim xdTemplate As New XmlDocument<br />
Dim xnRoot As XmlNode<br />
<br />
xdTemplate.Load("c:\temp\FP_TAK.xml")<br />
<br />
xnRoot = xdTemplate.SelectSingleNode("/myPath/mySub/etc")<br />
<br />
' This code show some simple code to loop through an XML file<br />
' you will need to modify this based on your layout, but at least it shows some<br />
' functionality.<br />
<br />
While (Not (IsNothing(xnRoot))<br />
If (xnRoot.Name = "FSFORMULATPALL") Then<br />
If (xnRoot.Item("PARAM_CODE").InnerText = "R.B.D_SOY_ALLERGEN") Then<br />
Debug.Print(CStr(i) + ") " + xnRoot.Item("PARAM_CODE").InnerText)<br />
xnRoot.Item("PVALUE_LABEL").InnerText = "No"<br />
End If<br />
End If<br />
<br />
xnRoot = xnRoot.NextSibling<br />
End While<br />
<br />
xdTemplate.Save("c:\temp\dave.xml")<br />
<br />
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Hello every one
I have created small application which can save and delete images from sql database it's works fine but only problem is when ever I add or delete image from sql database it dosent refresh I mean If I delete on image so in picture or database count it should show that database is empty or if there is two images in database then it should shows that one image in database
but if i close application and restart it then it shows all the changes so could you please help me with this
this is the code for save,delete and load image
Private Sub LoadImages()
Try
conImage = GetDBConnection()
dsImage.Clear()
Me.ImagesTableAdapter.ClearBeforeFill = True
Me.ImagesTableAdapter.Fill(Me.dsImage.Images)
daImage.Fill(dsImage, "Images")
Catch ex As Exception
MsgBox(ex.Message)
End Try
conImage.Close()
conImage.Dispose()
End Sub
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
'get sql connection
Try
conImage = GetDBConnection()
Dim sSQL As String = "INSERT INTO Images (Pic,Title, IType, Height, Width) VALUES(" & _
"@pic, @title, @itype, @iheight, @iwidth)"
commImage = New Data.SqlClient.SqlCommand(sSQL, conImage)
Call GetImage()
commImage.ExecuteNonQuery()
MessageBox.Show("Image successfuly saved in database", "Image Load")
Catch ex As Exception
MsgBox(ex.Message)
End Try
commImage.Dispose()
' commImage = Nothing
conImage.Close()
conImage.Dispose()
Call LoadImages()
End Sub
Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
SelectedImage = ("DELETE FROM Images WHERE ImageID = " & txtImageFile.Text)
conImage = GetDBConnection()
Try
commImage = New Data.SqlClient.SqlCommand(SelectedImage, conImage)
commImage.ExecuteNonQuery()
MsgBox("Image successfuly deleted from database", MsgBoxStyle.Information)
Catch ex As Exception
MsgBox(ex.Message)
End Try
commImage.Dispose()
commImage = Nothing
conImage.Close()
conImage.Dispose()
Call LoadImages()
End Sub
please help me with this issue 
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Hi,
Is the row really being deleted: Modify the following to see that one record is really being deleted
SelectedImage = ("DELETE FROM Images WHERE ImageID = " & txtImageFile.Text)
conImage = GetDBConnection()
Try
commImage = New Data.SqlClient.SqlCommand(SelectedImage, conImage)
recordsAffected = commImage.ExecuteNonQuery()
MsgBox("Deleted count: " & recordsAffected)
MsgBox("Image successfuly deleted from database", MsgBoxStyle.Information)
If recordsAffected is 0 then your condition isn't correct
Mika
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Hello Mika
first of all thanks for your rep.
yes it's shows affected records so i have dont this
Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
Dim RecordAffected As Integer
SelectedImage = ("DELETE FROM Images WHERE ImageID = " & txtImageFile.Text)
conImage = GetDBConnection()
Try
commImage = New Data.SqlClient.SqlCommand(SelectedImage, conImage)
RecordAffected = commImage.ExecuteNonQuery()
MsgBox(CStr(RecordAffected) & " Image successfuly deleted from database", MsgBoxStyle.Information)
Catch ex As Exception
MsgBox(ex.Message)
End Try
commImage.Dispose()
commImage = Nothing
conImage.Close()
conImage.Dispose()
Call LoadImages()
End Sub
but still same after deleting record from sql database I have open "Show Data Table" and check that record has been deleted so i dont know what to do but if i close application and rerun it it shows the changes on screen
waiting for your kind rep.
have a nice day
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Okay, was the RecordAffected 1 or 0?
Another thing, if I understood correctly the record is deleted when you close and rerun the application. What does your connection string look like? Could you post the GetDBConnection method? What I'm thinking of is that you have a pending transaction if the record is deleted, but you cannot see thet the deletion has happened.
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Hello again
thanks for your rep.
Private Function GetDBConnection()
' Compose the database file name.
' Modify this if the database is somewhere else.
Dim DBname As String = Application.StartupPath()
DBname = DBname.Substring(0, DBname.LastIndexOf("\bin"))
DBname = DBname & "\Images.mdf"
' Compose the connect string.
Dim connect_string As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=" & _
DBname & ";Integrated Security=True;User Instance=True"
' Open a database connection.
Dim SqlConn As New Data.SqlClient.SqlConnection(connect_string)
SqlConn.Open()
' Return the connection.
Return SqlConn
End Function
well in the message box it says record 1 as bellow
RecordAffected = commImage.ExecuteNonQuery()
MsgBox(CStr(RecordAffected) & "Image successfuly deleted from database", MsgBoxStyle.Information)
i set a brakpoint and stepin so variable RecordAddected was 1
waiting for your kind rep.
thanks again
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When you run the application and delete the image, open Task Manager and go to processes tab. How many sqlservr processes you see?
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Hello again
Thanks for your promt rep.
yes I have delete one image and i can see as bellow
1- sqlbrowser.exe -- 652k
2- sqlservr.exe --- 25540k
3- sqlservr.exe -- 5900k
4- msftesql.exe --1724k
5- sqlservr.exe ---54084k
this is what i can see in task manager
waiting for your kind rep.
thanks
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You have two SQL Server instances running at the same time. I don't know if they are separate databases, but in worst case they are separate user instances of the same database (you had User Instance=true in your connection string).
Instead of getting a new connection to the db in every sub, try to change the logic so that you get the connection only once. For example create the connection when the window loads and use that connection in every sub. Does anything change?
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hello again
thanks for promt rep.
well to be very honest I have just started sql so i am not expert but as you said I will try to change logic and let you know
what I understand according to you that I need to open connection when form load and but do I need to close it or not but upto now what i have learnt i have to close the connection but i will see how it goes
is it possible to help me with this logic that where to start i dont want answer i will try it
waiting for your kind rep.
have a nice time
thanks
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No problem,
Perhaps the easiest way is to make the connection static so that every time you connect to the database, you get the same connection. Something like (may contain errors):
Private Function GetDBConnection()
Static SqlConn = Nothing
If SqlConn Is Nothing Then
' Compose the database file name.
' Modify this if the database is somewhere else.
Dim DBname As String = Application.StartupPath()
DBname = DBname.Substring(0, DBname.LastIndexOf("\bin"))
DBname = DBname & "\Images.mdf"
' Compose the connect string.
Dim connect_string As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=" & _
DBname & ";Integrated Security=True;User Instance=True"
' Open a database connection.
SqlConn = New Data.SqlClient.SqlConnection(connect_string)
SqlConn.Open()
End If
' Return the connection.
Return SqlConn
End Function
And when using this, don't close and don't dispose the connection, so comment the lines conImage.Close() and conImage.Dispose() in btnDelete_Click and LoadImages and btnSave_Click
The idea is to test that you are using the same database all the time. If this doesn't help then we change back to the original logic and try something else.
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Hello sir
thanks for promt rep.
yes i have change the logic the way you said but still it's same problem i mean i can save or delete image from sql database but i have to close application to see the changes
and one more thing i would like to tell you that i have created another application without image but it works fine if i add or delete first name and last name it shows the changes same time and i have used same method with this application but i am not sure but i sow one difference in it
that project has one table with three columns ID, FirstName, LastName
and this is button event to change enable = false
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Button2.Enabled = False
Button3.Enabled = False : Button4.Enabled = False : Button5.Enabled = False
Button1.Enabled = True
TextBox1.Enabled = True : TextBox2.Enabled = True
TextBox1.BackColor = Color.Aquamarine : TextBox2.BackColor = Color.Aquamarine
Try
Me.StudentBindingSource.EndEdit()
Me.StudentBindingSource.AddNew()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
but with this there is only one difference
Me.StudentBindingSource.EndEdit()
Me.StudentBindingSource.AddNew()
so do you think this is the issue
waiting for your kind rep.
have a nice time
thanks again
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If you have corresponding BeginInit somewhere, you should call EndInit. Trying that is a good idea.
Also one possibility is that even if you delete the image from database, it isn't correctly refreshed in the dataset (dsImage). However you do call Clear-method so it should work.
If calling EndInit doesn't help, can you re-create the dataset (set dsImage to Nothing and create a new dsImage) and fill it after that.
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hello again
as you said that to refresh dsimage so for example if there is 4 images in database and if i delete image no 3 so after deleting image it's refreshing dataset because in picture box it shows first image but still you can go forward or backword up to image 4 but when i close application and rerun it then it shows 3 images in database so that means it refreshing dataset properly
and there is no corresponding in begininit at all so i think i dont need to endinit
so we have only last option so i think i will try tomorrow
but any way i learn lot from you i realy appriciate that
thanks a lot
if i need any help i will contact you tomorrow
good night
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You're welcome.
I'll go and have some sleep also... 
One thing you can try tomorrow is to add AcceptChanges()- call to dataset after deletion or fill. In case that the record is deleted but changes are still pending
MIka
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Hello sir
good morning
how are you
I have tried every thing but still it's same problem so now I don't know what to do
I have also tried AcceptChanges() but still it's same
waiting for your kind rep.
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