SQL Customer 和 Transaction 中有 2 个表，显示已完成最大交易数的客户详细信息

Question

以下是 table 属性：

客户Table：客户 ID、客户姓名、地址、电子邮件 ID 和手机号码。
交易Table：交易ID、交易类型、金额和客户ID。

Answer 1

您可以使用计算其交易次数的聚合查询加入客户 table：

select c.*, t.cnt
from customers c
inner join (select customerid, count(*) cnt from transactions group by customerid) t
    on t.customerid = c.customerid
order by t.cnt desc
limit 1

如果不需要在结果集中显示事务计数，也可以使用关联子查询进行过滤：

select c.*
from customers c
order by (select count(*) from transactions t where t.customerid = c.customerid) desc
limit 1

如果你想允许顶级关系，那么一种选择是使用 window 函数（仅在 MySQL 8.0 中可用）：

select c.*
from customers c
inner join (
    select customerid, count(*) cnt, rank() over(order by count(*) desc) rn
    from transactions 
    group by customerid
) t on t.customerid = c.customerid
where t.rn = 1

Answer 2

DECLARE @number_of_transactions INT = --(YOUR DESIRED MAXIMUM NUMBER OF TRANSACTION)

SELECT * FROM customer_table a INNER JOIN transaction_table b ON a.customer_id = b.customer_id WHERE COUNT(b.transaction_id) = @number_of_transactions
ORDER BY customer_id;

SQL Customer 和 Transaction 中有 2 个表，显示已完成最大交易数的客户详细信息

There are 2 tables in SQL Customer and Transaction, Display the customer details who has done maximum number of transactions

mysql

sql

count

subquery

sql-order-by