Use php to update a row value by -1

PHP
1

Can anyone tell me how I can subtract 1 from a value in mysql and update the value in the table to show the new value.

The current value is 120.
I want to run a php file which will then update the value in MYSQL to show 119.

Any suggestions?

Thanks for any help in advance.

2

UPDATE tablename
SET fieldname = fieldname - 1
WHERE …

3

Thanks guido2004!