Tips

Short reminders on GitLab, Git, SQL, Docker, QA and front design, a few examples each, to be completed together.

Click a tab to change topic. In Front design, Let it snow covers the page with snow until clicked again, and a click on the wood leaves a bullet hole; nothing calls a server.

Tips

Short reminders, one tab per topic. To be completed together.

Open a merge request from the terminal
Push the branch, then create the MR with a title and a label.
```
glab mr create --fill --label "To Review"
```
Read a failed job without the browser
The last pipeline of the branch, then the log of a job.
```
glab ci status
glab ci trace unit-tests
```
Suggest a fix in a review
A suggestion block in a diff comment: the author applies it in one click.
```
```suggestion:-0+0
assert response.status_code == 404
```
```
Lint a pipeline before pushing it
Catches a broken include or a wrong key without a pipeline run.
```
glab ci lint .gitlab-ci.yml
```

Branch fresh from main
Fetch first, then branch from the remote main, not from a stale local one.
```
git fetch origin
git switch -c feat/my-change origin/main
```
Conventional commits
The type says what the change is, the release tool reads it.
```
feat: show the stock of open bugs
fix: count a rejected bug as closed
```
Rewrite the last commit
Forgot a file: stage it and amend, before pushing.
```
git add src/forgotten.py
git commit --amend --no-edit
```
Find the commit that broke a test
Git bisects the history, running the test at each step.
```
git bisect start HEAD v1.4.0
git bisect run pytest tests/unit -q
```

Count before you look
A COUNT(*) tells whether the rows you expect are there at all.
```
SELECT status, COUNT(*) FROM orders GROUP BY status;
```

Rows without a match

A LEFT JOIN and an IS NULL: the orders nobody invoiced.

SELECT o.id FROM orders o
LEFT JOIN invoices i ON i.order_id = o.id
WHERE i.id IS NULL;

Try a write, then undo it

In a transaction, check the result, then roll back.

START TRANSACTION;
UPDATE stock_levels SET quantity = 0 WHERE id = 3;
SELECT * FROM stock_levels WHERE id = 3;
ROLLBACK;

Which tables does a query read?
EXPLAIN lists them, with the index used for each.
```
EXPLAIN SELECT * FROM customers WHERE username = 'ada';
```

Follow one service's logs
Only the last lines, then live.
```
docker compose logs -f --tail 50 api
```
Open a shell in a container
Look at what the service really sees: files, variables, network.
```
docker compose exec api sh
env | grep DB_
```
Rebuild one service only
Faster than restarting the whole stack.
```
docker compose up -d --build console
```
Free the disk
Stopped containers, dangling images and the build cache.
```
docker system df
docker system prune
```

Search first, then read
Look for an existing helper or test before writing a new one: reuse before writing.
Never weaken a CI gate
A red gate is fixed, not silenced: no lowered threshold, no skipped job to get a merge.
Official tooling, local identical to CI
Run the same hooks and the same commands as the pipeline before pushing.
```
mise run hooks:run
mise run test
```
No magic value
A business value gets a named constant that says what it means.
```
STALE_DAYS = 28  # not: if age > 28
```
No masking fallback
A missing value fails loudly; a silent default hides the bug the test should have caught.
A test writes its own data
Its own account, its own plus address; restore what it changed so the next run starts clean.

A canvas over the page, flakes drawn in a requestAnimationFrame loop; click again to stop.

Click the wood to shoot: the hole lands where the pointer is.

The same bullet hole as a static image on a transparent background (the checkerboard shows through): download the SVG.

An entry card with its orange Beta ribbon across the corner of the icon.