mysql刷题记录（3）

[呼延海]

175. 组合两个表

# Write your MySQL query statement below
select firstName,lastName,city,state
from Person 
left join Address
on Address.personId=Person.personId;

 比较简单的多表查询，需要注意的是这里select后的查询信息都是直接写出来的，因为在两个表中并没有同名的列，如果有同名的列需要在前面加上 ' 列名. ' 

1581. 进店却未进行过交易的顾客

# Write your MySQL query statement below
select 
    customer_id,count(customer_id) count_no_trans
from
    visits v
left join
    transactions t
    on v.visit_id=t.visit_id
where amount is null
group by customer_id;

 1148. 文章浏览 I

# Write your MySQL query statement below
SELECT DISTINCT author_id AS id
FROM  Views
WHERE author_id = viewer_id
ORDER BY author_id

 

目录

175. 组合两个表

1581. 进店却未进行过交易的顾客

 1148. 文章浏览 I

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