Multi-counter with SQLite

---

examples/sqlite/multi_counter_sqlite.cr

require "sqlite3"

db_file = "counter.db"
if !File.exists?(db_file)
  DB.open "sqlite3://#{db_file}" do |db|
    db.exec "CREATE TABLE counters (name TEXT, count INTEGER, UNIQUE(name))"
  end
end

DB.open "sqlite3://#{db_file}" do |db|
  if ARGV.size == 1
    name = ARGV[0]
    count = 0
    db.query "SELECT count FROM counters WHERE name=?", name do |rs|
      rs.each do
        count = rs.read(Int32)
      end
    end

    count += 1
    puts count

    if count == 1
      db.exec "INSERT INTO counters VALUES (?, ?)", name, count
    else
      db.exec "UPDATE counters SET count=? WHERE name=?", count, name
    end
  else
    db.query "SELECT name, count FROM counters ORDER BY name DESC" do |rs|
      puts "#{rs.column_name(0)} (#{rs.column_name(1)})"
      rs.each do
        puts "#{rs.read(String)} (#{rs.read(Int32)})"
      end
    end
  end
end

Unhandled exception issue: https://github.com/crystal-lang/crystal-sqlite3/issues/52