Question

编写查询以显示访问次数最多的客户名称

select customer_id,count(*)  from booking group by customer_id ;

使用此查询我获得了每位客户的访问次数，如下所示

CUSTOMER_ID,COUNT(*)
C001,6
C002,1
C003,1
C004,1
C005,4

但我想只显示c005，因为他已经访问了第二个最长时间

Answer 1

SELECT customer_id, COUNT(*)
FROM booking
GROUP BY customer_id
HAVING COUNT(*) <> (SELECT MAX(t.custCount)
                    FROM (SELECT COUNT(*) AS custCount
                          FROM booking
                          GROUP BY customer_id) t )
ORDER BY COUNT(*) DESC
LIMIT 1

作为旁注，如果有第二名的关系，这将不会起作用。在这种情况下，您使用上述查询作为WHERE子句中的条件，例如

SELECT customer_id
FROM booking
GROUP BY customer_id
HAVING COUNT(*) = (query given above)

Answer 2

您可以使用外部查询并过滤相同的内容，例如

select customer_id from (
select customer_id,
count(*) as datacount
from booking 
group by customer_id ) xxx
order by datacount desc
limit 1;

如何仅显示出现次数最高的值？

2 个答案: