-- Database schema
| Album : AlbumId [ INT ] primary_key , Title [ TEXT ] , ArtistId [ INT ] Album.ArtistId = Artist.ArtistId | Artist : ArtistId [ INT ] primary_key , Name [ TEXT ] | Customer : CustomerId [ INT ] primary_key , FirstName [ TEXT ] , LastName [ TEXT ] , Company [ TEXT ] , Address [ TEXT ] , City [ TEXT ] , State [ TEXT ] , Country [ TEXT ] , PostalCode [ TEXT ] , Phone [ TEXT ] , Fax [ TEXT ] , Email [ TEXT ] , SupportRepId [ INT ] Customer.SupportRepId = Employee.EmployeeId | Employee : EmployeeId [ INT ] primary_key , LastName [ TEXT ] , FirstName [ TEXT ] , Title [ TEXT ] , ReportsTo [ INT ] Employee.ReportsTo = Employee.EmployeeId , BirthDate [ TEXT ] , HireDate [ TEXT ] , Address [ TEXT ] , City [ TEXT ] , State [ TEXT ] , Country [ TEXT ] , PostalCode [ TEXT ] , Phone [ TEXT ] , Fax [ TEXT ] , Email [ TEXT ] | Genre : GenreId [ INT ] primary_key , Name [ TEXT ] | Invoice : InvoiceId [ INT ] primary_key , CustomerId [ INT ] Invoice.CustomerId = Customer.CustomerId , InvoiceDate [ TEXT ] , BillingAddress [ TEXT ] , BillingCity [ TEXT ] , BillingState [ TEXT ] , BillingCountry [ TEXT ] , BillingPostalCode [ TEXT ] , Total [ INT ] | InvoiceLine : InvoiceLineId [ INT ] primary_key , InvoiceId [ INT ] InvoiceLine.InvoiceId = Invoice.InvoiceId , TrackId [ INT ] InvoiceLine.TrackId = Track.TrackId , UnitPrice [ INT ] , Quantity [ INT ] | MediaType : MediaTypeId [ INT ] primary_key , Name [ TEXT ] | Playlist : PlaylistId [ INT ] primary_key , Name [ TEXT ] | PlaylistTrack : PlaylistId [ INT ] primary_key PlaylistTrack.PlaylistId = Playlist.PlaylistId , TrackId [ INT ] PlaylistTrack.TrackId = Track.TrackId | Track : TrackId [ INT ] primary_key , Name [ TEXT ] , AlbumId [ INT ] Track.AlbumId = Album.AlbumId , MediaTypeId [ INT ] Track.MediaTypeId = MediaType.MediaTypeId , GenreId [ INT ] Track.GenreId = Genre.GenreId , Composer [ TEXT ] , Milliseconds [ INT ] , Bytes [ INT ] , UnitPrice [ INT ] |
-- -- How many distinct cities does the employees live in?

SELECT COUNT(DISTINCT city) FROM EMPLOYEE;