I'd like to ask some question about query.
This is my case:
Structure Table
codenumber varchar (PK)
prize varchar
batchno double
category varchar
Sample Data On Database:
Code Prize BatchNumber Category
1000000231 TRY AGAIN 1 A
1000000238 TRY AGAIN 2 A
1000000376 TRY AGAIN 3 A
1000000473 TRY AGAIN 4 A
1000000934 50 5 A
1000001281 50 6 B
1000001894 50 7 B
1000002014 TRY AGAIN 8 B
1000002831 TRY AGAIN 9 B
1000003123 TRY AGAIN 10 B
1000003158 TRY AGAIN 11 C
1000003224 TRY AGAIN 12 C
1000003524 TRY AGAIN 13 C
1000003598 50 14 C
1000003616 TRY AGAIN 15 C
1000003657 TRY AGAIN 16 A
1000003959 50 17 A
1000004289 TRY AGAIN 18 A
1000004529 TRY AGAIN 19 A
1000004853 TRY AGAIN 20 A
1000005683 TRY AGAIN 21 B
1000005728 100 22 B
1000005816 TRY AGAIN 23 B
1000006325 TRY AGAIN 24 B
I wanted to get the Minimum and Maximum batch number for each 5 rows.
Then how to get the query result like below:
Category MinBatch MaxBatch
A 1 5
B 6 10
C 11 15
A 16 20
B 21 24
Please Help Thanks
Presuming that batch represents the ordering for determining groups of 5, you can do this with variables:
select category, min(batch), max(batch)
from (select s.*, (#rn := #rn + 1) as rn
from structure s cross join
(select #rn := 0) params
order by batch
) s
group by floor((rn - 1) / 5)
order by min(batch);
Actually, if you know the batches are consecutive with no gaps and start at 1:
select category, min(batch), max(batch)
from structure s
group by floor((batch - 1) / 5)
order by min(batch);
Below query will give you the result
select category, min(batchnumber)as 'MinBatch', max(batchnumber)as 'MaxBatch'
from tablename order group by (category)
Related
I have table A
uid dt val_A
10 04/09/2012 34
10 08/09/2012 35
10 10/09/2012 36
100 04/09/2012 40
100 08/09/2012 41
and table B
uid date val_B
10 04/09/2012 1
10 05/09/2012 1
10 06/09/2012 2
10 07/09/2012 2
10 08/09/2012 1
100 07/09/2012 1
100 07/09/2012 3
I want to join them to get table C. I want to join them on uid. Furthermore I want to have a new column val_C which holds the average of val_B where date in B is greater or equal than the corresponding row-value dt in A AND less than the next higher dt value for this uid in table A. It means I want to aggregate the values in B based on date ranges defined in A. The joined table should look like this:
uid dt val_A val_C
10 04/09/2012 34 1.5
10 08/09/2012 35 1
10 10/09/2012 36 0
100 04/09/2012 40 2
100 08/09/2012 41 0
How can this be achieved?
//EDIT
How could a more generalized solution look like where all dates in B2 which are greater than the greatest date in A are being joined & aggregated to the greatest date in A. B2:
uid date val_B
10 04/09/2012 1
10 05/09/2012 1
10 06/09/2012 2
10 07/09/2012 2
10 08/09/2012 1
100 07/09/2012 1
100 07/09/2012 3
100 10/09/2012 4
100 11/09/2012 2
Desired output C2:
uid dt val_A val_C
10 04/09/2012 34 1.5
10 08/09/2012 35 1
10 10/09/2012 36 0
100 04/09/2012 40 2
100 08/09/2012 41 3
If you're on MySQL v8+ that supports LEAD() function, then you can try this:
WITH cte AS (
SELECT uid, dt, val_A,
IFNULL(LEAD(dt) OVER (PARTITION BY uid ORDER BY uid, dt),dt) dtRg
FROM tableA)
SELECT cte.uid, cte.dt, cte.val_A,
AVG(val_B) AS val_C
FROM cte
LEFT JOIN tableB tb1
ON cte.uid=tb1.uid
AND tb1.dt >= cte.dt
AND tb1.dt < cte.dtRg
GROUP BY cte.uid, cte.dt, cte.val_A
The query in common table expression (cte):
SELECT uid, dt, val_A,
IFNULL(LEAD(dt) OVER (PARTITION BY uid ORDER BY uid, dt),dt) dtRg
FROM tableA
will give you a result like this:
As you can see, the dtRg column is generated using LEAD() function which takes the next row dt value according to the ORDER BY. Read more about LEAD() here.
After that, join the cte with tableB on matching uid and where tableB.dt is the same or bigger than the existing tableA.dt - which is now as cte.dt, but lower than cte.dtRg - which is the next date in tableA that was generated by LEAD(). And finally adding AVG(val_B) AS val_C
Demo fiddle
On older MySQL version, you can try this:
SELECT tA.uid, tA.dt, tA.val_A,
AVG(val_B) AS val_C
FROM
(SELECT uid, dt, val_A,
(SELECT dt FROM tableA ta1
WHERE ta1.uid=ta2.uid
AND ta1.dt > ta2.dt LIMIT 1) AS dtRg
FROM tableA ta2) tA
LEFT JOIN tableB tB
ON tA.uid=tB.uid
AND tB.dt >= tA.dt
AND tB.dt < tA.dtRg
GROUP BY tA.uid, tA.dt, tA.val_A;
The difference are as following:
Instead of using LEAD(), it uses correlated subquery in SELECT to get the next dt value of next row in the same uid.
Instead of common table expression, it uses a derived table.
Fiddle for MySQL v5.7 version
I'm trying to figure out how to Select a specific number of rows from a MySQL table based on WHERE clause. I have a table with 10 dummy users, I want to get 2 previous and 2 next users of specific user with their ranks.
user_id | points
==================
10 200
4 130
2 540
13 230
15 900
11 300
3 600
17 110
20 140
1 430
5 800
I achieved adding a column for ranking like:
user_id | points | rank
===========================
15 900 1
5 800 2
3 600 3
2 540 4
1 430 5
11 300 6
13 230 7
10 200 8
20 140 9
4 130 10
17 110 11
But the problem is that I want only 5 rows. Suppose I'm retrieving data for user with user_id = 11. The output should look like this:
user_id | points | rank
===========================
2 540 4
1 430 5
11 300 6
13 230 7
10 200 8
where user_id = 11 is in the centre with 2 rows above and 2 below. I have tried nesting UNIONS and SELECT statements but nothing seems to work properly.
Here's a suggestion if you're on MySQL 8+:
WITH cte AS (
SELECT user_id, points,
ROW_NUMBER() OVER (ORDER BY points DESC) AS Rnk
FROM mytable)
SELECT cte2.user_id,
cte2.points,
cte2.Rnk
FROM cte cte1
JOIN cte cte2
ON cte1.user_id=11
AND cte2.Rnk >= cte1.Rnk-2
AND cte2.Rnk <= cte1.Rnk+2
Using common table expression (cte) then do a self join with condition of user_id=11 as base to get the Rnk value of -2 and +2.
Demo fiddle
Since you're on older MySQL version, here's what I can suggest:
SET #uid := 11;
SET #Rnk := (SELECT Rnk
FROM
(SELECT user_id, points,
#r := #r+1 AS Rnk
FROM mytable
CROSS JOIN (SELECT #r := 0) r
ORDER BY points DESC) v
WHERE user_id = #uid);
SELECT user_id, points, Rnk
FROM
(SELECT user_id, points,
#r := #r+1 AS Rnk
FROM mytable
CROSS JOIN (SELECT #r := 0) r
ORDER BY points DESC) v
WHERE Rnk >= #Rnk-2
AND Rnk <= #Rnk+2;
If you will only use user_id as base, then the only part here you need to change is the SET #uid. The remaining queries are just fulfilling your condition of getting two positions above and below the rank retrieved according to the user_id. The base query in SET #Rnk is the same as the base query for the last one. The idea is to assign #Rnk variable with Rnk position of user_id=11 then use it in WHERE condition for the last query.
I'm not aware if there's any online fiddle still using MySQL 5.1 but here's probably the closest version to it, MySQL 5.5 demo fiddle.
In MySql I need to select top student in every class in a school in termid=10 to get discount for next term enrollment .
Please notice that total is not in table(I put in below for clearing problem)
I have this workbook table for all students workbook:
id studentid classid exam1 exam2 total termid
1 2 11 20 40 60 10
2 1 22 40 20 60 10
3 4 11 40 20 60 10
4 5 33 10 60 70 10
5 7 22 10 40 50 10
6 8 11 10 30 40 10
7 9 33 20 45 65 10
8 11 11 null null null 10
9 12 54 null null null 02
10 13 58 null null null 02
1st challenge is : exam1 and exam2 are VARCHAR and total is not in table (as i explained).
2nd challenge is : as you can see in id=8 std #11 has not numbers
3rd challenge is : may be two students have top level so they must be in result.
I need result as :
id studentid classid exam1 exam2 total termid
1 2 11 20 40 60 10
3 4 11 40 20 60 10
4 5 33 10 60 70 10
2 1 22 40 20 60 10
i have this query but not work good as i mention.
SELECT DISTINCT id,studentid,classid,exam1,exam2,total,termid ,(CAST(exam1 AS DECIMAL(9,2))+CAST(exam2 AS DECIMAL(9,2))) FROM workbook WHERE ClassId = '10';
You can get the total for the students by just adding the values (MySQL will convert the values to numbers). The following gets the max total for each class:
select w.classid, max(coalesce(w.exam1, 0) + coalesce(w.exam2, 0)) as maxtotal
from workbook w
group by w.classid;
You can then join this back to the original data to get information about the best students:
select w.*, coalesce(w.exam1, 0) + coalesce(w.exam2, 0) as total
from workbook w join
(select w.classid, max(coalesce(w.exam1, 0) + coalesce(w.exam2, 0)) as maxtotal
from workbook w
group by w.classid
) ww
on w.classid = ww.classid and (coalesce(w.exam1, 0) + coalesce(w.exam2, 0)) = ww.maxtotal;
Another approach is to join the table with itself. You find out the max for each class and then join all students of this class which match the class max:
max for each class (included in the final statement already):
SELECT classid, MAX(CAST(exam1 AS UNSIGNED) + CAST(exam2 AS UNSIGNED)) as 'maxtotal'
FROM students
WHERE NOT ISNULL(exam1)
AND NOT ISNULL(exam2)
GROUP BY classid
The complete statement:
SELECT s2.*, s1.maxtotal
FROM (SELECT classid, MAX(CAST(exam1 AS UNSIGNED) + CAST(exam2 AS UNSIGNED)) as 'maxtotal'
FROM students
WHERE NOT ISNULL(exam1)
AND NOT ISNULL(exam2)
GROUP BY classid) s1
JOIN students s2 ON s1.classid = s2.classid
WHERE s1.maxtotal = (CAST(s2.exam1 AS UNSIGNED) + CAST(s2.exam2 AS UNSIGNED));
SQL Fiddle: http://sqlfiddle.com/#!2/9f117/1
Use a simple Group by Statement:
SELECT
studentid,
classid,
max(coalesce(exam1,0)) as max_exam_1,
max(coalesce(exam2,0)) as max_exam_2,
sum(coalesce(exam1,0) + coalesce(exam2,0)) as sum_exam_total,
termid
FROM
workbook
WHERE
termid=10
GROUP BY
1,2
ORDER BY
5
Try something like this:
SELECT id,studentid,classid,exam1,exam2,(CAST(exam1 AS DECIMAL(9,2))+CAST(exam2 AS DECIMAL(9,2))) AS total,termid FROM `workbook` WHERE ((CAST(exam1 AS DECIMAL(9,2))+CAST(exam2 AS DECIMAL(9,2)))) > 50
Thanks all my friends
I think combine between 2 answer in above is best :
SELECT s2.*, s1.maxtotal
FROM (SELECT ClassId, MAX(
coalesce(exam1,0)+
coalesce(exam2,0)
) as 'maxtotal'
FROM workbook
WHERE
(
termid = '11'
)
GROUP BY ClassId) s1
JOIN workbook s2 ON s1.ClassId = s2.ClassId
WHERE s1.maxtotal = (
coalesce(exam1,0)+
coalesce(exam2,0)
) AND (s1.maxtotal >'75');
last line is good for s1.maxtotal=0 (some times student scores have not be entered and all equals 0 so all will shown as best students) or some times we need minimum score (to enroll in next term).
So thanks all
Assume I have a table like this:
id pay
-- ---
1 10
2 20
3 30
4 40
5 50
6 60
I want to create a view from table above with this result:
id pay paid_before
-- --- -------------
1 10 0
2 20 10
3 30 30
4 40 60
5 50 100
6 60 150
which "paid_before" is sum of pay rows that have smaller id.
How could I do this job?
This accomplishes what you want.
SELECT p1.id,p1.pay, sum(p2.pay) as Paid_Before FROM PAYMENTS P1 LEFT JOIN
PAYMENTS P2 ON p1.id > p2.id
GROUP BY p1.id, p1.pay
See this sql fiddle
In MySQL, this is most efficiently done with variables:
select p.id, p.pay, (#p := #p + p.pay) - p.pay as PaidBefore
from payments p cross join
(select #p := 0) vars
order by id;
Although this is not standard SQL (which I usually prefer), that is okay. The standard SQL solution is to use cumulative sum:
select p.id, p.pay, sum(p.pay) over (order by p.id) - p.pay as PaidBefore
from payments p;
Many databases support this syntax, but not MySQL.
The SQL Fiddle (courtesy of Atilla) is here.
I have the following data
user_id days date
88 2 2013-08-25
88 4 2013-08-23
88 18 2013-08-5
88 1 2013-08-4
88 2 2013-08-2
73 11 2013-08-2
299 4 2013-08-2
12 983 2013-08-2
I'm trying to get all recent rows (order by DATE desc) for a specific user_id , until the SUM of days column is bigger than X. For example in this case if X=7 I would get the three first rows with SUM(days)=24.
Try this. Here you will use a local variable that will count the sums in the subquery.
select
user_id,
days,
date
from
(
select
user_id,
days,
date,
#sum_days := #sum_days + days as sum_days
from
myTable
order by
date desc
) t
cross join (select #sum_days := 0) const -- resetting your #sum_days var.
where
sum_days < X -- fill a number in for X here.