You can read about this Android App that I wrote for the Caringbah based school on this link:
https://ssapps.com.au/case-study-mobile-app-for-a-martial-arts-school
And here is a video of me explaining it:
Also, as mentioned previously, this was all coded in Microsoft SQL Server and Visual Basic ... in less than an afternoon (it attached to the existing SQL gym database)
Merry Christmas ... I'm aiming to write more in the New Year.