What is a simple and efficient way to find rows with time-interval overlaps in SQL?

Question

I have two tables, both with start time and end time fields. I need to find, for each row in the first table, all of the rows in the second table where the time intervals in

Answer 1

SELECT * 
FROM table1,table2 
WHERE table2.start <= table1.end 
AND (table2.end IS NULL OR table2.end >= table1.start)