>>The database is in the server, while MySQL engine is installed in all PCs (server and clients).
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>Sorry, without further explanation this makes no sense at all. Benefit of MySQL / MariaDB / Postgres / Oracle / DB2 / SQL server is to keep all data on one beefy server. Keeping a local data copy on each client and replicating across all machines feels wasteful at least and an accident waiting to happen

Ironically, I recall seeing apps architected this way because they started life as file-server databases such as VFP or Access. The makers then decided to get some benefits of RDBMSs but put zero effort into creating actual client-server applications. They end up with a local DB install so they can do local data munging like VFP, and the local DB talks to the server DB (if present; this architecture allows for standalone use as well). Often there is zero smarts in how this is used. For example, if a workstation is asked to find a customer by name, the local DB pulls the whole customer table across the LAN from the server DB, and then filters it locally to get the result.