Counter

I'm not very familiar with sql. I'm designing a database into oracle db. The problem is how to create a table with one column which includes a kind of rowId. That number should be running and when any record is deleted that number should not vanish.
So if I had numbers 1,2,3,4,5,6 and I delete a record 3, record 4 should become number 3 etc. If I add a record it is allowed to become number 7. Should this be done with some kind of indexing or with some counter? Or is there some kind of internal variable in the database? I'm using sqlplus and Oracle database.
What kind of statement should I make?

Any help would be appreciated !

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         #  Harri M Pihlajavesi         #         

         #  harrimp_at_evitech.fi          #


         #  harrimp_at_cism.bus.utexas.edu #


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