Timestamp when querying the database, how to implement?

Question

Oracle

Table with ntimestamp#. How can I make each request start from the moment the previous one was launched?

select column1 
from table1
where table1.ntimestamp > ?

Answer 1

Store the start time in a separate table.

Answer 2

If by "each request started from the moment the previous one was launched" it is understood that data is needed for a specific period of time, i.e. not taking into account changes in the table since the specified time, then you can use the retrospective memory area ( https://docs.oracle.com/cd/B14117_01/appdev.101/b1... Example:
SELECT * FROM employee AS OF TIMESTAMP
TO_TIMESTAMP(' 2003-04-04 09:30:00', 'YYYY-MM-DD HH:MI:SS')
WHERE name = 'JOHN';
i.e. query to the table -SELECT * FROM employee Before executing the first query save the label time and insert in this way in all queries.If the difference in fractions of seconds is acceptable, then you can create cursors in a row to all the tables of interest, i.e.
pass the label scn - AS OF TIMESTAMP TO_TIMESTAMP('2003-04-04 09:30:00', 'YYYY-MM-DD HH:MI:SS')
condition - WHERE name = 'JOHN';
declare
x1 refcursor;
x2 refcursor;
...
begin
open x1 for select * from t1;
open x2 for select * from t2;
....
end;
Then, when running, the cursors will display data with a difference of fractions of a second.