MySQL query - NOT NULL

[Anon]

Hello,

I have a party guestlist that is in a MySQL database. I was recently trying to make a mailing list. I ran into a problem. Not all the people on the guestlist had an email address and also there were duplicate emails.

I couldn't figure out a query that would only display the records that had a value in the email field.

I also couldn't figure out a query to catch duplicates.

Any ideas?

-Arturo

[ace21]

select distinct email from tblguest where email is not NULL and email<>''

you need both b/c there is a difference between an entry that was written a '' and one that was never written to at all.

Ace21

[Anon]

Had an idea while reading... As I'm sure Ace21's idea would work, could the following also be used: "select distinct email from tblguest where email like '%@%'"

(Cant test as I'm at work, but I'm doing something similiar at home.)

[[deleted]]

Yes that would work, but it would not be as efficient. The LIKE '%@%' forces a sequencial scan, which is always slow.