I want to get some data out of my database that is similar to a receipt you get at the supermarket (just an example which suits kinda good to my real situation).
For example you get the 2 (always only 2) products 1 and 3. These products are stored in a seperated product database.
Your shopping result is stored in one database containing all the details like time, location and so on AND in 2 columns (product_1, and product_2). Again this shopping situation is only a comparison to my real situation so I know that this would not be a good database structure for a shopping list.
So now I would like to get the Whole receipt but instead of printing the product IDs I would like to have the Name and for example the price on it.
If I had only one product I would use this query:
SELECT `list`.`time`, `list`.`location`, `prod`.`prod_name`, `prod`.`prod_price`
FROM `shopping_list` `list`, `products` `prod`
WHERE `list`.`product_1` = `prod`.`prod_id`
But since I have two products I cannot just go on with
AND `list`.`product_2` = `prod`.`prod_id`
But how do you achive what I would like to have?
Thank you very much,
Phil
You'll need to join to the product table twice
e.g.
SELECT
`list`.`time`,
`list`.`location`,
`prod1`.`prod_name` `prod_name1`,
`prod1`.`prod_price` `prod_price1` ,
`prod2`.`prod_name` `prod_name2`,
`prod2`.`prod_price` `prod_price2`
FROM `shopping_list` `list`
INNER JOIN `products` `prod1`
ON `list`.`product_1` = `prod1`.`prod_id`
INNER JOIN `products` `prod2`
ON `list`.`product_2` = `prod2`.`prod_id`
I'm not sure what your business rules are so you may need to convert the second INNER JOIN to a LEFT JOIN if they need to always select two products.
i don't know your exact situation but usually field names like product_1 and product_2 indicate bad database design. however if you really need that you need to join the products table twice.
select
*
from
list l
, product p1
, product p2
where
l.product_1 = p1.product_id
and l.product_2 = p2.product_id
(this is oracle syntax but i think it will work also in mysql).
hth.
The previous answers work well if you can parse out the two lines from 1 database result row. If you want two lines from the database you could do a UNION query:
SELECT `list`.`time`, `list`.`location`, `prod`.`prod_name`, `prod`.`prod_price`
FROM `shopping_list` `list`, `products` `prod`
WHERE `list`.`product_1` = `prod`.`prod_id`
UNION
SELECT `list`.`time`, `list`.`location`, `prod`.`prod_name`, `prod`.`prod_price`
FROM `shopping_list` `list`, `products` `prod`
WHERE `list`.`product_2` = `prod`.`prod_id`
Related
I've got a problem with MySQL select statement.
I have a table with different Department and statuses, there are 4 statuses for every department, but for each month there are not always every single status but I would like to show it in the analytics graph that there is '0'.
I have a problem with select statement that it shows only existing statuses ( of course :D ).
Is it possible to create temporary table with all of the Departments , Statuses and amount of statuses as 0, then update it by values from other select?
Select statement and screen how it looks in perfect situation, and how it looks in bad situation :
SELECT utd.Departament,uts.statusDef as statusoforder,Count(uts.statusDef) as Ilosc_Statusow
FROM ur_tasks_details utd
INNER JOIN ur_tasks_status uts on utd.StatusOfOrder = uts.statusNR
WHERE month = 'Sierpien'
GROUP BY uts.statusDef,utd.Departament
Perfect scenario, now bad scenario :
I've tried with "union" statements but i don't know if there is a possibility to take only "the highest value" for every department.
example :
I've also heard about
With CTE tables, but I don't really get how to use it. Would love to get some tips on it!
Thanks for your help.
Use a cross join to generate the rows you want. Then use a left join and aggregation to bring in the data:
select d.Departament, uts.statusDef as statusoforder,
Count(uts.statusDef) as Ilosc_Statusow
from (select distinct utd.Departament
from ur_tasks_details utd
) d cross join
ur_tasks_status uts left join
ur_tasks_details utd
on utd.Departament = d.Departament and
utd.StatusOfOrder = uts.statusNR and
utd.month = 'Sierpien'
group by uts.statusDef, d.Departament;
The first subquery should be your source of all the departments.
I also suspect that month is in the details table, so that should be part of the on clause.
Hi im trying to make a left join on this database.
Table category:
// `category` table has 3 columns
id,business_id (FK from business),category.
Table business:
// `business` table has 12 columns
id, name, etc (all info for that business)
What I need is to filter all the business that are Restaurants and join it to the respective business ID.
Problem is that each business have multiple category and when I do a select/join the result doesnt return DISTINCT businesses.
Here is one of the query i tried:
SELECT category.category,business.*
FROM category
INNER JOIN business
ON category.business_id = business.id;
I also tried left, right joins. But my pc is either taking forever or not working.
P.S the dataset is 8.6G
![database output]: https://i.imgur.com/eF4zYOr.png
Your query looks okay, but it is lacking that you are only looking for restaurants. However, firstly, I would make sure I have an index built on category.id
create index your_index_name on your_table_name(your_column_name);
Then you can simplify your query this way:
select a.id, a.category, b.* from category a left join business b on a.business_id=b.id WHERE a.category='Restaurants';
Even with that, a table that's 8.6G is going to take time. Since you said "pc" instead of "server" it might take a long time.
Try this
SELECT *
FROM Business b
WHERE EXISTS (
SELECT 1
FROM Category
WHERE category = 'Restaurants' AND business_id = b.id
)
I have a simple database with few tables (and some sample columns):
game (gm_id , game_name , company , desc)
plateform_master (p_id , plateform_name)
plateform_details (pd_id, gm_id, p_id, release_date)
Is there a way to create single SQL query which will return all game details with multiple plateform
Your question is not very clear. To which posts and categories are you referring yourself?
Here an example based on what I understood: Select all records from plateform_master and, for each of them, get its details from plateform_details. You can uncomment the where part in order to get one master record with its details. ("--" means comment in SQL)
select
pm.p_id
pd.*
from plateform_master as pm
inner join plateform_details as pd on pm.p_id = pd.p_id
-- where pm.p_id = 123
Sorry, my bad, it should be left join, not inner join!
With your changed requirements try this (not tested): Select all games and, for each one, get it's plateform_details and plateform_master correspondent values:
select
gm.gm_id,
gm.game_name,
gm.company,
pd.release_date,
pm.plateform_name
from game as gm
left join plateform_details as pd on pd.gm_id = gm.gm_id
left join plateform_master as pm on (pm.p_id = pd.p_id AND pd.gm_id = gm.gm_id)
-- WHERE CONDITIONS
;
Thanks for voting. I also wanted to tell you, that you have no many-to-many relationships here. You have just one-to-many. Many-to-many means the use of a middle table between two other ones.
I have 3 tables,Products, Languages and Products_translation.
How can I retrieve one Product and all translation at same time in one query ?
I have this
SELECT p.*, pt.description FROM Products p
LEFT JOIN Products_translation pt ON p.id=pt.product_id
LEFT JOIN Languages l ON pt.language =l.code
I have 3 languages, but it only retrieves one field name 'description' and I wanted it to return 3 (the number of languages), with something like description_en, description_es, description_fr
It's possible to make something like pt.description AS 'description'+'l.code' ?
This is a very common question and I'm fairly sure it's been answered many times (for example here: Mysql: joining tables for translation records). Anyway, if you have only 3 languages, just do this:
SELECT p.*, pt_en.description as description_en, pt_es.description as description_es, pt_fr.description as description_fr FROM Products p
LEFT JOIN Products_translation pt_en ON (p.id=pt.product_id and pt.language = 'en')
LEFT JOIN Products_translation pt_es ON (p.id=pt.product_id and pt.language = 'es')
LEFT JOIN Products_translation pt_fr ON (p.id=pt.product_id and pt.language = 'fr')
If you have more than 3, or a varying number, search pivoting or pivot table for more info. It's not easy to do in SQL so usually it's faster to just select your products, select all the translations of those products in a separate query, and construct the result you want outside of the database.
I'm aware of the INSERT INTO table_name QUERY; however, I'm unsure how to go about achieving the desired result in this case.
Here's a slightly contrived example to explain what I'm looking for, but I'm afraid I cannot put it more succiently.
I have two tables in a database designed for a hotel.
BOOKING and CUSTOMER_BOOKING
Where BOOKING contains PK_room_number, room_type, etc. and CUSTOMER_BOOKING contains FK_room_number, FK_cusomer_id
CUSTOMER_BOOKING is a linking table (many customers can make many bookings, and many bookings can consist of many customers).
Ultimately, in the application back-end I want to be able to list all rooms that have less than 3 customers associated with them. I could execute this a separate query and save the result in the server-side scripting.
However, a more elegant solution (from my point of view) is to store this within the BOOKING table itself. That is to add a column no_of_bookings that counts the number of times the current PK_room_number appears as the foreign key FK_room_number within the CUSTOMER_BOOKING table. And why do this instead? Because it would be impossible for me to write a single complicated query which will both include the information from all ROOMS, among other tables, and also count the occurrences of bookings, without excluding ROOMS that don't have any bookings. A very bad thing for a hotel website attempting to show free rooms!
So it would look like this
BOOKING: PK_room_number (104B) room_type (double) room_price (high), no_of_bookings (3)
BOOKING: PK_room_number (108C) room_type (single) room_price (low), no_of_bookings (1)
CUSTOMER_BOOKING: FK_room_number (104B) FK_customer_id (4312)
CUSTOMER_BOOKING: FK_room_number (104B) FK_customer_id (6372)
CUSTOMER_BOOKING: FK_room_number (104B) FK_customer_id (1112)
CUSTOMER_BOOKING: FK_room_number (108C) FK_customer_id (9181)
How would I go about creating this?
Because it would be impossible for me to write a single complicated
query which will both include the information from all ROOMS, among
other tables, and also count the occurrences of bookings, without
excluding ROOMS that don't have any bookings.
I wouldn't say it's impossible and unless you're running into performance issues, it's easier to implement than adding a new summary column:
select b.*, count(cb.room_number)
from bookings b
left join customer_booking cb on b.room_number = cb.room_number
group by b.room_number
Depending on your query may need to use a derived table containing the booking counts for each room instead instead
select b.*, coalesce(t1.number_of_bookings,0) number_of_bookings
from bookings b
left join (
select room_number, count(*) number_of_bookings
from customer_booking
group by room_number
) t1 on t1.room_number = b.room_number
You have to left join the derived table and select coalesce(t1.number_of_bookings,0) in case a room does not have any entries in the derived table (i.e. 0 bookings).
A summary column is a good idea when you're running into performance issues with counting the # of bookings each time. In that case I recommend creating insert and delete triggers on the customer_booking table that either increment or decrement the number_of_bookings column.
You could do it in a single straight select like this:
select DISTINCT
b1.room_pk,
c1.no_of_bookings
from cust_bookings b1,
(select room_pk, count(1) as no_of_bookings
from cust_bookings
group by room_pk) c1
where b1.room_pk = c1.room_pk
having c1.no_of_bookings < 3
Sorry i used my own table names to test it but you should figure it out easily enough. Also, the "having" line is only there to limit the rows returned to rooms with less than 3 bookings. If you remove that line you will get everything and could use the same sql to update a column on the bookings table if you still want to go that route.
Consider below solutions.
A simple aggregate query to count the customers per each booking:
SELECT b.PK_room_number, Count(c.FK_customer_id)
FROM Booking b
INNER JOIN Customer_Booking c ON b.PK_room_number = c.FK_room_number
GROUP BY b.PK_room_number
HAVING Count(c.FK_customer_id) < 3; # ADD 3 ROOM MAX FILTER
And if you intend to use a new column no_of_booking, here is an update query (using aggregate subquery) to run right after inserting new value from web frontend:
UPDATE Booking b
INNER JOIN
(SELECT b.PK_room_number, Count(c.FK_customer_id) As customercount
FROM Booking b
INNER JOIN Customer_Booking c ON b.PK_room_number = c.FK_room_number
GROUP BY b.PK_room_number) As r
ON b.PK_room_number = r.PK_room_number
SET b.no_of_booking = r.customercount;
the following generates a list showing all of the bookings and a flag of 0 or 1 if the the room has a customer for each of the rooms. it will display some rooms multiple times if there are multiple customers.
select BOOKING.*,
case CUSTOMER_BOOKING.FK_ROOM_NUMBER is null THEN 0 ELSE 1 END AS BOOKING_FLAG
from BOOKING LEFT OUTER JOIN CUSTOMER_BOOKING
ON BOOKING.PK_room_numer = CUSTOMER_BOOKING.FK_room_number
summing and grouping we arrive at:
select BOOKING.*,
SUM(case when CUSTOMER_BOOKING.FK_ROOM_NUMBER is null THEN 0 ELSE 1 END) AS BOOKING_COUNT
from BOOKING LEFT OUTER JOIN CUSTOMER_BOOKING
ON BOOKING.PK_room_number = CUSTOMER_BOOKING.FK_room_number
GROUP BY BOOKING.PK_room_number
there are at least two other solutions I can think of off the top of my head...