However, in some cases, you will need to read cursors both forward and backward, in which case you should use scrollable cursor. 但某些情况下,您需要游标既能向前又能向后,此时需要使用可滚动游标。
Usually, the target sequences are palindromes, meaning they read the same backward and forward. 通常,它们的目标序列具有回文结构,即从反向读和从正向读它们都是一样的。