SQL 查询 frouping - 以下如何工作？

Question

I am trying to get a Cutting Group within cutting list(CutGroup).

Master Table - Tab1:

enter image description here

I am looking sum (Qty) in each group (ID, GroupSLN, MaxLen, Len, Reminder) and keep each group structure(Group) as it is. This is code which I've tried so far:

SELECT        ID, GroupSLN , MaxLen, Len, Reminder ,Sum(Qty),   max(SLN) AS SLN
FROM          Prd300_OPT
            GROUP BY BarID,  Bar, Length, Reminder, BarSizeID, SessionID ,Cuts 
            ORDER BY SLN

Answer 1

The id and maxlen seem the columns of importance. Using a sub query I can downfill the maxlen and use that to join back to the main table in a sub query to get the sum of qty over id and maxlen.

drop table if exists t;
create table t
(id int,maxlen int,len int, reminder int,qty int,sln int auto_increment primary key);

insert into t (id,maxlen,len,reminder,qty) values
(1,100,1000,null,1),(1,null,1000,1100,null),
(2,200,2000,null,1),(2,null,2000,2100,null),
(2,200,2000,null,1),(2,null,2000,2100,null),
(2,200,2000,null,1),(2,null,2000,2100,null);

select id,maxlen,len,reminder,
        case when s.qty is not null then
            (select sum(qty) from t where t.id = s.id and t.maxlen = s.lastmaxlen)
        end as qty
from
(
select distinct
         id,maxlen,len,reminder,qty,
        case when maxlen is null then
        (select 
        maxlen from t t1 where t1.sln < t.sln and t1.maxlen > 0 order by sln desc limit 1) 
        else maxlen
        end as lastmaxlen 
from t
) s
;

+------+--------+------+----------+------+
| id   | maxlen | len  | reminder | qty  |
+------+--------+------+----------+------+
|    1 |    100 | 1000 |     NULL |    1 |
|    1 |   NULL | 1000 |     1100 | NULL |
|    2 |    200 | 2000 |     NULL |    3 |
|    2 |   NULL | 2000 |     2100 | NULL |
+------+--------+------+----------+------+
4 rows in set (0.00 sec)

Notice the use of the distinct clause to dedupe in the sub query.