how do i use update in a select query

[Razvan Licaret]

Hi everyone!
I'm looking for some help on how do I update a field in my query to a predifined value!
I have only managed to come as far as to create the SELECT query:

SELECT `mzm8e_jomcl_adverts`.`id` , `mzm8e_jomcl_extrafields_values`.`advertid`
FROM mzm8e_jomcl_adverts, mzm8e_jomcl_extrafields_values WHERE ((`mzm8e_jomcl_adverts`.`id`) = (`mzm8e_jomcl_extrafields_values`.`advertid`)) AND (`mzm8e_jomcl_adverts`.`userid`) =5560 AND (`mzm8e_jomcl_extrafields_values`.`fieldid`) = 5

The above query, correctly displays all the entries in which I need to update the field.
Currently, the value of fieldid 5 is "1" and I need to change that value to "2".
Any help would be highly appreciated!

Many thanks in advance!