mysql选择按最大值分组并获取唯一行

将此数据保存在MySql表中：

unit_code                                   |       amount  |       effective_from
52599244-6a7f-408b-a1fc-41278a31af59        |       12000       |       7/1/2021
167e3920-daf0-4f24-ab61-d5efb22a37d0        |       12000       |       7/1/2021
ca8efdeb-817f-4ab9-a959-edef8663bcfa        |       12000       |       7/1/2021
463d5cd5-b30a-46a5-ae7e-95f6f6924edf        |       12000       |       7/1/2021
346264ad-4fa3-48d6-b3ca-830a0ff9a1e6        |       12000       |       7/1/2021
80c2fa42-be9e-4550-a377-04cd63468ba9        |       12000       |       7/1/2021
b2153987-2bff-4c91-9777-16a2f920b990        |       12000       |       7/1/2021
6c9769d9-6478-4698-a777-99d6141ade34        |       4500        |       7/1/2021
b57fcf7e-1403-4fcc-a2f6-70b235b7eea1        |       4500        |       7/1/2021
a67362ef-ff05-45bf-94f8-725d0cf030da        |       4500        |       7/1/2021
288ea5cf-8e1c-4d26-b891-b59579119853        |       4500        |       7/1/2021
3b0f137b-b965-450a-a729-70b50286fa43        |       4500        |       7/1/2021
c9f14429-92dc-4698-853d-7f8831bd30dd        |       4500        |       7/1/2021
be15e011-221b-45e1-a493-df5959546a54        |       4500        |       7/1/2021
8701bdeb-6948-405f-81c3-6958c1e6f727        |       4500        |       7/1/2021
68e4fd8e-6fc1-431d-9b75-0c9766129aa5        |       4500        |       7/1/2021
776b706d-bc19-416e-8b9c-e479b55d3be2        |       4500        |       7/1/2021
7ac72a15-7028-41c3-879b-a478198dd8be        |       4500        |       7/1/2021
06e93241-d08a-4f43-87a9-ceae07e05c80        |       4500        |       3/1/2021
09e46ea7-d0de-4c64-aa9c-a2886a5e7211        |       4500        |       7/1/2021
495c7790-a248-49db-90b6-1be1814f52c8        |       4500        |       7/1/2021
71fa2c19-6149-4e20-8562-9186da99ac68        |       4500        |       7/1/2021
08cb1844-0c38-4f76-8aed-9a5b2d4c0519        |       4500        |       7/1/2021
898a9228-8d70-4a4a-8330-6e68dfef96f7        |       4500        |       7/1/2021
1c12922b-48a2-4aea-8d3f-3c8a881ad835        |       4500        |       7/1/2021
7f6fbc36-9749-422c-8f58-6dd49171fde4        |       4500        |       7/1/2021
523a10ce-f334-45b0-a1cd-58ac57de80f7        |       4500        |       7/1/2021
167e3920-daf0-4f24-ab61-d5efb22a37d0        |       6700        |       7/1/2021
167e3920-daf0-4f24-ab61-d5efb22a37d0        |       11996       |       7/1/2021
167e3920-daf0-4f24-ab61-d5efb22a37d0        |       6800        |       8/1/2021
95363e75-7ee6-4202-b7b1-5f681d560355        |       10000       |       28/1/2021
cf8fe894-18d6-47ec-ad3e-84828003455e        |       10000       |       28/1/2021
1c684a35-812b-4107-8c3e-27859293f6d6        |       10000       |       28/6/2021
50c42b42-c889-41c0-a572-8075f1341ad1        |       10000       |       28/1/2021
35a9d086-1dec-4151-a8ab-21610a8752af        |       10000       |       28/1/2021
ebb6ab8b-d933-4ee6-966b-968155def517        |       10000       |       28/1/2021
a7d10c49-420d-4c75-a2c1-f48cc4fb159e        |       6000        |       25/2/2021
405272f0-a100-476a-8263-5856e090b561        |       12000       |       8/3/2021
ebe9571d-f7df-4dc8-bc50-230eac24dd6a        |       12000       |       8/3/2021
4f52d59a-090d-4a5c-ba39-d4352be57336        |       12000       |       8/3/2021
1d81b529-fb5f-42cd-b624-c1547614337f        |       12000       |       7/3/2021
1d81b529-fb5f-42cd-b624-c1547614337f        |       6788        |       9/3/2021
346264ad-4fa3-48d6-b3ca-830a0ff9a1e6        |       888         |       9/1/2021
06e93241-d08a-4f43-87a9-ceae07e05c80        |       669         |       13/3/2021

我想选择唯一的单位代码单位代码可以在表中的单位代码列中有多个事件，金额和日期的最大日期和日期等于或小于今天。 我正在尝试，但我甚至没有接近结果。

您可以使用行号来查找所需的行。例如：

select *
from (
  select *,
    row_number() over(partition by unit_code
                      order by effective_from desc) as rn
  from t
  where effective_from <= curdate()
) x
where rn = 1