Comments by Pankajk.Singh (Top 1 by date)

string QryForSupp = " Select col1 as PkID001 from ABC ";

SqlDataAdapter SqlDAforSupp = new SqlDataAdapter(QryForSupp, Con);
DataSet dsStockMaster = new DataSet();
SqlDAforSupp.Fill(dsStockMaster);
DataTable OrgStockMaster = dsStockMaster.Tables[0];

OrgStockMaster.PrimaryKey = new DataColumn[] { OrgStockMaster.Columns["PkID001"] };


if (oraConn.State != System.Data.ConnectionState.Open)
{
oraConn.Open();
}

string checkQry = "SELECT col1 as PkID001 FROM AAA ";

DataSet StkFrmOracle = new DataSet();
OleDbCommand cmdStockMast = new OleDbCommand();
cmdStockMast.CommandText = checkQry;
cmdStockMast.CommandType = CommandType.Text;
cmdStockMast.Connection = oraConn;
OleDbDataAdapter odaForStock = new OleDbDataAdapter(cmdStockMast);
odaForStock.Fill(StkFrmOracle);

DataTable dtOracleStock = StkFrmOracle.Tables[0];

dtOracleStock.PrimaryKey = new DataColumn[] { dtOracleStock.Columns["PkID001"] };

dsStockMaster.Merge(StkFrmOracle); //This line is throwing Exception.
DataSet dsDiff = dsStockMaster.GetChanges();
My Oracle Column is of Data Type "varchar2", while SQL Column is "Varchar".
I think this is why I'm getting exception.