Code Lab BetaBUILD. RUN. DISCOVER.
Code Lab is in development. New lessons and improvements are on the way. Progress can be deleted.
Loading…
Code Lab is in development. New lessons and improvements are on the way. Progress can be deleted.
Loading…
Code Lab is in development. New lessons and improvements are on the way. Progress can be deleted.
SQL / POSTGRESQL / Learn / LESSON 07
UPDATE or DELETE without WHERE affects every row in the table. That is powerful and dangerous. This task intentionally changes the whole table — in real work you almost always want WHERE.
Small example:
UPDATE items SET price = price + 1; -- every rowStarting 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 or DELETE without WHERE affects every row in the table. That is powerful and dangerous. This task intentionally changes the whole table — in real work you almost always want WHERE.
QUERY STANDBY
›