Group Multiple Rows Into One

creating a query to group identical rows into one and placing corresponding data in appropriate columns for a table named items, what I mean is that I have a table structured as below

Itemcode, Description, Period1, Period2, Period3
001--------Desc--------233,---------,------- <<ROW1
001--------Desc ------------ ,100,------------ <<ROW2
001--------Desc ------,--------,-------,300 <<ROW3

Row one contains a value in Period1
Row two contains a value in Period 2
Row three contains a value in Period 3

I need to create a query so that the end result would look like this;

Itemcode, Description, Period1, Period2, Period3
001 --------Desc -------233 ----100 ---300

creating an sql query to get the above result?