Oracle database is set to read-only and read-write

Query the current state of the database (assumed to be read-write) and change it to read-only.

sqlplus /nologconnect / as sysdba -- login as DBA --select open_mode from v$database; -- read-only or writable when querying the current state of the database --shutdown immediate --warnning: make sure there is no real process to execute before executing --startup mount --load database--alter database open read only; --change the database to read-only state--

Changes the database from read-only to writable.

sqlplus / as sysdbaselect open_mode from v$database;shutdown immediatestartup open read write;