想咨询您一下,mysql的myisam机制中,一次写到文件中的数据块时多少字节呢?有限制嘛?reclength和length的关系是什么呢?谢谢~
int _mi_write_part_record(MI_INFO *info,
my_off_t filepos, /* points at empty block */
ulong length, /* length of block */
my_off_t next_filepos,/* Next empty block */
byte **record, /* pointer to record ptr */
ulong *reclength, /* length of *record */
select a.* from wcd a where 1 > (select count(*) from wcd where id = a.id and time > a.time) order by a.time desc不子查询没法实现吧