mysql - 在选择中选择另一个表的第一条记录 - MYSQL

Question

我正在尝试查询列出所有客户，并获取最后的评论和 单个查询中的history_client表中该评论的日期，以便列出它。

select a.id_client,a.name,a.lastname,(select b.date_created,b.comentary 
from history_of_client b where a.id_client = b.id_client_asociate) from clients_main_table

Answer 1

您可以在历史表上的 id_client 的 max(date_created) 上使用内部联接并联接

SELECT a.id_client,a.name,a.lastname, h.commentary
FROM clients_main_table a 
INNER join (
  select b.id_client_asociate, max(b.date_created) max_date
  from history_of_client 
  group by  b.id_client_asociate ) t on t.id_client_asociate = a.id_client 
INNER JOIN history_of_client h on h.id_client_asociate = t.id_client_asociate 
      and h.date_created = t.max_date