Three shops, three sales sheets
A bike company has three shops. Each shop keeps its own sales sheet. The owner wants one report for the whole company.
Where should all that data go so one report can use it?
Key words
| Word | What it means | Example |
|---|---|---|
| Data warehouse | one big store that collects cleaned data from many systems | sales_warehouse |
| Business intelligence | using data to help a firm decide | |
| Data mart | a small warehouse for one area of the firm | |
| Spreadsheet | data in rows and columns, made in a program | |
| Cell | one box in a spreadsheet, named by column and row | B2 |
| Worksheet | one page of cells inside a spreadsheet file |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can say what a data warehouse, a data mart and a spreadsheet each hold and why.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
A warehouse centralises data
A data warehouse collects data from many systems into one place. The data is cleaned and put in one shape first.
That is why a firm can ask one question across every shop. Warehouses support business intelligence: reports that help leaders decide.
Try it: one question, every shop
-- The warehouse holds all three shops in one table.
select shop, sum(units) as total_units
from sales_warehouse
group by shop
order by total_units desc;
-- Try it: change the last line to order by shop.A data mart serves one area
A data mart is a simple warehouse for one area, such as the Leeds shop or the finance team.
It holds only what that area needs. So it is smaller, quicker and easier to understand.
Try it: cut a mart
-- A mart is a slice of the warehouse for one shop.
select month, product, units
from sales_warehouse
where shop = 'Leeds';
-- Try it: change Leeds to York.Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.