DataRow[] and DataRow (C#)?

G

Gladimir

Well-known member
Joined
Mar 29, 2003
Messages
60
Location
San Diego, CA
Im having a little trouble getting with DataRows and DataRowCollections. The primary question is at the bottom of this post.

Here is a code snippet that is working well:

Code: 
// code is truncated for brevity;

DataRowCollection drcComputer = ds1.Tables["scsdComputer"].Rows;
foreach (DataRow row in drcComputer)
{
   // search for assetID from computer table in asset table
   string strrowSelect = "assetID = " + strassetID + "";
   DataRow[] foundRows = ds1.Tables["asset"].Select(strrowSelect);

   // if assetID does not exist in asset table, then add it
   if (foundRows.Length < 1)
   {
      // add new row
      DataRow newRow = ds1.Tables["asset"].NewRow();
      newRow["assetID"] = strassetID;
      ds1.Tables["asset"].Rows.Add(newRow);
   }
   else
   {
   // NOTE: this is where I am having problems
   }
}


The above code pulls assetID from the scsdComputers table and searches for it in the asset table. If the assetID is not found in the asset table, the assetID is added to the asset table in the if-block.

The trouble comes in the else-block. If the assetID does exist in the asset table, then I want to edit a value in the row returned by the Select method used one line above the if-block. However, I noticed there seems to be some difference between DataRow[] and DataRow, and that seems to be what I need to know.

I cannot add foundRows.BeginEdit() to my else-block because the BeginEdit method does not exist for DataRow[] foundRows. Do I have to create a new DataRowCollection and re-run my Select method in the else-block using DataRow?
 
DataRow[] would be an array of DataRow objects; you need to
specify an element in the array. So, if you want to edit the first row
that was found, you would call foundRows[0].BeginEdit();

If there were multiple rows returned by your query, and you want
to edit each one, then a foreach loop would do the trick.

C#: 
foreach (DataRow dr in foundRows) {
  dr.BeginEdit();
  // code
  dr.EndEdit();
}
 
Last edited by a moderator:
Thanks... One More...

Thanks, that worked!

Now I have another problem.

I am using OleDbCommandBuilder to automatically generate my update string when I do use the OleDbDataAdapter.Update method.

During my pass, I successfully add 7872 records to the asset table using the Adapter.Update with OleDbCommandBuilder. During a second pass, I load the existing 7872 records in DataSet ds1, add another 1846 new records to ds1, and attempt to update the source.

When I call the OleDbDataAdapter.Update method (still using OleDbCommandBuilder), I get a "string too long" error telling me I am trying to add too many records. Ive included a very basic code snippet below:

Code: 
// create dataset and populate with tables
DataSet ds1 = new DataSet();
ds1.Tables.Add("scsdComputer");
ds1.Tables.Add("asset");

// setup connection using my dbConnection class
dbConnection masterDb = new dbConnection();
OleDbConnection mdb = masterDb.m_mdb;

// create the adapter and command objects
OleDbDataAdapter scsdComputerAdapter = new OleDbDataAdapter(strscsdComputerSelect, mdb);
OleDbCommandBuilder scsdComputerCommand = new OleDbCommandBuilder(scsdComputerAdapter);
OleDbDataAdapter assetAdapter = new OleDbDataAdapter(strassetSelect, mdb);
OleDbCommandBuilder assetCommand = new OleDbCommandBuilder(assetAdapter);

// populate the tables in the dataset
scsdComputerAdapter.Fill(ds1, "scsdComputer");
assetAdapter.Fill(ds1, "asset");

try
{
   // do a bunch of stuff then update source
   scsdComputerAdapter.Update(ds1, "scsdComputer");
   assetAdapter.Update(ds1.GetChanges(), "asset");
}

The error is generated by the scsdComputerAdapter.Update line. Any ideas would be greatly appreciated.
 
I got it...

Ok, this was a case of the absent-minded professor.

The assetID field had a 10 character constraint on it, which was fine before I changed the rules about what I would accept as an assetID. Everything should work fine now.
 
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