1581. 进店却未进行过交易的顾客

https://leetcode.cn/problems/customer-who-visited-but-did-not-make-any-transactions/description/?envType=study-plan-v2&envId=sql-free-50

sql
# Write your MySQL query statement below
select vis.customer_id,sum(if((tra.transaction_id is null), 1,0)) count_no_trans 
from visits vis
left join Transactions tra 
on vis.visit_id=tra.visit_id
group by vis.customer_id
having count_no_trans >0;

197. 上升的温度

https://leetcode.cn/problems/rising-temperature/description/?envType=study-plan-v2&envId=sql-free-50

sql
# Write your MySQL query statement below
select w2.id
from Weather w2
join Weather w1
on datediff(w2.recordDate,w1.recordDate)=1 
where w2.Temperature > w1.Temperature;