I recommend Power Bi Desktop. It is a free application to download and free to use. It has a very robust community users helping others and has a trove of open source visuals to use to build reports. It fulfills all of your requirements (except the PHP one):
retrieve data stored in a database or similar
Power Bi Desktop can pull from a wide variety of data sources: databases (SQL, Oracle, etc), files (excel, text, csv, etc) and online feeds (rest, rss, html, odata, etc) and can also pull from SharePoint or Web Pages. Check the long list at the bottom of link above
work with the data
Power Bi desktop lets you define how the data will be handled when you pull it in. How to handle nulls? split values into new rows or columns based on delimiters, embed new logic or processing is all possible.
present it in a understandable manner
There are many visuals available out of the box to present your data to the users: dials, gauges, bar charts, cards, pie charts, tables, grids, lines, maps, etc.
Also as an added bonus, if your users are viewing the report with a computer or online, they can slice the data (interact with the report) and the visuals change according to the interaction. This is a nice feature that most of the older BI tools do not have. On the other hand, you can do a screen grab of a report to save a static view of the report as an image to use in a web page, presentation or printout.
If your visual is not yet developed, you can create your own and share it with the community. Or fork one of the existing visual code bases and add the feature you need to an existing visual.
All of this is free and Microsoft has been putting out monthly releases with new features for the past year. Microsoft is currently committed to make this a solid product used by people around the world.
I have been using it for the past 6 months and I can attest it is very intuitive and useful and once you get over the initial learning curve. You will be able to create impressive reports that are interactive and get data refreshed from your data sources regularly.
Here is a ton of free learning resources online:
- Download and try the sample reports online and inside the help menu.
- Join Robust user community and to post questions and get help
- Check out Guy in a Cube you tube series. Two power users giving tips for people to get started
- Create your own visual.
I'm a developer and have been working with Microsoft tools and platforms for the last 10 years and have not been happy with much of it. However, Power Bi is one of the new products they are getting right! Free to use, monthly upgrades, vibrant user community and helpful support. Along with VS Code, these offerings are encouraging to see coming from Microsoft and makes me optimistic about their future.