Do I need reset db after I switch branch?

dbst.fish

function dbst
  set first_branch 'master'
  set second_branch (git rev-parse --abbrev-ref HEAD)
  if test (echo $argv | wc -w) -ge 1
    set first_branch $argv[1]
  end
  if test (echo $argv | wc -w) -ge 2
    set second_branch $argv[2]
  end
  git diff $first_branch...$second_branch --name-only db/migrate
end