Opdateringssekvens for specifik tilstand - Oracle

Hvorfor ikke bare bruge substr() ?

select t.*, to_number(substr(element_id, 3, 2)) as my_seq
from t;

En anden tilgang er at bruge dense_rank() :

select t.*,
       dense_rank() over (partition by u_a_id order by substr(element_id, 1, 4)) as my_seq
from t;

Du kan bruge merge hvis du rent faktisk vil opdatere dataene:

merge into t using
      (select t.*,
              dense_rank() over (partition by u_a_id order by substr(element_id, 1, 4)) as new_my_seq
       from t
      ) s
      on s.u_a_id = t.u_a_id and s.element_id = st.element_id
when matched then update
    set t.my_seq = s.new_my_seq;