I'll try to explain it as simple as possible:
First some database structure with dummy data.
Structure
tb_spec_fk
feature value
-----------------
1 1
1 2
1 3
1 4
1 5
2 2
2 3
3 1
3 4
4 2
4 3
4 4
5 1
5 3
5 5
6 3
6 5
tb_spec_feature
feature_id filter
------------------
1 2
2 2
3 2
4 2
5 1
6 0
tb_spec_value
value_id name
----------------
1 10
2 20
3 30
4 40
5 50
Now, what I want is the follow result
Result
feature_id min_value max_value
---------------------------------
1 10 50
2 20 30
3 10 40
4 20 40
But how?
Logic
Get from the tb_spec_feature where "filter" equals 2 the highest and lowest values which are present in the tb_spec_value table and connected together trough the tb_spec_fk table.
My attemps
A lot! But I'll spare you :)
SELECT
f.feature_id AS feature_id,
MAX(value.name) AS max_value,
MIN(value.name) AS min_value
FROM tb_spec_feature AS f
JOIN tb_spec_fk AS fk ON f.feature_id=fk.feature
JOIN tb_spec_value AS value ON fk.value=value.id
WHERE f.filter=2
GROUP BY f.feature_id
The two JOIN statements "link" the a feature to a value. GROUP BY groups all rows with the same feature id, and then you can take the min or max or any other aggregate function on those columns.
Demo
Here is how you can do it
select
tsf.feature_id,
tsvl.name as Min_Value,
tsvr.name as Max_Value
from tb_spec_feature as tsf
inner join (select feature , MIN(value) MinV,MAX(value)MaxV from tb_spec_fk group by feature order by feature)as tsfkl on tsfkl.feature = tsf.feature_id
left join tb_spec_value as tsvl on tsvl.value_id = tsfkl.MinV
left join tb_spec_value as tsvr on tsvr.value_id = tsfkl.MaxV
where tsf.filter = 2
group by tsf.feature_id
Output
feature_id | Min_Value | Max_Value
---------------------------------
1 | 10 | 50
2 | 20 | 30
3 | 10 | 40
4 | 20 | 40
Fiddle Demo
Related
Sorry for my bad english)
Need help with mysql query.
There is a products table, which stores the base price for products that do not have attributes that the price depends on.
Table: product
product_id
product_name
price
1
T-shirt_1
10
2
T-shirt_2
12
10
T-shirt_10
18
15
Hat
10
There is a table of attribute values by which products are filtered.
Table: eav_ent
ent_id
product_id
attr_id
attr_value_id
1
1
1
2
2
1
1
4
3
1
1
19
4
1
2
25
5
1
2
34
6
2
2
23
7
2
3
56
Table: eav_ent_product_price
ent_product_price_id
product_id
price_name
price
1
1
T-shirt_1 size S
10
2
1
T-shirt_1 size M
15
3
1
T-shirt_1 size M with a zipper
20
4
2
T-shirt_2 size M
12
5
2
T-shirt_2 size M with a zipper
25
Table: eav_ent_product_price_attr
ent_product_price_attr_id
product_id
attr_value_id
ent_product_price_id
1
1
2
1
2
1
19
2
3
1
4
3
4
1
19
3
5
2
19
4
6
2
4
5
7
2
19
5
For each product, you can separately create prices depending on the combination of attributes, for example:
T-shirt_1 size S - 10 $
T-shirt_1 size M - 15 $
T-shirt_1 size M with a zipper - 20 $
Hat - $ 10 (base price)
How can I correctly filter products and display prices depending on the selected attributes, if they exist, or just display the base price?
What I tried:
SELECT a.* FROM(
SELECT p.* FROM product p
JOIN eav_ent en1 ON en1.product_id=p.product_id AND en1.attr_value_id=19
JOIN eav_ent en2 ON en2.product_id=p.product_id AND en2.attr_value_id=4
LEFT JOIN eav_ent_product_price ppi ... I don't know
WHERE 1 GROUP BY p.product_id
) a WHERE 1
I'm looking for some basic direction on how where to start looking to try and rank rows of a common key in a query.
Imagine I have a table like this:
user_id | account_id | score
1 A 10
1 B 20
2 C 10
2 D 20
2 E 30
What I'm hoping to do is add a rank column for relative to each user_id where the highest score gets the top rank:
user_id | account_id | score | rank
1 A 10 2
1 B 20 1
2 C 10 3
2 D 20 2
2 E 30 1
Just looking for some basic direction in terms of which way to head :/
You can use subquery
select
*,
(select count(1)+1 from your_table b where a.user_id=b.user_id and a.score<b.score) as rank
from your_table a
Output
1 A 10 2
1 B 20 1
2 C 10 3
2 D 20 2
2 E 30 1
Say I have a table called students
idStudent Name
1 Billy
2 Mariah
3 Chris
4 Mark
5 Sarah
and another table called tests
idTest score student_idstudent
1 50 1
2 100 1
3 90 2
4 100 3
5 45 4
is it possible to use a combination of a join and avg() to get a result like
idStudent avg_test
1 75
2 90
3 100
4 45
5 0
SELECT s.idStudent,
AVG(COALESCE(t.score, 0)) AS avg_test
FROM students s
LEFT JOIN tests t
ON s.idStudent = t.student_idStudent
GROUP BY s.idStudent
I have two tables, one of a list of competition results, and one with ELO ratings (based on previous competitions).
Fetching the list of competitors for an arbitrary competition is trivial enough, but I also need to get the most recent rating value for them.
score:
id | eventid | competitorid | position
1 1 1 1
2 1 2 2
3 1 3 3
4 2 2 1
5 2 3 2
6 3 1 1
7 3 3 2
8 3 2 3
rating:
id | competitorid | rating
1 1 1600
2 2 1500
3 3 1500
4 2 1600
5 3 1590
Expected output for a query against score.eventid = 3 would be
id | competitorid | position | rating
6 1 1 1600
7 3 2 1590
8 2 3 1600
At the moment my code looks like:
SELECT score.scoreID, score.competitorID, score.position,
rating.id, rating.rating
FROM score, rating
WHERE score.competitorid = rating.competitorid
AND score.eventid = 3
ORDER BY score.position
which gives an output of
id | competitorid | position | rating.id | rating
6 1 1 1 1600
7 3 2 2 1500
7 3 2 4 1590
8 2 3 3 1500
8 2 3 5 1600
basically it's showing the data from the score table for that correct event, but giving me a row for every rating available against that competitorID unfortunately I have no idea where to build in the DISTINCT statement or how to limit it to the most recent result.
MySQL noob, and managed DISTINCT statements, but not with joins. Unfortunately most previous questions seemed to deal with getting distinct results from a single table, which is not quite what I'm after. Thanks!
One way to get the rating is with a correlated subquery:
SELECT s.scoreID, s.eventID, s.competitorID, s.position,
(select r.rating
from rating r
where s.competitorID = r.competitorID
order by r.id desc
limit 1
) as rating
FROM score s
WHERE s.eventID = 3
ORDER BY s.position;
I'm not sure what ratingprid is, so this only includes the rating.
I need to order data according to order index from other table. and order the data with the same 'id' according to entry date.
i cant figure it out how to join data and order using mysql command.
Table1
id name order
1 Ali 1
2 Cenk 3
3 Tan 2
Table 2
id tid m date
1 232 msj1 3
2 434 msj2 2
1 453 msj4 1
3 455 msj5 2
2 541 msj6 4
1 234 msj7 2
3 132 msj8 6
Needed query result
id tid m date
1 453 msj4 1
1 234 msj7 2
1 232 msj1 3
3 455 msj5 2
3 132 msj8 6
2 434 msj2 2
2 541 msj6 4
This should work:
select t2.id, t2.tid, t2.m, t2.date
from t2
left join t1 on t2.id=t1.id
order by t1.order
This orders by the ordering field from table 1.