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I have three tables, a main table and two subtables that are related to the main table by the main tables key field. In my application I set up three OleDbDataAdapters to read three seperate tables into three tables of a dataset and then I add to the datasets relation collection to link the tables together. The problem is that while I can update the main table by calling the update method of it's DataAdapter, I can't do the same with the other two tables. When I call their update method, nothing happens. I get no errors and the rows that where marked to be updated are still marked to be updated (i.e. AcceptChanges hasn't been called). Also, I can't change the key field even in the main table. Changes to the key simply get ignored and don't get written back to the database. Does anybody know what is happening here? I suspect it's something to do with the tables being related.
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Please show your code which updates the Child Tables.
Stefan
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Okay, thanks for your reply. Here's an example of the problem I'm having. I've included some of the code I've added just to try and figure out what's happening. When I iterate throw the rows of the child table I find that all the rows have RowState = Unchanged, even though some of them have an Original and a Proposed value. I believe they are not getting updated because the RowState is Unchanged, but I can't figure out why the RowState is Unchanged when there is clearly a Proposed value available. Surely setting a Proposed value for a row should automatically change the RowState?
<br />
public void UpdateData()<br />
{<br />
connDB.Open();<br />
SubApt.RowUpdating += new OleDbRowUpdatingEventHandler(MyRowUpdateHandler);<br />
<br />
string s = "";<br />
foreach (DataRow thisRow in m_myDS.Tables["tblSub"].Rows)<br />
{<br />
s += thisRow["Key"] + " -> " + thisRow["Field1"] + " " + thisRow.RowState.ToString() + "\n";<br />
if (thisRow.HasVersion(DataRowVersion.Proposed))<br />
{<br />
s += thisRow["Field1", DataRowVersion.Original] + " " + thisRow["Field1", DataRowVersion.Proposed] + "\n";<br />
}<br />
}<br />
MessageBox.Show(s);<br />
<br />
MainApt.Update(m_myDS.Tables["tblMain"]);<br />
SubApt.Update(m_myDS.Tables["tblSub"]);<br />
connDB.Close();<br />
}<br />
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1. Did you call AcceptChanges somewhere? Don't call AcceptChanges before Adap.Update().
2. Clear the EventHandler for RowUpdate. This may call AcceptChanges()
3. Try to edit a Row and immediatly afterwards check it's RowState. If the RowState is unchanged I don't know what's wrong. AcceptChanges is a tricky thing: after this call all Rows are marked unchanged! So there is nothing what could be Updated by the Update Method of Apt.
Please inform me about Point 3.
Stefan
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STW wrote:
1. Did you call AcceptChanges somewhere? Don't call AcceptChanges before Adap.Update().
No, I have not called AcceptChanges explictly anywhere in my program. I had thought that perhaps calling update on the main table might automatically call AcceptChanges on the child table, but not updating the main table didn't fix the problem. I was also thinking that calling AcceptChanges should move the proposed value into the original value shouldn't it? That's not been happening.
STW wrote:
2. Clear the EventHandler for RowUpdate. This may call AcceptChanges()
I tried it without the EventHandler and it makes no difference. I only put the EventHandler there in the hopes of being able to intercept the call and figure out what was happening. As it turns out, the event never gets fired.
STW wrote:
3. Try to edit a Row and immediatly afterwards check it's RowState. If the RowState is unchanged I don't know what's wrong. AcceptChanges is a tricky thing: after this call all Rows are marked unchanged! So there is nothing what could be Updated by the Update Method of Apt.
Okay, I tried manually changing the value of one field in the child table like this:
<br />
m_myDS.Tables["subtable"].Rows[0]["Field1"] = 101;<br />
And if I then iterate through the rows in the table, I can see that row has been changed to RowState.Modified and it doesn't have a proposed value anymore. Further, when I call the update that row does, in fact, get updated in the database.
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Okay, I just figured something out. If, while I'm iterating through the rows, I call EndEdit on each row it will set the RowState to modified (if it has actually been modified). So the problem seem to be that when a datarow is bound to my form, BeginEdit is implicitly called, and when that particular row becomes unbound, it should automatically call EndEdit on that row. But it isn't doing it for my child table. Now, I don't want to have to iterate through all my records and call EndEdit on every one of them before I run my update because I have a lot of records and I expect it to grow rapidly once (if) I finish my app. I'm thinking I could intercept the PositionChanged event of my CurrencyManager, but I think at that point the position has already changed so I won't be able to grab the previous row to call EndEdit on it. I could try and intercept every button or event that results in a change of position and call EndEdit before I change the position, but that's a pain since I'd have to remember to do that in several different places. I'd also have to make sure I call EndEdit on the current row when the Update button is clicked, but that's not a major problem (because it's only one place).
So I think I can work around my problem, but I'd be much happier if I could just figure out why the CurrencyManager isn't calling EndEdit and fix it!
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I am getting an error msg:
"The conversion of char data type to smalldatetime data type resulted in an out-of-range smalldatetime value."
when I have the following code in where close:
and n.dateentered between (case
When DatePart (dw , getdate())=2 Then (getDate()-3 )
When DatePart (dw , getdate())=4 Then (getDate()-2 )
When DatePart (dw , getdate())=6 Then (getDate()-2 )
Else GetDate() End ) and (getdate()-1)
but when I run with this (I put dates manually) it is fine.
and n.dateentered between '09/20/2003' and '09/29/2003'
Any idea why?
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I have tested the SQL query using SQL Server Enterprise Manager and it's working fine for me.
My guess is that n.dateentered is of type "smalldatetime" and GetDate actually returns "datetime" instead.
You might want to try one of the following:
1. Use CAST(x as y) e.g. CAST( (case when...end) AS smalldatetime) ->I've tested this with the code and it works
2. Use DateAdd() function instead of getDate()-3
3. Use DatePart to format your date ranges to yyyymmdd format
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code for adding a new record,deleting a record that already exists and modifying an existing record needed in C++
ranjani
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Is there a way to get the actual SQL commands that the OleDbDataAdapter.Update method is passing? I'm having a problem due to the fact that every time I try and run my Update command, I get an exception thrown by the db (access) claiming that there is a syntax error in my SQL command. Trouble is I can't seem to figure out how to get the actual text of the command (after the adapter has filled in the parameters). I'm pretty confident that the command that I set as the Update command is okay, so I want to see if the problem is with how the adapter has decided to fill in the parameters?
I tried hooking the RowUpdating event, but I still only get the command text without the parameters inserted?
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The Update Command is an OleDBCommand. You can get the property CommandText from it...;)
Free your mind...
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But the CommandText only has the command before the parameters have been filled in. I need the actual command that is sent to the database when I call the Update method of my OleDbDataAdapter. Is there a way to get this?
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Okay, I tracked down the problem by systematically removing fields from my Update statement. The problem is caused by a date field. I have something like this (but with a lot more fields):
<br />
SQLUpdate = "UPDATE myTable SET Field1 = @Field1, Date = @Date, WHERE Key = @Key";<br />
Then I have this:
<br />
OleDbCommand myCmd = new OleDbCommand(SQLUpdate,myConnection);<br />
myCmd.Parameters.Add("@Field1", OleDbType.VarWChar, 20, "Field1");<br />
myCmd.Parameters.Add("@Date", OleDbType.Date, 0, "Date");<br />
<br />
myApt.UpdateCommand = myCmd;<br />
What's the right way to handle the date field in an Access database. Even the command builder seems to fail at this!! BTW, the Date field is bound to a DatePicker control on my form, perhaps something is getting lost in the translation?
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I've written a program that uses MS DataGrid Control, but i've got problems with running it on computers without MS Visual Studio. I have registered msdatgrd.ocx, but when i try to run my app i get the error message "cannot initialise data bindings". What else should i install?
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You need to make sure the target machine has COMCAT.DLL, MSSTDFMT.DLL and MSDATGRD.OCX, as well as any necessary database components.
Steve S
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Does anyone knows how to extract the value of a query using FOR XML ??
All I want to do is assign the result value into a variable.
Thanks 
Free your mind...
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It basically comes out as a set of string fields.
If using classic ADO, use a Recordset to capture it. If using ADO.NET, use a SqlDataReader.
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I know it works fine in the middle tier code. I just want to leave the result in the data tier (SQL Server). What I'm trying to do is a kind of audit trail, so when users update a record, I can take a snapshot of it (FOR XML RAW) and write it to another table.
Free your mind...
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Hello all,
A quick question, I’m working on designing a SQL (7.0) database and for 37 of the tables I have 2 fields that are common between them and I’m using these 2 fields as the primary key for the 37 tables and also as the Foreign key to define the relations between these tables.
For example: <br />
Project_ID1: part of the Primary Key<br />
Project_ID2: part of the Primary key<br />
Both of them together form the primary key for the 37 tables because they are the only unique fields within each table. And when I create a relation between 2 of the tables I use these same 2 fields as the foreign keys
So, I would just like to get your opinion on if that is a correct design or not, I had some people telling me that this is a poor design?
Thanks in advance
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I didn't really understand right.
Questions:
1. These 37 Tables do they all have the same Fields or what is different between them.
2. Do you store different Projects in different Tables?
3. Just show me the first 4 Fields of two Tables that I can understand.
4. What is the relation between the Tables?
Database Design is more difficult than many people think. A good structure may help the developers.
Please tell me more.
Stefan
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confusedconfused:Can anybody suggest some online tutorials for ADO.Net? I've gone through several but they all tell you how to connect to a database, download the info and then Console.WriteLine() the results.
but i want some more realistic..In real world application we need to work with the results in datasets. Getting into the detail of evaluating data within the tables/datasets to determine what changes have been made?
Taking a subset of one of the tables and creating a new table and returning only that.
Just wondering if anybody can suggest some online tutorials.
phani.
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This[^] may be helpful.
"Some people are like Slinkies... not really good for anything,
but you still can't help but smile when you see one
tumble down the stairs."
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Hi,
I need to generate menus at runtime for a sample Windows application. I'm using vs.net winforms with c#.
Every user in the application does not have access to all menu options, so the menu items being displayed is as per user login.
I need to generate the form code at run-time. Any info you can provide OR links about this particular topic will be very helpful and appreciated with a zillion thanx...
It seems i need to following at runtime...
1) Retrieve data from the sql database about the menu options available to the current user
2) Declare each Menu item
private System.Windows.Forms.MainMenu mainMenu1;
private System.Windows.Forms.MenuItem menuItem1;
...
2) Initialize each menu item
this.mainMenu1 = new System.Windows.Forms.MainMenu();
this.menuItem1 = new System.Windows.Forms.MenuItem();
...
3) Declare Menu Collections - add list of menuitems
this.mainMenu1.MenuItems.AddRange(new
System.Windows.Forms.MenuItem[] {
this.menuItem1,
this.menuItem5});
...
4) Define each Menu Item
i.e. specify Index, Shortcut Key, Text (with hotkey) and declare eventhandler for each Menu item
this.menuItem2.Index = 0;
this.menuItem2.Shortcut=
System.Windows.Forms.Shortcut.CtrlN;
this.menuItem2.Text = "&New";
this.menuItem12.Click += new System.EventHandler(this.menuItem12_Click);
5) Assign the menu to Form as the current menu
this.Menu= mainMenu1;
Hope u guys will be keen to help. Thanx in advance.
Sunny.
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What I usually do, is build the whole menu in the application. Then, when the user login in the application, I get an arraylist with all the menu options. After that, I execute a loop on the array list, and turn of all the options the user doesn't have access.
May be that could help you
Free your mind...
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Hi Guillermo,
Thanx for your post. Your method seems to make much, much more sense than what i was trying to do. I just checked out the help files - i can either disable a menuitem or hide it completely.
>> menuitem3.enabled=false; // to disable a menuitem
>> menuitem3.Visible=false; // to hide a menuitem
I'll try out your method. Hope u can guide me, if i get stuck somewhere. Thanx a lot again.
Sunny
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