When designing a custom report, you can also define a formula like "MarginPct."  It has a value taken from a complex SQL column definition using numeric fields to compute the margin percent.

Normally, you will test the formula in the PSQL Control Center to make sure it works. For example:

SELECT CPPROMIT_ITEM_NO_ALT, ITEM_DESC1, CPPROMIT_BATCH_ALT, CPPROMBA_DESC, CPPROMBA_PRICE_APPLY, CPPROMBA_DISC_APPLY, CPPROMIT_START_DATE, CPPROMIT_END_DATE, CPPROMIT_PROJ_QTY, CPPROMIT_TTL_QTY, CPPROMIT_TTL_AMT, Case When cppromit_price = 0 Then 0.00 when cppromit_ttl_qty = 0 Then 0.00 Else (((cppromit_price - (cppromit_ttl_cost / cppromit_ttl_qty)) / cppromit_price)) * 100 END as MarginPct, CPPROMIT_PRICE FROM CPPROMIT left join cppromba on cppromba.cppromba_batch = cppromit_batch_alt left join imitmfil on imitmfil.item_no = cppromit_item_no_alt         ORDER BY CPPROMIT.CPPROMIT_ITEM_NO_ALT ASC       , CPPROMIT.CPPROMIT_BATCH_ALT ASC

The highlighted area is the formula being tested.

Defining the formula simply as  

(((cppromit_price - (cppromit_ttl_cost / cppromit_ttl_qty)) / cppromit_price)) * 100 

 will return a divide by zero error if the value of cppromit-price or cppromit_ttl_qty is zero. Using a case statement will resolve this error.

Case 

When cppromit_price = 0 Then 0.00 

When cppromit_ttl_qty = 0 Then 0.00 

Else (((cppromit_price - (cppromit_ttl_cost / cppromit_ttl_qty)) / cppromit_price)) * 100 

END 

Complex calculations can also be made using Telerik functions in the SQL Designer Template. In the example below, a simple aggregate function could not provide the value desired -- namely computing a value based on other aggregate values-- so a Telerik function was used.