In AGPLv3 and GPLv3, clause 5c says:
You may convey a work based on the Program, or the modifications to produce it from the Program [only if you] license the entire work, as a whole, under this License
but then, 0 Definitions:
To "modify" a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a "modified version" of the earlier work or a work "based on" the earlier work.
Does it mean that I have to modify the source to actually make my code fall under (A)GPL? Or just relying on (A)GPL software (let's say a database) makes my software automatically 'adapt' the (A)GPL software?
In the license there is nothing about 'derivative work'.