GROUP by move-out to improve SQL running speed

Data Sheet Dh_order_detail A total of 169,247 data

Raw SQL

Selectfrom_unixtime (order_time, '%h:%i ') ' Time ', City,district,left (company, 6) Company,goods_num,order_price,order _code,order_timefromdh_order_detailwhereprovince_id =                GROUP by                Order_codeorder Byorder_time DESCLIMIT 50

Running time 4 seconds more

Improved, move GROUP by outward

Select*from (Selectfrom_unixtime (order_time, '%h:%i ') ' Time ', City,district,left (company, 6) Company,goods_num,order _price,order_code,order_timefromdh_order_detailwhereprovince_id = 16ORDER byorder_time DESCLIMIT) OGROUP BYorder_ Code

Run time 0.049 seconds

GROUP by move-out to improve SQL running speed