Table Definitions
Table 1 (horizontal) This is a table of users
| id | name | phone |
---------------------
| 1 | Bob | 800 |
| 2 | Phil | 800 |
Table 2 (Vertical Table) This is a table of teams
| id | name |
------------------
| 1 | Donkey |
| 2 | Cat |
Table 3 (Vertical Table) This table is connecting the first two
| id | user_id | team_id |
--------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
My Goal
I would like to be able to query the data in such a way that i get the following back:
| id | name | phone | Donkey | Cat |
-------------------------------------
| 1 | Bob | 800 | 1 | 1 |
| 2 | Phil | 800 | 1 | Null |
This table would have my horizontal table data, then a combination of the other two vertical tables to create the appended columns. Where table 2 ends up being the column name headings. And the row valus are pulled from table three as a boolean.
You're chasing a pivot table:
select u.*,
sum(case when t1.name = 'Donkey' then 1 else 0 end) Donkey,
sum(case when t1.name = 'Cat' then 1 else 0 end) Cat
from users u
inner join user_team ut1
on u.id = ut1.user_id
inner join teams t1
on ut1.team_id = t1.id
group by name
demo: http://sqlfiddle.com/#!9/5fd33/7
Related
I am having trouble with an SQL query. I have two tables.
My first table:
+------------+-------------+---------------+
| id_mission | Some column | Other column |
+------------+-------------+---------------+
| 1 | ... | ... |
| 2 | ... | ... |
+------------+-------------+---------------+
My second table:
+------------+-------------+---------+
| id_mission | id_category | points |
+------------+-------------+---------+
| 1 | 1 | 3 |
| 1 | 2 | 4 |
| 1 | 3 | 4 |
| 1 | 4 | 8 |
| 2 | 1 | -4 |
| 2 | 2 | 3 |
| 2 | 3 | 1 |
| 2 | 4 | -7 |
+------------+-------------+---------+
And I would like to have this kind of result with my SELECT request
+------------+-------------+--------------+---------------+----------------+
| id_mission | Some column | Other column | id_category 1 | id_category X |
+------------+-------------+--------------+---------------+----------------+
| 1 | ... | ... | ... | ... |
| 2 | ... | ... | ... | ... |
+------------+-------------+--------------+---------------+----------------+
I have tried this with the first two column but it doesn't work, I also tried GROUP_CONCAT, it works but it's not the result I want.
SELECT m.id_mission ,mc.id_category 1,mc1.id_category 2
from mission m
left join mission_category mc on m.id_mission = mc.id_mission
left join mission_category mc1 on m.id_mission = mc1.id_mission
Can someone help me?
You can use conditional aggregation. Assuming that you want to pivot the points value per category:
select
t1.*,
max(case when t2.id_category = 1 then points end) category_1,
max(case when t2.id_category = 2 then points end) category_2,
max(case when t2.id_category = 3 then points end) category_3
from t1
inner join t2 on t2.id_mission = t1.id_mission
group by t1.id_mission
This assumes that id_mission is the primary key of t1 (else, you need to enumerate the columns you want in both the select and group by clauses).
I am not able to figure out how I can get the following result with one MySQL Query:
I have two tables:
shop_items
| id | description | price | active |
+----+-------------+-------+--------+
| 1 | product_1 | 5 | 1 |
+----+-------------+-------+--------+
| 2 | product_2 | 10 | 1 |
+----+-------------+-------+--------+
| 3 | product_3 | 15 | 0 |
+----+-------------+-------+--------+
inventory_items (the shop_items a user purchased)
| id | item_id | user_id | active |
+----+---------+---------+--------+
| 1 | 2 | 1 | 1 |
+----+---------+---------+--------+
| 2 | 1 | 1 | 0 |
+----+---------+---------+--------+
I want to see all shop_items where active = 1 including a row called purchased = 0 or 1 based on inventory_items -> matching user_id (where user_id = something) and active = 1
Example output based on the data from above tables -> where user_id = 1:
| item_id | price | description | purchased |
+---------+-------+-------------+-----------+
| 1 | 5 | product_1 | 0 |
+---------+-------+-------------+-----------+
| 2 | 10 | product_2 | 1 |
+---------+-------+-------------+-----------+
What query do I need for this output?
Please note: I only need the result from ONE user_id which I can change within the query :)
Test
SELECT shop_items.*, COALESCE(inventory_items.active, 0) purchased
FROM shop_items
LEFT JOIN inventory_items ON shop_items.id = inventory_items.item_id
AND user_id = 1
WHERE shop_items.active = 1
I have a table of products ids and keywords that looks like the following:
+------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| product_id | int(10) unsigned | YES | MUL | NULL | |
| keyword | varchar(255) | YES | | NULL | |
+------------+------------------+------+-----+---------+----------------+
This table simply stores product ids, and keywords associated with those products. So for example, it might contain:
+----+------------+---------+
| id | product_id | name |
+----+------------+---------+
| 1 | 1 | soft |
| 2 | 1 | red |
| 3 | 1 | leather |
| 4 | 2 | cloth |
| 5 | 2 | red |
| 6 | 2 | new |
| 7 | 3 | soft |
| 8 | 3 | red |
| 9 | 4 | blue |
+----+------------+---------+
In other words:
product 1 is soft, red, and leather.
product 2 is cloth, red and new.
Product 3 is red and soft,
product 4 is blue.
I need some way to take in a product ID, and get back a sorted list of product ids ranked by the number of common keywords
So for example, if I pass in product_id 1, I'd expect to get back:
+----+-------+------------+
| product_id | matches |
+------------+------------+
| 3 | 2 | (product 3 has two common keywords with product 1)
| 2 | 1 | (product 2 has one common keyword with product 1)
| 4 | 0 | (product 4 has no common keywords with product 1)
+------------+------------+
One option uses a self right outer join with conditional aggregation to count the number of matched names between, e.g. product ID 1, and all other product IDs:
SELECT t2.product_id,
SUM(CASE WHEN t1.name IS NOT NULL THEN 1 ELSE 0 END) AS matches
FROM yourTable t1
RIGHT JOIN yourTable t2
ON t1.name = t2.name AND
t1.product_id = 1
WHERE t2.product_id <> 1
GROUP BY t2.product_id
ORDER BY t2.product_id
Follow the link below for a running demo:
SQLFiddle
You need to use an outer join against the keywords for productid 1:
select y.productid, count(y2.keyword)
from yourtable y
left join (
select keyword from yourtable y2 where y2.productid = 1
) y2 on y.keyword = y2.keyword
where y.productid <> 1
group by y.productid
order by 2 desc
SQL Fiddle Demo
Results:
| productid | count(y2.keyword) |
|-----------|-------------------|
| 3 | 2 |
| 2 | 1 |
| 4 | 0 |
I've got two tables in my database. Table 1 is a list of "timelines" and their corresponding owners and title.
Table 2 is a list of users who have access to the timelines but are followers, not owners.
I'm trying to write a query that outputs the lineID's and corresponding titles that are linked to a userID in either of the two tables.
A query for userID 1 would ideally output:
1 a
2 b
3 c
6 f
Hopefully this isn't too confusing but the purpose is to fill a dynamically generated select box with the LineID and Title for a given UserID...
Table 1 ("owners")
--------------------------
| LineID | UserID | Title |
| 1 | 1 | a |
| 2 | 1 | b |
| 3 | 1 | c |
| 4 | 2 | d |
| 5 | 2 | e |
| 6 | 1 | f |
--------------------------
Table 2 ("followers")
----------------------------
| RowID | LineID | UserID |
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 3 | 1 |
| 4 | 3 | 2 |
| 5 | 2 | 2 |
| 6 | 6 | 1 |
----------------------------
I tried using:
SELECT title
FROM `lines`
LEFT JOIN follow
ON follow.user_id = lines.user_id
WHERE follow.user_id = 1
That ended up producing duplicate rows.
The output I need would ideally be an array consisting of all the lineID's and Titles associated with that userID.
select LineId, Title
from owners
where LineId in (select LineId from followers group by LineId )
order by owners.LineId
What I did was, I wanted each user to have their own "unique" numbering system. Instead of auto incrementing the item number by 1, I did it so that Bob's first item would start at #1 and Alice's number would also start at #1. The same goes for rooms and categories. I achieved this by creating "mapping" tables for items, rooms and categories.
The query below works, but I know it can definitely be refactored. I have primary keys in each table (on the "ids").
SELECT unique_item_id as item_id, item_name, category_name, item_value, room_name
FROM
users_items, users_map_item, users_room, users_map_room, users_category, users_map_category
WHERE
users_items.id = users_map_item.map_item_id AND
item_location = users_map_room.unique_room_id AND
users_map_room.map_room_id = users_room.room_id AND
users_map_room.map_user_id = 1 AND
item_category = users_map_category.unique_category_id AND
users_map_category.map_category_id = users_category.category_id AND
users_category.user_id = users_map_category.map_user_id AND
users_map_category.map_user_id = 1
ORDER BY item_name
users_items
| id | item_name | item_location |item_category |
--------------------------------------------------------
| 1 | item_a | 1 | 1 |
| 2 | item_b | 2 | 1 |
| 3 | item_c | 1 | 1 |
users_map_item
| map_item_id | map_user_id | unique_item_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
users_rooms
| id | room_name |
----------------------
| 1 | basement |
| 2 | kitchen |
| 3 | attic |
users_map_room
| map_room_id | map_user_id | unique_room_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
users_category
| id | room_name |
----------------------
| 1 | antiques |
| 2 | appliance |
| 3 | sporting goods |
users_map_category
| map_room_id | map_user_id | unique_category_id |
----------------------------------------------------
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
Rewriting your query with explicit JOIN conditions makes it more readable (while doing the same).
SELECT mi.unique_item_id AS item_id
, i.item_name
, c.category_name
, i.item_value
, r.room_name
FROM users_map_item mi
JOIN users_items i ON i.id = mi.map_item_id
JOIN users_map_room mr ON mr.unique_room_id = i.item_location
JOIN users_room r ON r.room_id = mr.map_room_id
JOIN users_map_category mc ON mc.unique_category_id = i.item_category
JOIN users_category c ON (c.user_id, c.category_id)
= (mc.map_user_id, mc.map_category_id)
WHERE mr.map_user_id = 1
AND mc.map_user_id = 1
ORDER BY i.item_name
The result is unchanged. Query plan should be the same. I see no way to improve the query further.
You should use LEFT [OUTER] JOIN instead of [INNER] JOIN if you want to keep rows in the result where no matching rows are found in the right hand table. You may want to move the additional WHERE clauses to the JOIN condition in this case, as it changes the outcome.