ReportSQLQuerry_SumingQtyShipped

STOCK_ITEMS

NAME                   type
------------------------------------------------------------------------
STOCK_NUMBER            VARCHAR2(20)
.......


SHIPMENT

Name                                      Null?    Type
----------------------------------------- -------- ----------------------------
SHIPMENT_ID                               NOT NULL NUMBER(10)
ORDER_NO                                           NUMBER(10)
SHIPMENT_DATE                                      DATE
SHIP_FROM_ORG                                      VARCHAR2(8)
SHIP_TO_ORG                                        VARCHAR2(8)
...


SHIPPED_ITEMS

Name                                      Null?    Type
----------------------------------------- -------- ----------------------------
SHIPMENT_ID                               NOT NULL NUMBER(10)
STOCK_NUMBER                              NOT NULL VARCHAR2(20)
ITEM_NUMBER                               NOT NULL NUMBER(2)
QUANTITY_SHIPPED                                   NUMBER(8)
SHIPCODE                                           VARCHAR2(1)
created_date                                       DATE


I have the above 3 tables.

I need to report on 1 month, 6 month, 1 year, 2 year, 5 year and 10 year usage for each stock item. This is the total quantity shipped in each period. How would you write the SQL for that. Would you use subquery for each calculation and include that in main query like this or that would be slow and it better to do the whole clculations in one scan using CASE.

select stock_number, (query1) 1_mon, (query2) 6_mon, (query3) 1_yr, (query 4) 2_yr, (query5) 5_yr from stock_item;

query1 = select sum(quantity_shipped) from shipped_item a WHERE created date between trunc(sysdate) and trunc(sysdate-30);