How does the SAP user gets authenticated to oracle SAP database?

 For the database, the SAP system is a single user, SAPR3 / SAP<SAPSID>, whose password is stored in the table SAPUSER. Therefore, to access the database, the SAP System uses a mechanism called the OPS$ mechanism, which works as follows:

When the system accesses the database, it first logs on to the database as the user OPS$<operating_system_user>, for example, OPS$<SAPSID>adm.

(The OPS$ user that corresponds to the operating system user must be defined in the database and identified as externally.

It retrieves the password for SAPR3 from the SAPUSER table.

It logs on to the database as the user SAPR3 or /SAPR3DB.

OPS$ORACLE                         10-JAN-21

OPS$ORA<SID>                     10-JAN-21

OPS$<SID>ADM                     10-JAN-21