mysql 中 You can't specify target table for update in FROM clause错误

mysql中You can't specify target table <tbl> for update in FROM clause错误的意思是说，不能先select出同一表中的某些值，再update这个表(在同一语句中)。

update issue i set i.group_date =
(select t.groupDate from (SELECT
@cdate := i.commit_date input_date,
@last_sat := date_add(date_sub(date_sub(@cdate,interval day(@cdate)-1 day),interval 1 month), interval 6-date_format(date_sub(date_sub(@cdate,interval day(@cdate)-1 day),interval 1 month),'%w') day) last_sat,
@this_sat := date_add(date_sub(@cdate,interval day(@cdate)-1 day), interval 6-date_format(date_sub(@cdate,interval day(@cdate)-1 day),'%w') day) this_sat,
@next_sat := date_add(date_add(date_sub(@cdate,interval day(@cdate)-1 day),interval 1 month), interval 6-date_format(date_add(date_sub(@cdate,interval day(@cdate)-1 day),interval 1 month),'%w') day) next_sat,
@last_point := if(day(@last_sat)-3>0,date_sub(@last_sat,interval 7 day),@last_sat) last_point,
@this_point := if(day(@this_sat)-3>0,date_sub(@this_sat,interval 7 day),@this_sat) this_point,
@next_point := if(day(@next_sat)-3>0,date_sub(@next_sat,interval 7 day),@next_sat) next_point ,
case when @cdate >= @last_point and @cdate < @this_point then
concat(
'W',
datediff(@cdate,@last_point) div 7 + 1, '/',
year(@cdate),'-',
if(month(@last_sat)>=10,month(@last_sat),concat('0',month(@last_sat)))
)
when @cdate >=@this_point and @cdate < @next_point then
concat(
'W',
datediff(@cdate,@this_point) div 7 + 1,'/',
year(@cdate),'-',
if(month(@this_sat)>=10,month(@this_sat),concat('0',month(@this_sat))))
else
concat(
'W',
datediff(@cdate,@next_point) div 7 + 1,'/',
year(@cdate),'-',if(month(@next_sat)>=10,month(@next_sat),concat('0',month(@next_sat))))
end
as groupDate) t)

where i.id in (
select isus.id from (select isu.* from issue isu) isus
);