SequenceDO?sequenceDO?=?sequenceDOMapper.getSequenceByName("order_info");
sequence?=?sequenceDO.getCurrentValue();
sequenceDO.setCurrentValue(sequenceDO.getStep()+sequenceDO.getCurrentValue());
sequenceDOMapper.updateByPrimaryKeySelective(sequenceDO);

這里在查詢的時(shí)候，加了for update可以保證查詢的時(shí)候只能返回一個(gè)current_value,但是如果，該進(jìn)程還未將sequenceDO插入，另一個(gè)進(jìn)程又到了查詢，那么。則兩個(gè)進(jìn)程的current_value不是一樣了么