Data goes stale, like food
Harbour Sports (a made-up shop) has kept its customer list for three years. People moved house. Some joined twice. One member of staff left but can still sign in.
Nobody did anything wrong in a single day. The data just went stale. A plan for looking after it stops that.
By the end of this lesson
Note
I can plan data maintenance tasks on a schedule and outline a user manual for a data system.
Key words
| Word | What it means |
|---|---|
| Data maintenance | regular jobs that keep data correct and safe |
| Schedule | a plan that says what is done, by whom and how often |
| Backup | a spare copy of data kept in case of loss |
| Archive | to move old data to separate storage |
| User manual | a guide that shows people how to use a system |
The cells students fill in are left blank in this preview.
Starter: what you already know
Have a go
Starter: what you already know
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Maintenance keeps data correct and safe
Data maintenance means regular jobs that keep data correct, safe and useful. Without them, errors collect, the system slows down and people stop trusting the numbers.
Six jobs matter most. Each one has a reason and a rhythm: some are done daily, some monthly, some once a year.
Six maintenance jobs
| Job | What it does | How often (an example) |
|---|---|---|
| Backup | Saves a spare copy | Every night |
| Integrity check | Looks for duplicates and broken links | Every week |
| Update records | Corrects out of date details | When a change is reported |
| Archive | Moves old records out of daily use | Every year |
| Access review | Removes people who should not sign in | Every month |
| Test a restore | Proves a backup can be used | Every three months |
The cells students fill in are left blank in this preview.
Try it: archive old sales
-- Copy January sales to an archive table, then remove them from the live table.
CREATE TABLE sales_archive AS SELECT * FROM sales WHERE 0;
INSERT INTO sales_archive SELECT * FROM sales WHERE sale_month < '2026-02';
DELETE FROM sales WHERE sale_month < '2026-02';
-- Integrity check: live plus archive must still equal 12.
SELECT (SELECT COUNT(*) FROM sales) AS live,
(SELECT COUNT(*) FROM sales_archive) AS archived,
(SELECT COUNT(*) FROM sales) + (SELECT COUNT(*) FROM sales_archive) AS together;
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.