How do I do an "OR" in mySQL?

[Caesar]

Let's suppose that I have the following PHP code in one of my files.

$myselect = "select * FROM thread WHERE forumid<>5 ORDER BY lastpost DESC LIMIT 10";

How do I also exclude threads where they come from forumid 18 or 19?

I tried:

$myselect = "select * FROM thread WHERE forumid<>5 OR forumid<>18 or forumid<>19 ORDER BY lastpost DESC LIMIT 10";

but it wouldn't work. Can someone tell me how do I do it the right way?

[petesmc]

What error, or problem are you getting when you run that page.

To admin i've never seen the: <>
Thing before. What is it, if it means = then just use that.

[freakysid]

You want to select all the records except thos records with a forumid of 5,18 and 19? Is that right? You need to use logical AND not OR. If I am correct that sql statement will be returning all the records. Right?

$myselect = "SELECT *
             FROM thread
             WHERE forumid <> 5
             AND forumid <> 18
             AND forumid <> 19
             ORDER BY lastpost DESC 
             LIMIT 10"; 

With logical OR only one of the conditions needs to be true for the result to evaluate to true. So if you construct a truth table you can see that all records will evaluate to true:

   | <>5  | <> 18  | <> 19 | <>5  OR <> 18  OR <> 19 
5  |    F |     T   |      T  |  T
18 |    T |     F   |     T   |   T
19 |    T |     T   |     F   |   T

Hehe, I don't know if that looks like a table to you - it looks ok in my browser.

[freakysid]

Pete <> is another way of writing the != (not equal to) comparison operater in MySQL. It is also used in visual basic.

[petesmc]

Ok thanks, that changes everything!

-Peter

[DarkMonkey]

Thanks sid, I was wondering what that did as well.