SQL語句執行的時候是有一定順序的。
1.from
先選擇一個表，構成一個結果集。
2.where
對結果集進行篩選，篩選出需要的信息形成新的結果集。
3.group by
對新的結果集分組。
4.having
篩選出想要的分組。
5.select
選擇列。
6.order by
當所有的條件都弄完了。最後排序。
explain select users.`mobile_num`, concat(users.`lastName` ,users.`firstName`) as userName, users.`company`,
(case `users`.`idPhotoCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `idPhotoCheckStatus`,
(case `users`.`driverLicenseCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `driverLicenseCheckStatus`,
(case `users`.`companyCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `companyCheckStatus`,
(case `users`.`unionCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `unionCheckStatus`,
ptrip_num, dtrip_num
from users
left join
(select count(passenger_trip.id) as ptrip_num, passenger_trip.`userId` from passenger_trip where passenger_trip.status != 'cancel' group by passenger_trip.`userId` ) as ptrip
on ptrip.userId = users.id
left join
(select count(driver_trip.id) as dtrip_num, driver_trip.`userId` from driver_trip where driver_trip.status != 'cancel' group by driver_trip.`userId` ) as dtrip
on dtrip.userId = users.id
where company != '上海獅博實業投資有限公司' and company != '88共享'
explain select users.`mobile_num`, concat(users.`lastName` ,users.`firstName`) as userName, users.`company`,
(case `users`.`idPhotoCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `idPhotoCheckStatus`,
(case `users`.`driverLicenseCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `driverLicenseCheckStatus`,
(case `users`.`companyCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `companyCheckStatus`,
(case `users`.`unionCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `unionCheckStatus`,
(select count(passenger_trip.id) from passenger_trip where passenger_trip.userId = users.id and passenger_trip.status != 'cancel') as ptrip_num,
(select count(driver_trip.id) from driver_trip where driver_trip.userId = users.id and driver_trip.status != 'cancel') as dtrip_num
from users
where company != '上海獅博實業投資有限公司' and company != '88共享'
explain select users.`mobile_num`, concat(users.`lastName` ,users.`firstName`) as userName, users.`company`,
(case `users`.`idPhotoCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `idPhotoCheckStatus`,
(case `users`.`driverLicenseCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `driverLicenseCheckStatus`,
(case `users`.`companyCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `companyCheckStatus`,
(case `users`.`unionCheckStatus` when '2' then '已認證' when '3' then '已駁回' else '待認證' end) as `unionCheckStatus`,
count(passenger_trip.id) as ptrip_num
from users
left join passenger_trip on passenger_trip.userId = users.id and passenger_trip.status != 'cancel'
left join driver_trip on driver_trip.`userId`=users.`id` and driver_trip.`status` != 'cancel'
where company != '上海獅博實業投資有限公司' and company != '88共享'