Sampling a Table
Getting a few random rows from as Oracle Database table can be done in many different ways.
This will just select the first ten rows Oracle comes across in the table:
select * from iso_country where rownum<=10
They are likely to all be inserted at a similar time and therefore all similar. If you need a cross section:
select * from iso_country sample (10) -- percentage of rows to display
The percentage of rows is not precise, there are 249 rows in the sample iso_country table, but the 10% sample count has given a range from 15 - 31 rows:
select count(*) from iso_country sample (10) -- percentage of rows to display
Additional conditions can be added to a sampling query, but they appear to be applied after the original sample has been taken, so there is no guarantee that the query will show any rows:
select * from iso_country sample (10) where code like 'A%'
There are many countries in the table that start with A, so the sample must be taken before the criterion is applied.