In reply to piyushpatel123:
Using the Default sequence Approach the sequence is started automatically. You don’t have to perform get on the uvm_config_db.
In contrast to the OVM you have to set the default_sequence on the run_phase of the sequence under consideration like this:
class my_test extends uvm_test;
function void build_phase(uvm_phase phase);
uvm_config_db#(uvm_object_wrapper)::set(null, "/.*sequencer.run_phase/",
"default_sequence", my_sequence::get_type() );
....
endfunction