it's very, very common. the company i work at doesn't fire people for showing up intoxicated though, they just force you to attend therapy.
one time I got black out drunk, went to bed at 3 am after puking all over my room, i got up and went to work at 10 (arrived one hour late) the security guard pulled me to a side and said i had to take the test in the doctors office. they made me breathe into a tube and I passed lol but the doctor could tell I was hangover and he told me to stop doing it so from then on I only drink on weekends