Is it possible to synchronize a Mysql database that is in the cloud and display its data in an ArcGIS Online web layer?
@DambéSANWOGOU you'd need to serve the data via Enterprise as an RDBMs, and MySQL isn't supported:
You're better off looking at PostgreSQL.
Otherwise you could look to write a python script that pulls the data down to a local geodatabase, and then overwrites/appends/deletes the deltas in your AGOL service?