Well, I'm using MYSQL and I cannot specify specific columns multiple times. I know that the following code is wrong but it is to better understand what I am trying to do.
Note: id_follow_book = id book
I need to specify in the same query, from id_follow_book select some id in specific and with some specific chapters. With IN it does not help me, because I would select the id to follow the books well, but then I would not pick the correct chapters for each follow-up. Exist the possibility that the user is not following a book or id_follow_book, maybe even none. What I'm trying to return those that are followed by the user.
SELECT id_follow_book, num_chapt
FROM Follow, Chapters
WHERE id_user = 1 AND
id_follow_book = id_chapter_book AND
(id_follow_book = 15 AND num_chapt = (10+1)) AND/OR
(id_follow_book = 25 AND num_chapt = (5+1)) AND/OR
(id_follow_book = 30 AND num_chapt = (23+1))
The sum numbers are variables.
I tried too with CASE WHEN, but I didn't achieve it. Thanks and sorry for my english.
Follow Chapters
id_follow_book id_user id_chapter_book num_chapt
30 1 30 6
25 1 30 5
13 1 30 4
21 1 25 24
25 23
Expected result:
id_follow_book num_chapt (this is last viewed chapt of user, this solutioned)
30 6
25 24
Try using IN operator:
SELECT id_follow_book, num_chapt
FROM Follow inner join Chapters on
id_follow_book = id_chapter_book
WHERE id_user = 1 AND
id_follow_book in( 15,25,30) AND num_chapt in(11,6,24)
Related
I want to have the sum of the beginning inventory of the entire year. The beginning inventory is based of the end_inventory of another month. The beginning_inventory_id contains the ID of another row which points to the end_inventory. How do I properly get the sum of the beginning_inventory of a certain year when it's based of another row's end_inventory. I have the following table
id
time_period
beginning_inventory_id
end_inventory
gross_sales
1
2020-09-01
null
1000
500
2
2020-10-01
1
2000
500
3
2020-11-01
2
3000
500
4
2020-12-01
3
4000
500
5
2021-01-01
4
5000
500
I have the following SQL query
SELECT SUM(a.gross_sales) as gross_sales, SUM(a.end_inventory) as end_inventory,
(SELECT SUM(b.end_inventory) FROM fs_summary as b WHERE a.beginning_inventory_id = b.id) as beginning_inventory
FROM fs_summary as a
WHERE YEAR(a.time_period) = 2020
Output I would like to generate is:
beginning_inventory = 6000
end_inventory = 10000
gross_sales = 2000
Instead, I am getting null on the beginning_inventory.
Any help would be great!
I am Assuming that you want to retrieve data from 1 table with self join.
SELECT SUM(a.gross_sales),SUM(a.end_inventory),SUM(b.end_inventory)
FROM fs_summary a, fs_aummary b
WHERE b.id=a.beginning_inventory_id AND YEAR(a.time_period) = 2020
using self join can help you in this situation
EDIT: You can also write this script as,
SELECT SUM(a.gross_sales),SUM(a.end_inventory),SUM(b.end_inventory)
FROM fs_summary a
INNER JOIN fs_aummary b
ON b.id=a.beginning_inventory_id
WHERE YEAR(a.time_period) = 2020
Using self-join SQL you can achieve your result instead of sub-queries.
You should specify the same table with two different names. Your query looks as below
select sum(virtual_tb.end_inventory) as 'beginning_inventory', sum(org_tb.end_inventory) as 'end_inventory', sum(org_tb.gross_sales) as 'gross_sales'
from fs_summary org_tb left join fs_aummary virtual_tb on (virtual_tb.beginning_inventory_id = org_tb.id)
where year(org_tb.time_period) = 2020;
(Approx Output)
beginning_inventory
end_inventory
gross_sales
6000
10000
2000
I have a table users and some other tables like images and products
Table users:
user_id user_name
1 andrew
2 lutz
3 sophie
4 michael
5 peter
6 oscor
7 anton
8 billy
9 henry
10 jon
Tables images:
user_id img_type img_url
1 0 url1
1 1 url4
2 0 url5
7 0 url7
8 0 url8
9 1 url9
Table Products
user_id prod_id
1 5
1 55
2 555
8 5555
9 5
9 55
I use this kind of SELECT:
SELECT * FROM
(SELECT user.user_id,user.user_name, img.img_type, prod.prod_id FROM
users
LEFT JOIN images img ON img.user_id = users.user_id
LEFT JOIN products prod ON prod.user_id = users.user_id
WHERE user.user_id <= 5) AS users
ORDER BY user.user_id ASC
The result should be the following output. Due to performance improvements, I use ORDER BY and an inner select. If I put a LIMIT 5 within the inner or outer select, things won't work. MySQL will hard LIMIT the results to 5. However I need the LIMIT of 5 (pagination) found unique user_id results which would lead to 9 in this case.
Can I use maybe an if-statement to push an array with found user_id and break/finish up the select when the array consist of 5 UIDs? Or can I modify somehow the select?
user_id user_name img_type prod_id
1 andrew 0 5
1 andrew 1 5
1 andrew 0 55
1 andrew 1 55
2 lutz 0 5
2 lutz 0 55
3 sophie null null
4 michael null null
5 peter null null
results: 9
LIMIT 5 and user_id <= 5 do not necessarily give you the same results. One reason: There are multiple rows (after the JOINs) for user_id = 1. This is because there can be multiple images and/or multiple products for a given 'user'.
So, first decide which you want.
LIMIT without ORDER BY gives you an arbitrary set of rows. (Yeah, it is somewhat predictable, but you should not depend on it.)
ORDER BY + LIMIT usually implies gathering all the potentially relevant rows, sorting them, then doing the "limit". There are sometimes ways around this sluggishness.
LEFT leads to the NULLs you got; did you want that?
What do you want pagination to do if you are displaying 5 items per page, but user 1 has 6 images? You need to think about this edge case before we can help you with a solution. Maybe you want all of user 1 on a page, even if it exceeds 5? Maybe you want to break in the middle of '1'; but then we need an unambiguous way to know where to continue from for the next page.
Probably any viable solution will not use nested SELECTs. As you are finding out, it leads to "errors". Think of it this way: First find all the rows you need to display on all the pages, then carve out 5 for the current page.
Here are some more musings on pagination: http://mysql.rjweb.org/doc.php/pagination
At first I would like greet all Users and apologize for my english :).
I'm new user on this forum.
I have a question about MySQL queries.
I have table Items with let say 2 columns for example itemsID and ItemsQty.
itemsID ItemsQty
11 2
12 3
13 3
15 5
16 1
I need select itemsID but duplicated as many times as indicated in column ItemsQty.
itemsID ItemsQty
11 2
11 2
12 3
12 3
12 3
13 3
13 3
13 3
15 5
15 5
15 5
15 5
15 5
16 1
I tried that query:
SELECT items.itemsID, items.itemsQty
FROM base.items
LEFT OUTER JOIN
(
SELECT items.itemsQty AS Qty FROM base.items
) AS Numbers ON items.itemsQty <=Numbers.Qty
ORDER BY items.itemsID;
but it doesn't work correctly.
Thanks in advance for help.
SQL answer - Option 1
You need another table called numbers with the numbers 1 up to the maximum for ItemsQuantity
Table: NUMBERS
1
2
3
4
5
......
max number for ItemsQuantity
Then the following SELECT statement will work
SELECT ItemsID, ItemsQty
FROM originaltable
JOIN numbers
ON originaltable.ItemsQty >= numbers.number
ORDER BY ItemsID, number
See this fiddle -> you should always set-up a fiddle like this when you can - it makes everyone's life easier!!!
code answer - option 2
MySQL probably won't do what you want 'cleanly' without a second table (although some clever person might know how)
What is wrong with doing it with script?
Just run a SELECT itemsID, ItemsQty FROM table
Then when looping through the result just do (pseudo code as no language specified)
newArray = array(); // new array
While Rows Returned from database{ //loop all rows returned
loop number of times in column 'ItemsQty'{
newArray -> add 'ItemsID'
}
}//end of while loop
This will give you a new array
0 => 11
1 => 11
2 => 12
3 => 12
4 => 12
5 => 13
etc.
Select DISTINCT items.itemsID, items.itemsQty From base.items left outer join (select items.itemsQty as Qty from base.items) As Numbers On items.itemsQty <=Numbers.Qty
order by items.itemsID;
Use DISTINCT to remove duplicates. Read more here - http://dev.mysql.com/doc/refman/5.0/en/select.html
It seems like I understood what you asked differently than everyone else so I hope I answer you question. What I would basically do is -
create a new table for those changes.
Create a mysql procedure which given a line in the original table add new lines to the new table - http://dev.mysql.com/doc/refman/5.6/en/loop.html
Run this procedure for each line in the original table.
try this to get distinct values from both columns
SELECT DISTINCT itemsID FROM items
UNION
SELECT DISTINCT itemsQty FROM items
i have a table with around 1 128 910 rows and now my SQL statement is starting to run very slow.
My table looks like this:
SU_Id SU_User SU_Skill SU_Value SU_Date
int(10) int(10) int(10) float int(10)
1 1 23 45.34 1300978612
2 1 23 48.51 1300978865
3 1 23 47.21 1300979203
4 3 23 61.01 1300979245
5 2 23 38.93 1300979412
6 1 17 12.76 1300979712
7 2 23 65.30 1300979998
As seen in SU_Skill a user can have more then one entry with the same skill number. SU_Value hold the value of a skill, it can go up and down. SU_Date holds the date when a value was added.
I want a SQL statement that selects the 20 currently highest values of a skill. The following SQL statement is what i use today but it is slow and i think there is a better way of doing it.
SELECT DISTINCT SU_User AS Player,
(SELECT SU_Value FROM WOU__SkillUploads WHERE SU_User = Player AND SU_Skill = 23 ORDER BY SU_Date DESC LIMIT 1) AS Value
FROM WOU__SkillUploads
WHERE SU_Skill = 23
ORDER BY Value DESC LIMIT 20
Is there a faster way? Thanks for reading my question!
Sub-selects are very slow, especially in the way you're using this.
Rewrite this as a JOIN. In this case, because you want all records from SkillUploads where SU_SKILL = 23, this should probably be a RIGHT JOIN.
Can the same user be in the results multiple times? This may work for you.
SELECT SU_USER, MAX(SU_VALUE)
FROM WOU_SKILLUploads
WHERE SU_SKILL=23
GROUP BY SU_USER
ORDER BY MAX(SU_VALUE) DESC
LIMIT 20
I need help with a MySQL query. We have a database (~10K rows) which I have simplified down to this problem.
We have 7 truck drivers who visit 3 out of a possible 9 locations, daily. Each day they visit exactly 3 different locations and each day they can visit different locations than the previous day. Here are representative tables:
Table: Drivers
id name
10 Abe
11 Bob
12 Cal
13 Deb
14 Eve
15 Fab
16 Guy
Table: Locations
id day address driver.id
1 1 Oak 10
2 1 Elm 10
3 1 4th 10
4 1 Oak 16
5 1 4th 16
6 1 Toy 16
7 1 Toy 11
8 1 5th 11
9 1 Law 11
10 2 Oak 11
11 2 4th 11
12 2 Toy 11
.........
We have data for a full year and we need to find out how many times each "route" is visited over a year, sorted from most to least.
From my high school math, I believe there are 9!/(6!3!) route combinations, or 84 in total. I want do something like:
Get count of routes where route addresses = 'Oak' and 'Elm' and '4th'
then run again
where route addresses = 'Oak' and 'Elm' and '5th'
then again and again, etc.Then sort the route counts, descending. But I don't want to do it 84 times. Is there a way to do this?
I'd be looking at GROUP_CONCAT
SELECT t.day
, t.driver
, GROUP_CONCAT(t.address ORDER BY t.address)
FROM mytable t
GROUP
BY t.day
, t.driver
What's not clear here, if there's an order to the stops on the route. Does the sequence make a difference, and how to we tell what the sequence is? To ask that a different way, consider these two routes:
('Oak','Elm','4th') and ('Elm','4th','Oak')
Are these equivalent (because it's the same set of stops) or are they different (because they are in a different sequence)?
If sequence of stops on the route distinguishes it from other routes with the same stops (in a different order), then replace the ORDER BY t.address with ORDER BY t.id or whatever expression gives the sequence of the stops.
Some caveats with GROUP_CONCAT: the maximum length is limited by the setting of group_concat_max_len and max_allowed_packet variables. Also, the comma used as the separator... if we combine strings that contain commas, then in our result, we can't reliably distinguish between 'a,b'+'c' and 'a'+'b,c'
We can use that query as an inline view, and get a count of the the number of rows with identical routes:
SELECT c.route
, COUNT(*) AS cnt
FROM ( SELECT t.day
, t.driver
, GROUP_CONCAT(t.address ORDER BY t.address) AS route
FROM mytable t
GROUP
BY t.day
, t.driver
) c
GROUP
BY c.route
ORDER
BY cnt DESC