select  id,
         number_sequ,
         startvalue
         lead(startvalue,1,0) over (partition by id order by number_sequ) AS End_value
 from mytable

id             number_sequ   startvalue       End_value
         ----            -----       ----------       -----------
          AAA             1             30              20
          AAA             2             20              10
          AAA             4             10              15
          AAA             5             15              0
          BBB             1             12              23
          BBB             3             23              34
          BBB             4             34              0

id         number_sequ   startvalue       End_value
     ----         -----       ----------       -----------
       AAA          3
       BBB          2

INSERT INTO mytable (id,number_sequ,startvalue)
      select id ,number_sequ ,'0'  from mytable where (some condition to specify missing data)