Optimize SQL that uses between clause

Question

Consider the following 2 tables:

Table A:
id
event_time

Table B
id
start_time
end_time

Every record in table A is mapped to exactly 1 reco

Answer 1

I see that you are doing a cross join of two tables. That is not very good, and DBMS will take a lot of time to execute that operation. Cross join is the most exepensive operation in SQL. The reason of so long time of execution could be this.

Do on that way, it could resolve...

SELECT A.id, B.id FROM A, B WHERE A.id = B.id AND A.event_time BETWEEN B.start_time AND B.end_time

I hope this help you :)