title: big query sql alias
body: <p>I'm a student taking the coursera.org google data analytics course. I have recently completed a lesson on using aliases, I'm trying to understand this a little better. My most recent experience with coding before starting sql was 20 years ago in high school c++ class, so when I see that sql allows the use of aliases I think about defining variables. I realize tables and columns are not variables but, with biqquery sql and sgl in general is is possible to define aliases before your query, similar to defining all your variables before the body of your c++ code?
  Next, does my question even make sense, or am I off in left field?</p>