instance method fetch_check_constraints

# File activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb, line 797
        def fetch_check_constraints(tables)
          raise NotImplementedError unless supports_check_constraints?

          fetch_by_schema(tables) do |schema, group|
            names = quoted_table_names(group)

            sql = +<<~SQL
              SELECT tc.table_name AS 'table',
                     cc.constraint_name AS 'name',
                     cc.check_clause AS 'expression'
              FROM information_schema.check_constraints cc
              JOIN information_schema.table_constraints tc
              USING (constraint_schema, constraint_name)
              WHERE tc.table_schema = #{schema}
                AND tc.table_name IN (#{names})
                AND cc.constraint_schema = #{schema}
            SQL
            sql << " AND cc.table_name IN (#{names})" if mariadb?

            by_name = query_all(sql).group_by { |row| row["table"] }

            group.index_with { |table| build_check_constraints(table, rows_for(by_name, table)) }
          end
        end