Command to get SGA Size Advice and Usage !

The Following Query helps to find out the SGA Size Advice :

select sga_size, sga_size_factor, estd_db_time, estd_db_time_factor, estd_physical_reads from v$sga_target_advice order by sga_size_factor;


SGA usage :
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select sum(value)/1024/1024 "Megabytes" from v$sga;

select component, current_size from v$sga_dynamic_components;