MySQL UPDATE Query
UPDATE changes the data of existing rows.
UPDATE students
SET marks = 70
WHERE name = 'Vikram';
MySQL says
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
SELECT name, marks FROM students WHERE name = 'Vikram';
Result
| name | marks |
|---|---|
| Vikram | 70 |
Note:
Never forget WHERE. UPDATE students SET marks = 0; changes every row of the table. Test your WHERE with a SELECT first.
Update many columns
UPDATE students
SET city = 'Pune', marks = 72
WHERE id = 5;Calculate the new value
UPDATE students
SET marks = marks + 5
WHERE city = 'Mumbai';
MySQL says
Query OK, 2 rows affected (0.01 sec)
Rows matched: 2 Changed: 2 Warnings: 0
Both Mumbai students got 5 more marks.
Put the data back
The next chapters use the original data, so restore it with these commands.
UPDATE students SET city = 'Delhi', marks = 65 WHERE id = 5;
UPDATE students SET marks = marks - 5 WHERE city = 'Mumbai';You can also read how this is done from Python.
Summary
UPDATE table SET column = value WHERE condition;- Without
WHEREall rows change. - Next: DELETE.
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