用法错误
OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);
// Create the Insert, Update and Delete commands.
da.InsertCommand = new OleDbCommand(
"INSERT INTO Customers (CustomerID, CompanyName) " +
"VALUES (?, ?)");
da.UpdateCommand = new OleDbCommand(
"UPDATE Customers SET CustomerID = ?, CompanyName = ? " +
"WHERE CustomerID = ?");
da.DeleteCommand = new OleDbCommand(
"DELETE FROM Customers WHERE CustomerID = ?");
