ORA-00097: use of Oracle SQL feature not in SQL92 Full Level

Error Explanation:
SQL> conn arju/arju
WARNING:
Use of Oracle SQL feature not in SQL92 Full Level.
Connected.

Cause of The Error:
You tried to use an Oracle SQL feature that is not compliant with the SQL92 standard.

Description:

Setting SQL*Plus environment variable Flagger checks to make sure that SQL statements conform to the ANSI/ISO SQL92 standard.
If any non-standard constructs are found, the Oracle Database Server flags them as errors and displays the violating syntax.When FIPS flagging is enabled, SQL*Plus displays a warning for the CONNECT, DISCONNECT, and ALTER SESSION SET FLAGGER commands, even if they are successful.

Solution:
Do not use the feature or use the ALTER SESSION SET FLAGGER command to set the appropriate level of SQL92 compliance.

SQL> ALTER SESSION SET flagger=OFF;
ERROR:
ORA-00097: use of Oracle SQL feature not in SQL92 Full Level

Session altered.

SQL> conn arju/arju
Connected.