1' and '1' or '1

[Critters]

Hi
A user was able to log into my site using:
1' and '1' or '1
in the username and password box.

I ran the query 

SELECT * FROM members WHERE name = '1' and '1' or '1' AND password = '1' and '1' or '1'

And it returned all rows. Can someone explain to me why this happens, and if the steps I
took (replacing the ' with a blank space when the user submits the login form) is enough
to prevent a similar "hack"

Appreciate any feedback.
--
Dave