At this moment, mysql database name no more then 16 chars with format AAA_BBB (AAA = client name and no more than 12 chars; BBB = additional chars; no more than 3 chars). Database username is the same same as database name (if dataname is tester_wp and username is tester_wp too).
The fact related to mysql naming:
1. database name possible UNTIL 64 chars
2. database username limiting to 16 chars
Propose for mysql database name and username:
1. Database name possible until 64 chars ( lowercase alphanumeric and '_') with format CCC_BBB (CCC = 4 chars for random lowercase alphanumeric; example: a1sd; BBB = lowercase alphanumeric; example: wordpress or wp123)
2. Database username as the same as client name -> all databases under 'tester' client always using 'tester' database username.