I have four tables, like these:
items
| id | name | category |
-------------------------
| 1 | item1 | toy |
| 2 | item2 | toy |
| 3 | item3 | home |
-------------------------
items2
| id | name | category | size |
--------------------------------
| 1 | itemA | toy | s |
| 2 | itemB | home | l |
--------------------------------
prices
| items.id | price |
--------------------
| 1 | 10 |
| 1 | 15 |
| 2 | 20 |
| 3 | 25 |
| 3 | 20 |
--------------------
prices
| items2.id | price |
--------------------
| 1 | 15 |
| 2 | 50 |
| 2 | 40 |
--------------------
I need to get a result which have both, items and items2, with the MIN of each price. In this example the result should be something like this:
| id | name | category | size | minprice |
-------------------------------------------
| 1 | item1 | toy | null | 10 |
| 2 | item2 | toy | null | 20 |
| 3 | item3 | home | null | 20 |
| 1 | itemA | toy | s | 15 |
| 2 | itemB | home | l | 40 |
-------------------------------------------
I also should be able to ORDER BY minprice, but I'm sure when I know how to join them I can do that too.
Thanks in advance!
I would suggest that you merge the tables items and items2. If a field doesn't apply to an item (such as size in this case), that is what null is for.
I haven't tested that this works but you want something like:
SELECT i.id, name, category, null as size, min(prices.price) from items i
JOIN prices on prices.id = i.id
GROUP BY i.id, i.name, i.category, size
UNION ALL
SELECT i2.id, name, category, size, min(prices2.price) from items2 i2
JOIN prices2 on prices2.id = i2.id
GROUP BY i2.id, i2.name, i2.category, i2.size
From what I can tell, you are over complicating things. You only need one table. For tuples in the item relation where there is no size, simply mark it as null.
This is probably an oversimplification. If prices are "sales" or something similar, you could use a left join to build the relation you are looking for
so
SELECT i.id, i.name, i.category, i.size, p.price as min_price FROM items i LEFT JOIN price p where p.price <= 40 ORDER BY min_price
Related
I'm creating e-commerce web site using MySQL. I have successfully created and inserted data to database.
Here is my database schema
table: categories table: product_types
+----+--------------+ +----+-------------+------------+
| id | name | | id | category_id | name |
+----+--------------+ +----+-------------+------------+
| 1 | Electronics | | 1 | 1 | Smartphone |
| 2 | Fashion | | 2 | 1 | Speakers |
+----+--------------+ +----+-------------+------------+
table: products
+----+-----------------+-------------+-------------------+-------+
| id | product_type_id | category_id | name | price |
+----+-----------------+-------------+-------------------+-------+
| 1 | 1 | 1 | Samsung Galaxy A3 | 300 |
| 2 | 1 | 1 | Samsung Galaxy A7 | 400 |
+----+-----------------+-------------+-------------------+-------+
table: options table: option_values
+----+-----------------+-------+ +----+-----------+------------+
| id | product_type_id | name | | id | option_id | name |
+----+-----------------+-------+ +----+-----------+------------+
| 1 | 1 | RAM | | 1 | 1 | 512 MB |
| 2 | 1 | Screen| | 2 | 1 | 1 GB |
| 3 | 1 | OS | | 3 | 3 | Android 5 |
+----+-----------------+-------+ | 4 | 3 | Android 6 |
| 5 | 2 | HD |
| 6 | 2 | FHD |
+----+-----------+------------+
table: product_option_values
+----+------------+-----------+-----------------+
| id | product_id | option_id | option_value_id |
+----+------------+-----------+-----------------+
| 15 | 1 | 1 | 1 |
| 16 | 1 | 2 | 5 |
| 17 | 1 | 3 | 3 |
| 18 | 2 | 1 | 2 |
| 19 | 2 | 2 | 6 |
| 20 | 2 | 3 | 4 |
+----+------------+-----------+-----------------+
Search must trigger through name column of each table and return name and price from products table.
The problem is that I don't know how to perform full text search joining all that tables.
Is there any easy way to do it?
You need a query that LEFT JOINs on each table to search with a condition based on fulltext search function MATCH, with a WHERE clause to filter out non-matching records. The SELECT DISTINCT ensures that you will not see duplicates.
We need to adjust manually the JOIN criteria from each table to products : option_values is the most complicated case as it does not directly references products (an additional join on product_option_values is needed, aliased pov below.
SELECT DISTINCT p.name, p.price
FROM
products p
LEFT JOIN categories c
ON MATCH(c.name) AGAINST('foo' IN NATURAL LANGUAGE MODE)
AND c.id = p.category_id
LEFT JOIN product_types pt
ON MATCH(pt.name) AGAINST('foo' IN NATURAL LANGUAGE MODE)
AND pt.category_id = p.category_id
LEFT JOIN options o
ON MATCH(o.name) AGAINST('foo' IN NATURAL LANGUAGE MODE)
AND o.product_type_id = p.product_type_id
LEFT JOIN product_option_values pov
ON pov.product_id = p.id
LEFT JOIN option_values ov
ON MATCH(ov.name) AGAINST('foo' IN NATURAL LANGUAGE MODE)
AND ov.id = pov.option_value_id
WHERE
COALESCE(c.id, pt.id, o.id, ov.id) IS NOT NULL
My database looks like this, I have client accounts which are assigned to specific profiles, and I have profiles which are assigned to specific categories, like in this schema:
| categories | | profiles | | categories_map |
--------------- ------------- ----------------------------
| ID | name | | ID | name | | ID | profile_id | cat_id |
--------------- ------------- ----------------------------
| 1 | cat1 | | 1 | p1 | | 1 | 1 | 1 |
| 2 | cat2 | | 2 | p2 | | 2 | 2 | 1 |
| 3 | cat3 | | 3 | p3 | | 3 | 3 | 1 |
| 4 | p4 | | 4 | 1 | 2 |
| 5 | 3 | 2 |
| 6 | 4 | 3 |
| profiles_map |
-----------------------------
| ID | profile_id | acc_id |
-----------------------------
| 1 | 1 | 1 |
| 2 | 3 | 1 |
| 3 | 4 | 1 |
I need to get categories assigned to accounts - which means when I want to get categories for acc_id = 1, I should get categories with ID 2 and 3 ( category with ID 2 doesn't fit because it contains profile with ID 2 which isn't assigned to this account). I tried this query but it doesn't work
select cats.id from profiles_map map
right join categories_map catm on catm.profile_id = map.profile_id
right join categories cats on cats.id = catm.cat_id
where catm.profile_id in (select profile_id from profiles_map where acc_id = 1)
and map.acc_id = 1 group by cats.id;
Could anybody help me with this question?
Can you try this one?
SELECT DISTINCT C.ID
FROM profiles_map PM
INNER JOIN categories_map CM ON CM.profile_id = PM.profile_id
INNER JOIN categories C ON C.ID = CM.cat_id
WHERE PM.acc_id= 1
If you want to get only category id, Please try following query:
SELECT DISTINCT cm.cat_id FROM categories_map cm
WHERE cm.profile_id in
(SELECT profile_id FROM profiles_map WHERE acc_id = 1)
Or if want to get category name and id then , use following query:
SELECT cat.id,cat.name FROM categories cm
WHERE cat.id in (SELECT DISTINCT cm.cat_id FROM categories_map cm
WHERE cm.profile_id in
(SELECT pm.profile_id FROM profiles_map pm WHERE pm.acc_id = 1))
I have 3 tables to join and need some help to make it work, this is my schema:
donations:
+--------------------+------------+
| uid | amount | date |
+---------+----------+------------+
| 1 | 20 | 2013-10-10 |
| 2 | 5 | 2013-10-03 |
| 2 | 50 | 2013-09-25 |
| 2 | 5 | 2013-10-01 |
+---------+----------+------------+
users:
+----+------------+
| id | username |
+----+------------+
| 1 | rob |
| 2 | mike |
+----+------------+
causes:
+--------------------+------------+
| id | uid | cause | <missing cid (cause id)
+---------+----------+------------+
| 1 | 1 | stop war |
| 2 | 2 | love |
| 3 | 2 | hate |
| 4 | 2 | love |
+---------+----------+------------+
Result I want (data cropped for reading purposes)
+---------+-------------+---------+-------------+
| id | username | amount | cause |
+---------+-------------+---------+-------------+
| 1 | rob | 20 | stop war |
| 2 | mike | 5 | love |
+---------+-------------+-----------------------+
etc...
This is my current query, but returns double data:
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid)
EDIT: fixed sql schema on fiddle
http://sqlfiddle.com/#!2/0e06c/1 schema and data
How I can do this?
It seems your table's model is not right. There should be a relation between the Causes and Donations.
If not when you do your joins you will get duplicated rows.
For instance. Your model could look like this:
Donations
+--------------------+------------+
| uid | amount | date | causeId
+---------+----------+------------+
| 1 | 20 | 2013-10-10 | 1
| 2 | 5 | 2013-10-03 | 2
| 2 | 50 | 2013-09-25 | 3
| 2 | 5 | 2013-10-01 | 2
+---------+----------+------------+
causes:
+----------------------+
| id | cause |
+---------+------------+
| 1 | stop war |
| 2 | love |
| 3 | hate |
+---------+------------+
And the right query then should be this
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.id = tti.causeId)
Try this
SELECT CONCAT(i.username ,' ',i.first_name) `name`,
SUM(tti.amount),
t.cause AS tag_name
FROM users i
LEFT JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid)
GROUP BY i.id
Fiddle
You need to match the id from both the users and causes table at the same time, like so:
SELECT i.*, t.cause as tag_name
FROM users i
INNER JOIN donations tti ON (tti.uid = i.id)
INNER JOIN causes t ON (t.uid = tti.uid and t.id = i.id)
Apologies for formatting, I'm typing this on a phone.
Here is my Products table.
+---------+------------+-----------+
| item_id | item_order | item_name |
+---------+------------+-----------+
| 10 | | Item x |
| 12 | | Item b |
| 33 | | Item j |
| 39 | | Item k |
+---------+------------+-----------+
I want to run a sql query in phpMyAdmin so that item_order will increment as item_id number decreases. I want to arrange products on my Featured Products page by item_order. At a later time I'll rearrange numbers in 'item_order' column to give certain products more prominence, but for now here is how table will look after query update...
+---------+------------+-----------+
| item_id | item_order | item_name |
+---------+------------+-----------+
| 10 | 4 | Item x |
| 12 | 3 | Item b |
| 33 | 2 | Item j |
| 39 | 1 | Item k |
+---------+------------+-----------+
How about this?
SELECT *, (
SELECT COUNT(1) FROM Products pd WHERE pd.item_id >= p.item_id
) item_order
FROM Products p
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.