SQL-Get highest record from group at another table - sql

Question

I have read several answers to related questions but none of them can be applied to this case.
I have a table TableA where several groups are listed, with their score:
GROUP|SCORE
Blue | 0
Green| 0
Red | 0
Orange| 0
On another table TableB, I have the parts of each group and their individual score (status), which can have three different values:
- G (Good)
- A (Average)
- B (Bad)
So tableB is:
GROUP|PART|STATUS
Blue | 3H2| A
Blue | 4NQ| G
Blue | W9X| A
Green| 65D| G
Red | 73F| B
Red | 91G| A
I need to Update the score on TableA in the following way:
If the best status between the parts of the group is G, group score is 3
If the best status between the parts of the group is A, group score is 2
If the best status between the parts of the group is B, group score is 1
I have been a couple of days going around this and I can't find a solution. Thank you guys. Btw, I am using Access 2013.

Answer 1

As I have already mentioned in the comments: Don't store the score redundantly; it is implicit in tableB. And to get your database straight introduce a status table:
STATUS DESCRIPTION SCORE
G Good 3
A Avarage 2
B Bad 1
If you want to select the score for each color group use this query for instance:
select b.colorgroup, max(s.score) as maxscore
from tableb as b
join status as s on s.status = b.status
group by b.colorgroup;
Two alternative ways to write the same query:
select
colorgroup,
(
select max(score)
from status as s
where s.status = b.status
) as maxscore
from tableb as b;
and
select b.colorgroup, s.maxscore
from tableb as b
join
(
select status, max(score) as maxscore
from status
group by status
) as s on s.status = b.status;
(BTW: I called your group colorgroup because GROUP is a reserved name in SQL.)
UPDATE You say you cannot add a table to the database. So you must evaluate the score in the query itself unfortunately. In standard SQL you would use CASE WHEN, which MS Access doesn't feature. MS Access provides IIF instead:
select
colorgroup,
max(iif(status = 'G', 3, iif(status = 'A', 2, 1))) as maxscore
from tableb
group by colorgroup;
If you even must use the column in tableA and store redundantly, use:
update tablea as a
set score =
(
select
max(iif(status = 'G', 3, iif(status = 'A', 2, 1))) as maxscore
from tableb as b
where b.colorgroup = a.colorgroup
);

Answer 2

In SQL-Server you could do in following:
QUERY
update a
set a.SCORE = MaxSTATUS
from #a a
join (select GROUP_, MAX(case when b.STATUS_ = 'G' then 3
when b.STATUS_ = 'A' then 2
when b.STATUS_ = 'B' then 1
end) MaxSTATUS
from #b b
group by GROUP_
) b ON a.GROUP_ = b.GROUP_
select * from #a
SAMPLE DATA
CREATE TABLE #a
(
GROUP_ NVARCHAR(60),
SCORE INT
)
INSERT INTO #a VALUES
('Blue',0)
,('Green',0)
,('Red',0)
,('Orange',0)
CREATE TABLE #b
(
GROUP_ NVARCHAR(60),
PART NVARCHAR(60),
STATUS_ NVARCHAR(60),
)
INSERT INTO #b VALUES
('Blue','3H2','A')
,('Blue','4NQ','G')
,('Blue','W9X','A')
,('Green','65D','G')
,('Red','73F','B')
,('Red','91G','A')
OUPUT
GROUP_ SCORE
Blue 3
Green 3
Red 2
Orange 0