def add_foreign_key_sql(from_table, to_table, options = {})
column = options[:column] || "#{to_table.to_s.singularize}_id"
foreign_key_name = foreign_key_name(from_table, column, options)
primary_key = options[:primary_key] || "id"
dependency = dependency_sql(options[:dependent])
sql =
"ADD CONSTRAINT #{quote_column_name(foreign_key_name)} " +
"FOREIGN KEY (#{quote_column_name(column)}) " +
"REFERENCES #{quote_table_name(ActiveRecord::Migrator.proper_table_name(to_table))}(#{primary_key})"
sql << " #{dependency}" if dependency.present?
sql << " #{options[:options]}" if options[:options]
sql
end