【DB笔试面试495】Oracle中哪个包可以获取环境变量的值？

SYS@LHRDB1> VAR ENVOUT VARCHAR2(200);
SYS@LHRDB1> SET SERVEROUTPUT ON
SYS@LHRDB1> EXEC DBMS_SYSTEM.GET_ENV('ORACLE_HOME',:ENVOUT);
PL/SQL PROCEDURE SUCCESSFULLY COMPLETED.
SYS@LHRDB1> PRINT ENVOUT
ENVOUT
-------------------------------------------------------------------
/oracle/app/oracle/product/11.2.0/db
SYS@LHRDB1> SET SERVEROUTPUT ON
SYS@LHRDB1> DECLARE
  2  RETVAL VARCHAR2(4000);
  3  BEGIN
  4  SYS.DBMS_SYSTEM.GET_ENV('ORACLE_SID', RETVAL);
  5  DBMS_OUTPUT.PUT_LINE(RETVAL);
  6  END;
  7  /
LHRDB1
PL/SQL procedure successfully completed.
SYS@LHRDB1> DECLARE
  2  RETVAL VARCHAR2(100);
  3  BEGIN
  4  SYS.DBMS_SYSTEM.GET_ENV('ORACLE_HOME', RETVAL);
  5  DBMS_OUTPUT.PUT_LINE(RETVAL);
  6  END;
  7  / 
/oracle/app/oracle/product/11.2.0/db
PL/SQL procedure successfully completed.