Re: A couple of questions about updating data through a dataset
- From: "Rod" <rodf@xxxxxxxxxxxxxxxxx>
- Date: Thu, 16 Jun 2005 10:51:10 -0600
Thank you, W.G. for replying. My reply is in-line (towards the bottom):
"W.G. Ryan eMVP" <WilliamRyan@xxxxxxxxx> wrote in message
news:uPGOixfcFHA.720@xxxxxxxxxxxxxxxxxxxxxxx
>> DataRow r = DataTable.Rows[0];
>>
>> and the row has a column named FirstName, can I do this:
>>
>> r["FirstName"] = "Rod";
>>
>> or do I have to do something like this first:
>>
>> r.BeginEdit();
>> r["FirstName"] = "Rod";
>>
>> And if I do have to use the BeginEdit() method, do I also have to issue
>> the EndEdit() method? Or will that basically clear the row's Current
>> view and reassign that to the Original view?
>
> If you are doing this programatically, then no you don't. THe problme is
> that when you use the UI, often it will start the beginedit but nothing
> triggers the end edit. HOwever, I'd highly recommed that you do use
> beginedit. If you don't, then for instance, if your values are sorted, it
> could affect the sort immediately.
>
>>
>> I know that the datarow's SourceVersion will come into play, but I am not
>> sure how.
>>
>> Second question: What DOES the Update() method of the SqlDataAdapter
>> really work on? For example, after struggling with this for half the day
>> I finally got rid of the error message I was getting saying,
>>
>> "Procedure 'spMyProc' expects parameter '@FirstName', which was not
>> supplied"
>>
>> to go away, but now when I assign a value to the datarow's FirstName
>> column, then I would have expected that to actually be saved to the
>> database when I issued the SqlDataAdapter's Update() method. Instead, it
>> just quietly goes about its business and nothing at all is saved/updated.
>> So, what I am doing wrong now?
>>
>> Rod
>
> Update goes through each row and looks at the RowState. If it's modified,
> added, deleted, then it looks to the corresponding command and fires it.
> If you look at the overload for a dataColumn DataColumn dc = new
> DataColumn("ColumnName", typeof(Whatever), Column). This is the value
> that will map back to the parameter if you've coded your CRUD correctly or
> of you had it generated. IF you don't have any changeds, you can call
> Update all year and nothing will happen. If you call Update and you have
> modified rows but no update command, you'll get an exception. It maps
> those values back to the params.
>
> Does this answer your question?
Almost. I will modify a column in the dataset, but then when I call the
Update() method of the SqlDataAdapter it doesn't save/change anything. I
don't understand how I could modify the value but then the Update() not
work.
BTW, I am doing this programmatically, rather than using any wizard like the
CommandBuilder.
> BTW< I'd highly encourage using a Keyed table, and using the DataAdapter
> Configuration wizard and deconstructing what it created. You'll learn a
> lot - or at least, I did.
>
> --
> W.G. Ryan, MVP
>
.
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