Question

I have a table in sql having two fields ‘JOB_NUMBER’ ‘SRno’, the relation between the two is such that each job number has many SRNO starting from 1,2,3 and so on,every new Job number has to have a SR no starting form 1,

so my ideal table should some what look like this:

JOB_NUMBER    SRno
   1            1
   1            2 
   1            3
   2            1
   2            2
   3            1 and so on.......

What I want to do is to achive this indexing in sql itself ,can I do this ,is so how?

Answer 1

If there is another column on the table that is something like a timestamp (e.g. time submitted), then you can do something like:

select job_number, 
   row_number() over (partition by job_number order by time_submitted asc) as SRno
from tbl

You could make that into a view and you’re good to go. Keep in mind that this will be sensitive to data modifications (i.e. if someone inserts a row between two other rows, the rows after the inserted one will be “renumbered”). Also keep in mind that this won’t store the SRno on the table; it has to be calculated dynamically.