I am running the following query to understand to get users' first attempt to answer a question listed next to their second attempt.
SELECT
s.id AS attempt_id_first, m.id AS attempt_id_second, s.user_id
FROM
attempt s
INNER JOIN attempt m on s.user_id = m.user_id
WHERE
s.id<m.id
I end up with this:
attempt_first attempt_second user_id
7 17 1
9 10 2
9 15 2
10 15 2
4 6 9
24 25 15
29 34 19
29 36 19
34 36 19
I would like to have a new column that counts the number of attempts by users so that:
7 17 1 1
9 10 2 3
9 15 2 3
10 15 2 3
4 6 9 1
24 25 15 1
29 34 19 3
29 36 19 3
34 36 19 3
I am sure this is trivial, but I cannot get it to work. Help anyone?
I think this is it: Just display the results, and throw in an extra count subquery:
select
userid,
id,
(select
count('x')
from
attempt x
where
x.userid = a.userid) as attempcount
from
attempt a
If you like to keep the first and second attempt in separate columns, you can of course embed the subselect in your original query.
It seems wrong, though. Firstly, you need to have at least two attemps, otherwise none will show. You can solve that by changing inner join to left join and move the condition in the where clause to that join. Secondly, the 'second attempt' is not the second attempt per say. Actually, for each of the attempts you get all next attempts. Look at the example of user 2. You accidentally get three rows (where there are three attemps), but you get attempt 9 and 10, as well as attempt 9 and 15 as well as 10 and 15. 9, 15 is incorrect, since 15 isn't the attempt that followed 9. The more attempts a user has, the more of these false results you will get.
If you want one attempt listed next to the next one, with the count, I would suggest:
SELECT s.user_id, s.id AS attempt_id_first,
(select s2.id
from attempt s2
where s2.user_id = s.user_id and
s2.id > s.id
order by s2.id
limit 1
) as attempt_id_second,
(select count(*)
from attempt s3
where s3.user_id = s.user_id
) as totalAttempts
FROM attempt s ;
This only lists each attempt once with the next one. The count is included as the last column.
Related
I have a MySQL table as below
ID SHEET_NUMBER DAYS RESULT
1 55201 9 10
2 55209 28 25.5
3 55209 28 27.9
4 38558 7 12
5 38552 5 19
6 38559 5 5
I want to select only rows with firstly matching sheet numbers & only if there if there is a matching pair of 28 days specimens
so if there is only one 28 day it will select nothing but if there is at least 2x 28 day it will get both rows
I'm totally lost, i know i should be using group by.. but i'm unsure of its use.
thankyou
Can you try the following query:
SELECT *
FROM test
WHERE sheet_number IN (
SELECT sheet_number
FROM test
WHERE days = 28
GROUP BY sheet_number
HAVING COUNT(*) >= 2
);
Here's the SQL Fiddle.
First, write a query that finds sheet_number with two or more rows with days value of 28.
SELECT d.sheet_number
FROM my_table_below d
WHERE d.days = 28
GROUP BY d.sheet_number
HAVING COUNT(1) > 1
With that query, we can use that as an inline view, and join back to the original table to find the matching rows:
SELECT t.*
FROM ( SELECT d.sheet_number
FROM my_table_below d
WHERE d.days = 28
GROUP BY d.sheet_number
HAVING COUNT(1) > 1
) m
JOIN my_table_below t
ON t.sheet_number = m.sheet_number
AND t.days = 28
ORDER BY t.sheet_number, t.id
Omit the condition t.days = 28 on the outer query, if the specification is to return all of the rows for the sheet_number, not just the rows with days=28. (The specification is a bit unclear.)
I have two tables.
One table records orderstock which has FK_stock and FK_orderNo
I want to count the number of orders each item of stock has. The following code works correctly to do this:
(1)
SELECT orderstock.FK_orderNo, Count(orderstock.FK_stock) AS CountOfFK_stock
FROM stock INNER JOIN orderstock ON stock.StockID = orderstock.FK_stock
GROUP BY orderdemo.FK_orderNo
However, I wish to add to this such that only stock items which are non perishable (stock.perishable=0) are listed. So something like
SELECT orderstock.FK_orderNo, Count(orderstock.FK_stock) AS CountOfFK_stock
FROM stock INNER JOIN orderstock ON stock.stockID = orderstock.FK_stock
WHERE stock.perishable=0
GROUP BY orderstock.FK_orderNo
How do I access information relating to the FK_stock to make this work? When I attempt to combine information from the stock table to this end, each item of stock is counted separately.
Results from (1)
FK_OrderNo CountOfFK_Stock
9 10
104 8
105 3
106 10
107 8
108 10
109 11
110 9
Desired results (something like):
FK_OrderNo CountOfFK_Stock
9 7
104 8
105 3
106 4
107 7
108 2
109 11
110 6
I guess you are looking for conditional count
Move the where clause filter to Count Aggregate and make the count aggregate to count the record only when stock.perishable = 0.
SELECT orderdemo.fk_orderno,
Count(CASE
WHEN stock.perishable = 0 THEN 1
END) AS nonperishable_count
FROM stock
INNER JOIN orderdemo
ON stock.studentid = orderdemo.fk_stock
GROUP BY orderdemo.fk_orderno
Count Aggregate can be replaced by SUM aggregate as well. Something like this
Sum(CASE
WHEN stock.perishable = 0 THEN 1
ELSE 0
END) AS nonperishable_count
My database tracks sections users have completed:
Table 'users':
id user_id sections_id
//
4 46 1
5 46 2
6 46 4
7 46 5
//
Table 'sections':
id header_id name
1 1 1/3
2 1 2/3
3 1 3/3
4 2 1/3
5 2 2/3
6 2 3/3
The following query
SELECT a.sections_id
,b.header_id
FROM users a
JOIN sections b
ON a.sections_id = b.id
WHERE a.user_id = 46;
// a.user_id can be just user_id, but added for clarity
Gives me:
sections_id header_id
1 1
2 1
4 2
5 2
What I want is max section ID per header for a particular user, so that I know which section I need to serve the user:
sections_id header_id
2 1
5 2
I'm assuming this is a max per group problem, but I can't quite get my head around the solution. I could throw all the data into my PHP and parse out from there, but it seems I should be able to do it via the SQL. TIA!
This is a simple group by query:
SELECT s.header_id, max(u.sections_id)
FROM users u JOIN
sections s
ON u.sections_id = s.id
WHERE u.user_id = 46
group by s.header_id;
I also changed your aliases to be the initials of the table. This makes the query much easier to follow.
Edit: SQLFiddle Here: http://sqlfiddle.com/#!2/dbb5a/2
You could add a group by clause with a max() function
SELECT max(a.sections_id)
,b.header_id
FROM users a
JOIN sections b
ON a.sections_id = b.id
WHERE a.user_id = 46
GROUP BY header_id;
I have the following query:
SELECT a.feeder_id, b.feeder_pr
FROM authors_article_feeders a
LEFT JOIN feeders b ON b.id = a.feeder_id
WHERE website_id =1
LIMIT 0 , 30
which results in:
feeder_id feeder_pr
18 2
18 2
18 2
18 2
32 6
What I need is to modify the above query so that it will manipulate this data so that the result would end up with a count of each feeder_pr, so in this case the result would be:
feeder_pr count
2 4
6 1
Any assistance is appreciated. If you have time please describe your solution so that I can learn from it while I'm at it.
Everything I've tried has ended in inaccurate results, usually with just one row instead of the expected 2.
You just need to add a GROUP BY And, you would not even need the joins
SELECT b.feeder_pr, COUNT(b.feeder_pr)
FROM feeders b
GROUP BY b.feeder_pr
SELECT b.feeder_pr, count(a.feeder_id) as count
FROM authors_article_feeders a
LEFT JOIN feeders b ON b.id = a.feeder_id
WHERE website_id =1
GROUP BY 1
I've tried a few of the similar SO questions, but I can't seem to figure it out.
On the first inner join, I only want to bring in DISTINCT function columns code and serial_id. So when I do my SUM selects, it calculates one per distinct. Ie there are multiple rows with the same func.code and func.serial_id. I only want 1 of them.
SELECT
sl.imp_id,
lat.version,
SUM(IF(lat.status = 'P',1,0)) AS powered,
SUM(IF(lat.status = 'F',1,0)) AS functional
FROM slots sl
INNER JOIN functions func ON sl.id = func.slot_id
INNER JOIN latest_status lat ON lat.code = func.code
AND lat.serial_id = func.serial_id
WHERE sl.id=55
GROUP BY sl.imp_id, lat.version
EDIT 2 - sample data explanation -------------------
slots - id, imp_id, name
functions - id, slot_id, code, serial_id
latest_status - id, code, serial_id, version, status
**slots**
id imp_id name
1 5 'the name'
2 5 'another name'
3 5 'name!'
4 5 'name!!'
5 5 'name!!!'
6 5 'testing'
7 5 'hi'
8 5 'test'
**functions**
id slot_id code serial_id
1 1 11HRK 10
2 2 22RMJ 11
3 3 26OLL 01
4 4 22RMJ 00
6 6 11HRK 10
7 7 11HRK 10
8 8 22RMJ 00
**latest_status**
id code serial_id version status
1 11HRK 10 1 F
1 11HRK 10 2 P
3 22RMJ 11 1 P
4 22RMJ 11 2 F
5 26OLL 01 1 F
6 26OLL 01 2 P
7 22RMJ 00 1 F
8 22RMJ 00 2 F
After running the query, the result should look like this:
imp_id version powered functional
5 1 1 3
5 2 2 2
The function table gets rolled up based on the code, serial_id. 1 row per code, serial_id.
It then gets joined onto the latest_status table based on the serial_id and code, which is a one (functions) to many (latest_status) relationship, so two rows come out of this, one for each version.
How about using DISTINCT?
SELECT
SUM(IF(lat.status = 'P',1,0)) AS powered,
SUM(IF(lat.status = 'F',1,0)) AS functional
FROM slots sl
INNER JOIN (Select DISTINCT id1, code, serial_id from functions) f On sl.rid = f.id1
INNER JOIN latest_status lat ON lat.code = f.code
AND lat.serial_id = f.serial_id
WHERE sl.id=55
GROUP BY sl.imp_id, lat.version
If you want only the distinct code and serial_id, you need to group by those not the imp_id and version. And end up with something like
SELECT
SUM(IF(lat.status = 'P',1,0)) AS powered,
SUM(IF(lat.status = 'F',1,0)) AS functional
FROM slots sl
INNER JOIN functions func ON sl.rid = func.id1
INNER JOIN latest_status lat ON lat.code = func.code
AND lat.serial_id = func.serial_id
WHERE sl.id=55
GROUP BY func.code, func.serial_id
However, this could all be rubish, without more data as tgo what some of those other columns are, but they dont seem to be the ones you wanted to group by.