```ruby
# encoding: UTF-8
#
# Truncate or delete all data from an SQL database.
#
#     $ rake db:truncate
#     $ rake db:drop_tables

require 'database_cleaner'

namespace :db do
  desc "Truncate all tables"
  task truncate: :establish_connection do
    DatabaseCleaner.strategy = :truncation
    DatabaseCleaner.clean
  end

  desc "Drop all tables"
  task drop_tables: :establish_connection do
    ActiveRecord::Base.connection.tables.each do |table|
      ActiveRecord::Base.connection.drop_table table
    end
  end

  # Faster than depending on :environment
  task establish_connection: "db:load_config" do
    ActiveRecord::Base.establish_connection
  end

  # DEPRECATED
  # Alias to keep compatibility between rateaux v1.4.0 and v1.5.0
  task delete: :drop_tables

  # DEPRECATED
  # Undocumented alias. This is a joke, don't use this.
  task sandra: :delete
end
```

Add force: :cascade to drop_tables
user
```ruby
# encoding: UTF-8
#
# Truncate or delete all data from an SQL database.
#
#     $ rake db:truncate
#     $ rake db:drop_tables

require 'database_cleaner'

namespace :db do
  desc "Truncate all tables"
  task truncate: :establish_connection do
    DatabaseCleaner.strategy = :truncation
    DatabaseCleaner.clean
  end

  desc "Drop all tables"
  task drop_tables: :establish_connection do
    ActiveRecord::Base.connection.tables.each do |table|
      ActiveRecord::Base.connection.drop_table table,
                                               force: :cascade,
                                               if_exists: true
    end
  end

  # Faster than depending on :environment
  task establish_connection: "db:load_config" do
    ActiveRecord::Base.establish_connection
  end

  # DEPRECATED
  # Alias to keep compatibility between rateaux v1.4.0 and v1.5.0
  task delete: :drop_tables

  # DEPRECATED
  # Undocumented alias. This is a joke, don't use this.
  task sandra: :delete
end
```
assistant