class ActiveRecord::SchemaMigration

:nodoc:
to be executed the next time.
number is inserted in to the ‘SchemaMigration.table_name` so it doesn’t need
have been applied to a given database. When a migration is run, its schema
This class is used to create a table that keeps track of which migrations

def all_versions 

def all_versions
  order(:version).pluck(:version)
end

def create_table 

def create_table
  unless connection.table_exists?(table_name)
    connection.create_table(table_name, id: false) do |t|
      t.string :version, **connection.internal_string_options_for_primary_key
    end
  end
end

def drop_table 

def drop_table
  connection.drop_table table_name, if_exists: true
end

def normalize_migration_number(number) 

def normalize_migration_number(number)
  "%.3d" % number.to_i
end

def normalized_versions 

def normalized_versions
  all_versions.map { |v| normalize_migration_number v }
end

def primary_key 

def primary_key
  "version"
end

def table_exists? 

def table_exists?
  connection.data_source_exists?(table_name)
end

def table_name 

def table_name
  "#{table_name_prefix}#{schema_migrations_table_name}#{table_name_suffix}"
end

def version 

def version
  super.to_i
end