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Code Lab is in development. New lessons and improvements are on the way. Progress can be deleted.
SQL / POSTGRESQL / Learn / LESSON 04
UPDATE changes existing rows. WHERE limits which rows change. Without a precise WHERE you risk changing too many. Grading checks the whole table after the change.
Small example:
UPDATE items SET qty = 99 WHERE id = 1;Starting tables for this task. Grading checks final state on other datasets too.
| id | name | category | qty | price |
|---|---|---|---|---|
| 1 | Pen | tools | 10 | 1.5 |
| 2 | Notebook | books | 5 | 3 |
| 3 | Mug | home | 2 | 8 |
| 4 | Sticker | NULL | 0 | 0.5 |
| 5 | Lamp | home | 1 | 25 |
| 6 | Book Atlas | books | 3 | 12 |
Expected verify columns: id, name, category, qty, price · row order is checked
Expected final state (displayed data):
Loading…UPDATE changes existing rows. WHERE limits which rows change. Without a precise WHERE you risk changing too many. Grading checks the whole table after the change.
QUERY STANDBY
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