Checked, but is it saved safely?
Zara checks a sign-up list. She finds three bad rows and fixes them. Then she saves the file on a shared drive that anyone can open.
The data is now clean but exposed. The job is not just to check. It is also to judge the sources and to save the result safely.
Key words
| Word | What it means | Example |
|---|---|---|
| Validation | A check that data is sensible and in the right shape. | Age from 11 to 18 |
| Verification | A check that data matches the original. | Compare with the paper form |
| Personal data | Data that can identify a living person. | A name with an age |
| Dataset | A collection of related data kept together. | The sign-up list |
| Reliable | A source you can depend on to give the same, correct data each time. | An official register |
| Valid | Right for the purpose it is used for. | Age data for an age question |
| Trusted source | A source with a good record, which you can name and point to. | A national statistics body |
| Cite | To name where your data came from. | Source: school register, March |
| Lookup table | A list of allowed values to check against. | The list of rooms |
| Access control | Deciding who may open or change a file. | Only the club team |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can apply checks to a dataset, judge how reliable its sources are, and save the result safely.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Judging a source
| Question | Good sign | Bad sign |
|---|---|---|
| Who made it? | A named body with a record | Nobody knows |
| How old is it? | Recent, with a date | No date |
| Can I check it? | A second source agrees | Nothing to compare |
| Does it fit my need? | Same group and place | A different group |
The cells students fill in are left blank in this preview.
Try it: flag the failing rows
select id, name,
case
when age < 11 or age > 18 then 'age out of range'
when room not in (select room from rooms) then 'room not allowed'
else 'ok'
end as result
from signups
order by id;
-- Try it: change 18 to 40 and press Run.Saving the result securely
Save the checked dataset in a place with access control. Give it a clear name and a date. Keep the original as well.
If it holds personal data, limit who can open it and remove what is not needed. Write down the source, so others can cite it.