Where A=1 AND A=2 returns 0 row problem - (Short Mysql question)

Question

I have the following table (id, Tag) with the following values

(1, 17)
(1, 31)
(2, 17)
(3, 31)

When I query the following

"SELECT id FROM table WHERE 1 AND Tag=17 AND Tag=31"

I expected it to return (id)

(1)

But it doesn't. (returns 0 row)

What's wrong here?

Answer 1

For any particular row the tag can't be both 17 and 31. You need

SELECT id 
FROM   table 
WHERE  Tag in (17, 31) 
GROUP  BY id 
HAVING COUNT(DISTINCT Tag) = 2  

Answer 2

Machines are logic and do what you asked them to do... your expectations are wrong in this case.

Tag 17 AND tag 31 conditions according to boolean math should be satisfied simultaneous to produce results.