title: Google spreadsheet creating unique IDs from informations in different columns
body: <p>I want to create unique ID's for every items in a Google spreadsheet. This ID has to reflect informations contained in 2 columns. I made a simpler version of my data and joined it as an image <a href="https://i.stack.imgur.com/UXRFb.png" rel="nofollow noreferrer">WhereImAt</a>. As you can see in the first column, I want people to be able to identify the "city", the "type" for each item in the spreadsheet and a number which make the entry unique.</p>
  
  <p>The actual spreadsheet as more than 2k items in it. The column "city" has 19 possible entries and the "type" has 12.</p>
  
  <p>For the moment the only formulas I can think of is "If()", but with so many variables, it looks impossible or way too complex. I'm sure there is something more efficient... </p>
  
  <p>Can anyone think of a better way to achieve my goal? </p>