mysql语句速度慢

[sdfgrtyu]

SELECT *   
from table201611 as o1
where GZLX='通信中断'  and not exists(select * from table201611  where 
GZLX<>'通信中断' and
    UNIX_TIMESTAMP(STR_TO_DATE (DYSJ, '%Y%m%d %H%i%s'))
 between  UNIX_TIMESTAMP(STR_TO_DATE (o1.DYSJ, '%Y%m%d %H%i%s')) and   UNIX_TIMESTAMP(DATE_ADD(STR_TO_DATE (o1.DYSJ, '%Y%m%d %H%i%s'),INTERVAL 24 hour))     
and TZBH=o1.TZBH)

and UNIX_TIMESTAMP(STR_TO_DATE (o1.DYSJ, '%Y%m%d %H%i%s'))<> (select max(UNIX_TIMESTAMP(STR_TO_DATE (DYSJ, '%Y%m%d %H%i%s'))) from table201611  where TZBH=o1.TZBH)
and 
(select GZLX from table201611 where UNIX_TIMESTAMP(STR_TO_DATE (DYSJ, '%Y%m%d %H%i%s'))>=UNIX_TIMESTAMP(DATE_ADD(STR_TO_DATE (o1.DYSJ, '%Y%m%d %H%i%s'),INTERVAL 24 hour)) and TZBH=o1.TZBH  order by UNIX_TIMESTAMP(STR_TO_DATE (DYSJ, '%Y%m%d %H%i%s')) limit 1
)= o1.GZLX


group by TZBH
limit 1;

这条语句速度慢，怎么解决？

[sdfgrtyu]

引用 1 楼 rucypli 的回复:

首先把字段不要加函数封装 用不到索引

时间是varchar类型的

[rucypli]

首先把字段不要加函数封装 用不到索引

[ACMAIN_CHM]

以文本方式贴出(不要贴图!) explain select .... 及 show index from 以供分析