with jdata as ( 
    select treat('{"practitionerId":12345,"gender":"F"}' as json) as jrow 
    from dual 
    ) 
select j.jrow.practitionerId 
from jdata j

declare 
    p_input_json varchar2(32767) := '{"practitionerId":12345,"gender":"F"}'; 
    p_practitioner int; 
     
begin 
    with jdata as ( 
        select treat(p_input_json as json) as jrow 
        from dual 
        ) 
    select j.jrow.practitionerId 
        into p_practitioner 
    from jdata j; 
end;