set serveroutput on;
set feedback off;
DECLARE
	block_buffers	number(20);
	block_size	number(20);
	large_pool	number(20);
	shared_pool	number(20);
	java_pool	number(20);
	log_buffer	number(20);
	sga_size	number(20);
	dbms_version	number(1);


BEGIN
	SELECT  to_number(value) INTO block_buffers from v$parameter
	where name ='db_block_buffers';
	
	SELECT  to_number(value) INTO block_size from v$parameter 
	where name = 'db_block_size';

		SELECT  to_number(value) INTO shared_pool from v$parameter
		where name like 'shared_pool_size'; 
	BEGIN
		SELECT  to_number(value) INTO large_pool from v$parameter
		where name like 'large_pool_size';
	EXCEPTION
       		WHEN NO_DATA_FOUND  THEN
      		large_pool := 0; 
	END;

	BEGIN
		SELECT  to_number(substr(value,1,5)) INTO java_pool from v$parameter
		where name like 'java_pool_size';
	EXCEPTION
		WHEN NO_DATA_FOUND  THEN
		java_pool := 0;
	END;

	SELECT  to_number(value) INTO log_buffer from v$parameter
	where name like 'log_buffer';
	
	SELECT  substr(value$,1,3) INTO dbms_version from sys.props$ where name ='NLS_RDBMS_VERSION';

	IF dbms_version = 8.1 THEN

		sga_size := (((block_buffers*block_size) + large_pool + shared_pool + java_pool +  log_buffer + 1000)/1000/1000) + 1;

	ELSIF dbms_version = 8.0 THEN

		sga_size := (((block_buffers*block_size) + large_pool + shared_pool + log_buffer + 1000)/1000/1000) + 1;

	ELSIF dbms_version = 7.3 THEN

		sga_size := (((block_buffers*block_size) +shared_pool + log_buffer + 1000)/1000/1000)/.9;

	END IF;

	dbms_output.put_line('=============================');
	dbms_output.put_line('SGA size :'||sga_size||' MB');
	dbms_output.put_line('=============================');

END;
/