create table section (
   sectionId    int
,  sectionName  varchar(32)
,  dateCreated  date
-- maybe some other fields that describe the section
-- status
)

create table inventoryItem (
   itemId            int
,  itemName          varchar(32)
,  sectionId         int
,  description       varchar(255)
,  photoLocation     varchar(255)
,  dateCreated       date
,  dateLastModified  date
,  status            int
,  price             numeric
,  salePrice         numeric NULL
)

##</code><code>##

create table itemPrice (
    itemId      int
,   price       numeric
,   type        int         -- 0 for normal, 1 for sale
,   validFrom   date        NULL
,   validTo     date        NULL
)

##</code><code>##

select s.sectionName
     , i.itemId
     , i.itemName
     -- other inventoryItem columns as needed
     , p1.price
     , "sale_price" = p2.price
  from section s left join inventoryItem i 
        on s.sectionId = i.sectionId 
    left join itemPrice p1 
        on i.itemId = p1.itemId and p1.type = 0 
    left outer join itemPrice p2 
        on p1.itemId = p2.itemId and p2.type = 1 
       and p2.fromDate < getdate() and p2.toDate > getdate()

##</code><code>##

            itemId             price                sale_price
 ---------- ------- ---------- -------------------- --------------------
 section 1        1 item 1                24.990000                 NULL
 section 1        2 item 2                19.990000            14.990000