Hi Guys:

This is a general SQL question, not specifically Ingress-related. But I
know there are some experts on this list!

I have a table which has rows like:
Currency_code
Start_date
End_date
Other_data

For any given currency, I should have rows like:

CURR 20070101 20070315
CURR 20070315 20070620
CURR .....
CURR 20070723 NULL

That is, the end date of the row should match the start date of the next
row, if we view the rows in START_DATE sequence.

I need to validate that this is in fact so. I.e that there are no gaps
in coverage.
It is a (one-off)diagnostic task only - there is no need for the
solution to be elegant, it just has to work: nevertheless, elegance is a
'good thing'.

It is a given that the latest row will always have a null end_date, and
start_date will always be non-null.

My current approach is in three parts:

1. Verify that end_date> start_date for all rows, counting null as
2039-12-31 via a coalesce.
2. Create a temporary table of 'min(start_date)' for all currencies.
3. Do an exception join of all start dates against all end_dates, where
the start_date is not equal to the corresponding min(start_date) from
the temporary table, and end_date is not null.
i.e validate that the starts and ends match, excluding the first start
date and latest end_date.

This seems to work ok, but can anyone come up with a better all-SQL
solution?

Cheers
Roger