Hijrah Date in Oracle Database

Some Arabic countries use Hijrah calendar specially in Saudi Arabia.
So today I will post about Hijrah Date and how to convert between different calendars.

The main notes in this post
1-NLS Calendars in Oracle Database
2-Convert Georgian calendar to Hijrah calendar
3-Convert Hijrah Calendar to Georgian
4-Fix deviations between calendars
5-How to create lexical file for the deviation

Get Oracle Home & Oracle SID from PLSQL

The below script gets Oracle Home and Oracle SID from PL/SQL

 DECLARE  
   LC$ORACLE_HOME  VARCHAR2 (2000);  
   LC$ORACLE_SID  VARCHAR2 (256);  
 BEGIN  
   DBMS_SYSTEM.GET_ENV ('ORACLE_HOME', LC$ORACLE_HOME);  
   DBMS_SYSTEM.GET_ENV ('ORACLE_SID', LC$ORACLE_SID);  
   
   -- Oracle Home  
   DBMS_OUTPUT.PUT_LINE ('ORACLE_HOME = ' || LC$ORACLE_HOME);  
   
   -- Oracle SID  
   DBMS_OUTPUT.PUT_LINE ('ORACLE_HOME = ' || LC$ORACLE_SID);  
 END;  

Thanks