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[英]How to select rows from MySQL based on max value of a one column and grouping two other columns?
[英]How to select max and min of 1 column based on other 2 columns?
我正在尝试根据(A 列,B 列)唯一对组合获取 C 列中的最大和最小日期值。
假设我有一张像:
column_A column_B column_C
A 1 2019-08-11
A 1 2018-11-12
A 1 2017-11-12
A 11 2020-03-03
A 11 2021-01-10
A 11 2021-02-02
B 2 2020-11-11
B 2 2020-12-12
我想得到的输出是:
column_A column_B column_C
A 1 2019-08-11
A 1 2017-11-12
A 11 2020-03-03
A 11 2021-02-02
B 2 2020-11-11
B 2 2020-12-12
我的尝试查询运行了 20 分钟,但还没有输出(现在只是尝试从 C 列获取最大日期):
SELECT column_A, column_B, column_C FROM table_name
WHERE column_C IN (
SELECT MAX(column_C) FROM table_name
GROUP BY column_A, column_B
)
只需使用两个条件:
select t.*
from t
where column_c = (select max(t2.colc)
from table_name t2
where t2.column_A = t.column_A and t2.column_B = t.column_B
) or
column_c = (select min(t2.colc)
from table_name t2
where t2.column_A = t.column_A and t2.column_B = t.column_B
) ;
您可以使用两个按column_a
和column_b
分组的查询,一个是column_c
的最大值,另一个是column_c
,然后union all
它们column_c
:
SELECT column_a, column_b, MAX(column_c)
FROM table_name
GROUP BY column_a, column_b
UNION ALL
SELECT column_a, column_b, MIN(column_c)
FROM table_name
GROUP BY column_a, column_b
您可以创建一个临时视图和 GROUP BY 所需的列
select column_a,column_b,max(column_c) as max_column_c
from (select column_a,column_b,column_c,to_char(column,'YYYY') as year
from table_t) aa
group by column_a,column_b,year
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