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DataAdapter Concurrency violation
Posted by: Gal Rubinstein ()
Date: January 15, 2010 09:47AM

Hello all,

.NET framework = 3.5, MySQl .Net connector = the latest.

I'm running into a "Concurrency violation: the UpdateCommand affected 0 of the expected 1 records." exception when I try to use the Update method, here is the code:

the table :
CREATE TABLE IF NOT EXISTS `vcard` (
`vcard_idx` INT(9) NOT NULL AUTO_INCREMENT ,
`pincode` INT(4) UNSIGNED NULL DEFAULT NULL ,
`rfid` INT(6) NULL DEFAULT NULL ,
PRIMARY KEY (`vehicle_card_idx`) )
ENGINE = INNODB

the update SQL:
private const string UPDATE_SQL = "UPDATE vcard SET pincode = @pincode, rfid = @rfid WHERE vcard_idx = @idx";

here is how I load the update MySqlCommand: (da = DataAdapter)

da.UpdateCommand = new MySqlCommand();
da.UpdateCommand.CommandText = UPDATE_SQL;
da.UpdateCommand.Parameters.Add("@idx", MySqlDbType.Int16);
da.UpdateCommand.Parameters.Add("@rfid", MySqlDbType.Int16);
da.UpdateCommand.Parameters.Add("@pincode", MySqlDbType.Int32);

(also tried without giving a DBType)

at this point it is also important to add the fact that there was a query done to the database using
the same adapter, which, from the return results one of the rows is entered onto a form for update.

after the data was modified by user.
comes the code that creates the Exception:
(ds = the DataSet, table = the DataTable)
VCard vc = (VCard) entity; //this is a very basic object entity object with properties
DataRow row = table.Rows[CurrentRecord];
row.BeginEdit();
row["pincode"] = vc.Pincode;
row["rfid"] =vc.Rfid;
row["idx"] = vc.CardIdx;
row.EndEdit();
da.UpdateCommand.Connection = getConnection();
da.Update(dataSet, tableName); //<- the exception is thrown here
dataSet.AcceptChanges();
da.UpdateCommand.Connection.Clone();

and:

protected MySqlConnection getConnection()
{
return new MySqlConnection(connectionString);
}

the get was added because of a no connection to UpdateCommand exception.

just for the sake of argument I tryed a different approach with the same SQL
update and Parameter that works, yes, THIS WORKES!

VCard vc = (VCard) entity;
MySqlConnection conn = getConnection();
conn.Open();
MySqlCommand cmd = new MySqlCommand(UPDATE_SQL, conn);
MySqlParameter idx = new MySqlParameter();
idx.ParameterName = "@idx";
idx.MySqlDbType = MySqlDbType.Int16;
idx.Value = vc.CardIdx;
cmd.Parameters.Add(idx);

MySqlParameter pin = new MySqlParameter();
pin.ParameterName = "@pincode";
pin.MySqlDbType = MySqlDbType.Int16;
pin.Value = vc.Pincode;
cmd.Parameters.Add(pin);

MySqlParameter rfid = new MySqlParameter();
rfid.ParameterName = "@rfid";
rfid.MySqlDbType = MySqlDbType.Int32;
rfid.Value = vc.Rfid;
cmd.Parameters.Add(rfid);

cmd.ExecuteNonQuery();

conn.Close();

any idea?

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Subject Written By Posted
DataAdapter Concurrency violation Gal Rubinstein 01/15/2010 09:47AM


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