Updating Rows

If we can SELECT rows, and INSERT data into rows, we can most certainly UPDATE them as well.

UPDATE works similarly to INSERT, and needs a WHERE clause to specify which rows should be updated:

UPDATE mytable
SET column = value_or_expression
    other_column = value_or_expression
    ...
WHERE condition;

Obviously, like INSERT, the values or expressions returned should match the data type of the expected column/property.

A helpful tip is to always try a SELECT statement out first to make sure you are grabbing all the rows you think you want before you make any changes.

Deleting Rows

Deleting rows is actually quite simple;

DELETE FROM mytable
WHERE condition;

Just make to sure to use this statement with caution; if you leave out the WHERE clause, all rows will be deleted.

Same tips as updating; try a SELECT statement to grab all rows you want to make sure it works before deleting.

Next: Lesson 16