Fri, 01 Oct 2004
Airplay Exposes Videos Watched in Chrome's Incognito Mode
iOS may expose your guilty pleasures by showing the names of videos watched in
Chrome's Incognito mode.
After exiting incognito mode, the name of a video viewed is still shown.
Killing chrome removes the name of the video.
Clusty Asks "Which Hat?"
Clusty, the newest next Google, asks you which hat you're wearing after you do
a search by grouping related results into clusters. So you can search for eclipse, and it will
give you the option of seeing results related to lunar eclipses or software.
Under Customize!, they have a blogs channel, and even a slashdot channel.
Correct Use of FROM Clauses
There's an interesting
article by Stéphane Faroult on ONLamp about when to use subselects rather than JOINs
in SQL queries. He says that only tables from which you are returning columns
or those tables necessary to join such tables should appear in the FROM clause.
All other tables used to limit the rows returned should appear in subselects in
the WHERE clause. He rewrites
select distinct a.CUSTOMER_ID, a.CUSTOMER_NAME
from CUSTOMERS a,
ORDERS b
where a.ZIP_CODE in ...
and b.ORDERED_DATE >= ...
and b.CUSTOMER_ID = a.CUSTOMER_ID
order by a.CUSTOMER_NAME
as
select a.CUSTOMER_ID, a.CUSTOMER_NAME
from CUSTOMERS a
where a.ZIP_CODE in ...
and a.CUSTOMER_ID in (select b.CUSTOMER_ID
from ORDERS b
where b.ORDERED_DATE >= ...)
order by a.CUSTOMER_NAME
He also gives another way to rewrite the query as an uncorrelated subquery. (Read the article for an explanation of the difference between correlated and uncorrelated queries.)
Having done almost exclusively MySQL development, I have yet to ever use subselects, but I'll definitely keep Faroult's article in mind for when I do.
