jquery - 使用子查询选择其他记录

Question

我尝试列出所有客户记录的第一天订单

表客户

customer_id | customer_name
    1       +    John
    2       +    Brad

表格顺序

order_id  | customer_id | date
   1      +      1      + 2013-10-12 01:00:00
   2      +      1      + 2013-11-18 09:00:00
   3      +      2      + 2013-11-21 02:00:00

MySQL

$get_ch_raw = "select c.*, a.*, ch.* from `customers` c  left join `admin` a on 
a.admin_id=c.admin_id left join `call_history` ch on 
ch.customer_id=c.customers_id 
order by c.customers_id desc"

结果应该是这样的:

1       +    John    +   2013-10-12 01:00:00
2       +    Brad    +   2013-11-21 02:00:00

我不确定在这种情况下如何使用子查询来选择第一个订单。

Answer 1

应该这样做:

SELECT c.customer_id, c.customer_name, MIN(o.date) date FROM customers c
LEFT JOIN orders o USING (customer_id)
GROUP BY c.customer_id

fiddle here .