How does spring security do login authentication in the case of federated primary keys?

for example, it takes two fields to uniquely determine the login person, but the verification method loadUserByUsername has only one parameter of userName, so it is impossible to pass two parameters. How can login verification be realized?

Feb.26,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-34859f1-1e50e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-34859f1-1e50e.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?