Sql 如何使用重复但必要的元素简化表格？

我想知道每次服务的最后日期

我希望实现以下目标：

+-------------------+---------------------+------+------------+---------------+---------------+
|        Vin        |  Concesionario_Crm  |  OTS |   Fecha    |     Service   | Concesionario |
+-------------------+---------------------+------+------------+---------------+---------------+
| JAANLR55EE7102074 |   AUTOCONSA UIO     |   9  | 23/04/2019 | MANTENIMIENTO |  AUTOCONSA UIO|
+-------------------+---------------------+------+------------+---------------+---------------+
| JAANLR55EE7102074 |   AUTOCONSA UIO     |   9  | 10/09/2018 |    MECANICA   |  AUTOCONSA UIO|
+-------------------+---------------------+------+------------+---------------+---------------+

我尝试了这个，但它只是在所选服务具有最后日期时获取记录

Mantenimiento = "INSERT INTO SERVICIO SELECT DISTINCT t2.Mes_CRM, t2.Razón_social, t2.vin, t2.concesionario_crm, t1.ots, t1.fecha, t2.tipo_servicio, t2.concesionario FROM (SELECT max(t.Mes_CRM) AS Mes_CRM, t.vin, sum(t.ots) AS ots, max(t.fecha_salida) AS fecha FROM CASO AS t GROUP BY t.vin)  AS t1 INNER JOIN CASO AS t2 ON (t1.Mes_CRM = t2.Mes_CRM) AND (t1.fecha = t2.fecha_salida) AND (t1.vin = t2.vin) WHERE (t2.tipo_servicio = 'MANTENIMIENTO')"

---

如果将日期存储为日期，而不是分散在两列中，这将更简单。但您可以通过子查询来实现这一点：

select t.*,
       (select count(*)
        from CASE1 as t3
        where t3.vin = t.vin
       ) as cnt
from CASE1 as t
where not exists (select 1
                  from CASE1 as t2
                  where t2.vin = t.vin and
                        t2.fetcha_entrada > t.fetcha_entrada 
                 );

---

not exists

通过表示没有其他年份/月份具有更大的该

vin值来获取最近的年份/月份，您可以使用聚合子查询上的联接来解决此问题，例如：

select t2.vin, t2.concesionario_crm, t1.ots, t1.fecha, t2.concesionario
from
(
    select t.vin, sum(t.ots) as ots, max(t.fecha_entrada) as fecha
    from case1 t
    group by t.vin
) t1 
inner join case1 t2 on t1.vin = t2.vin and t1.fecha = f2.fecha_entrada

请不要破坏你的帖子。