Export data in columns and rows (MySQL+PHP) into an Excelspreadsheet

I want to export data from a matrix (e.g. 15 columns/600 rows from different tables) into an Excel-spreadsheet for further analysis and report. The method should be so easy (userfriendly) that any user can export the data.

Can anyone tell me where to find a tutorial or an extension?

It would be perfect if it also worked visaversa: if I could fill DB-tablecells via an Excelspreadsheet.

Thanks in advance!!