Question

This is probably easy to do but I have a table which list items by price and has a version number for each item, so there is duplicate items with the same itemID and item name but the different versions might have different prices. I wanted a simple sql statement to check which items prices have changed

itemid | item | price  |version | date
1         a      1.13    1        2011-12-01
2         b      5.13    1        2011-12-01
3         c      3.66    1        2011-12-01
4         a      1.03    2        2012-01-09
5         b      5.13    2        2012-01-09
6         c      3.33    2        2012-01-09  

There will be numerous versions so guess I need to some kind of comparison function but not sure where to start in SQL.

So the above example I would only want to fetch back item a and c as there price has changed from the previous version.

Answer 1

Try:

SELECT item, COUNT(DISTINCT price) prices
FROM yourTable
/* WHERE clause would go here */
GROUP BY item
HAVING COUNT(DISTINCT price) > 1

Optionally include:

WHERE version in (1,2)

– if you only want to compare the specific versions 1 and 2.