Does anyone know how to find ranges that overlap, using MySQL? Essentially, as seen on table below (just for illustrating the problem as the actual table contains 1000+ ranges), I am trying to fetch all ranges that overlap inside of a table.
Thanks!
RANGES
| count | Begin | End | Comment |
| 1 | 1001 | 1095 | overlaps with ranges 2, 3 |
| 2 | 1005 | 1030 | overlaps with ranges 1, 3 |
| 3 | 1017 | 1020 | overlaps with ranges 1, 2 |
| 4 | 1110 | 1125 | no overlap |
One method is a self join and aggregation:
select r1.count, r1.begin, r1.end,
group_concat(r2.count order by r2.count) as overlaps
from ranges r1 left join
ranges r2
on r1.end >= r2.begin and
r1.begin <= r2.end and
r1.count <> r2.count
group by r1.count, r1.begin, r1.end;
On a table with 1000 rows, this will not be fast, but it should be doable. You may want to validate the logic on a smaller table.
This assumes that count is really a unique identifier for each row.
Note that count and end are poor choices for column names because they are SQL keywords.
Here is a db<>fiddle.
Related
i am trying to fine tune a query which runs on application dashboard.
Query is like i have a master table & few transaction tables. I have to make some calculation on transataion table & showcase same output along with few columns from the master table.
I tried with join that worked but query is not fast enough for application ( 40Sec for 1k Records).
I am trying with sub query but maybe i am making mistake somewhere.
sharing dummy details below.
Master table :
id
name
1
Cell1
2
Cell2
3
Cell3
4
Cell4
transaction table 1 Session1
| id | TotalMarks |
| 1 | 21 |
| 1 | 21 |
| 2 | 23 |
| 3 | 24 |
Transaction table 2 Session2
| id | TotalMarks |
| 1 | 22 |
| 2 | 28 |
| 4 | 25 |
| 4 | 29 |
Result i want Like
| id | Name | ObtainMarksSession1 | totalObtainMarkSession2 |
| 1 | cell1 |
| |
I have checked indexes already but anyway index won't help as i am using aggregate function.
join query
Select m.id,m.name,sum(s1.TotalMarks) ObtainMarksSession1, sum(s1.TotalMarks) ObtainMarksSession2
from master join session1 s1 on m.id=s1.id and s1.id is not null
join session2 s2 on m.id=s2.id and s2.id is not null
group by m.id,m.name;
subquery Sample
Select id, sum(TotalMarks) ObtainMarksSession1 from session1 where id is not null;
Same way i got result from other table also but now i am unable to merge both output. these single query output are very fast.
Need to know how to merge result & get output with name as well from master. also, other suggestion if i can try some other method to make this query fast.
P.s Id is not primary key in transaction table so there might be possiblity for null values.
i need to return the best 5 scores in each category from a table.so far i have tried query below following an example from this site: selecting top n records per group
query:
select
subject_name,substring_index(substring_index
(group_concat(exams_scores.admission_no order by exams_scores.score desc),',',value),',',-1) as names,
substring_index(substring_index(group_concat(score order by score desc),',',value),',',-1)
as orderedscore
from exams_scores,students,subjects,tinyint_asc
where tinyint_asc.value >=1 and tinyint_asc.value <=5 and exam_id=2
and exams_scores.admission_no=students.admission_no and students.form_id=1 and
exams_scores.subject_code=subjects.subject_code group by exams_scores.subject_code,value;
i get the top n as i need but my problem is that its returning duplicates at random which i dont know where they are coming from
As you can see English and Math have duplicates which should not be there
+------------------+-------+--------------+
| subject_name | names | orderedscore |
+------------------+-------+--------------+
| English | 1500 | 100 |
| English | 1500 | 100 |
| English | 2491 | 100 |
| English | 1501 | 99 |
| English | 1111 | 99 |
|Mathematics | 1004 | 100 |
| Mathematics | 1004 | 100 |
| Mathematics | 2722 | 99 |
| Mathematics | 2734 | 99 |
| Mathematics | 2712 | 99 |
+-----------------------------------------+
I have checked table and no duplicates exist
to confirm there are no duplicates in the table:
select * from exams_scores
having(exam_id=2) and (subject_code=121) and (admission_no=1004);
result :
+------+--------------+---------+--------------+-------+
| id | admission_no | exam_id | subject_code | score |
+------+--------------+---------+--------------+-------+
| 4919 | 1004 | 2 | 121 | 100 |
+------+--------------+---------+--------------+-------+
1 row in set (0.00 sec)
same result for English.
If i run the query like 5 times i sometimes end up with another field having duplicate values.
can anyone tell me why my query is behaving this way..i tried adding distinct inside
group_concat(ditinct(exams_scores.admission_no))
but that didnt work ??
You're grouping by exams_scores.subject_code, value. If you add them to your selected columns (...as orderedscore, exams_scores.subject_code, value from...), you should see that all rows are distinct with respect to these two columns you grouped by. Which is the correct semantics of GROUP BY.
Edit, to clarify:
First, the SQL server removes some rows according to your WHERE clause.
Afterwards, it groups the remaining rows according to your GROUP BY clause.
Finally, it selects the colums you specified, either by directly returning a column's value or performing a GROUP_CONCAT on some of the columns and returning their accumulated value.
If you select columns not included in the GROUP BY clause, the returned results for these columns are arbitrary, since the SQL server reduces all rows equal with respect to the columns specified in the GROUP BY clause to one single row - as for the remaining columns, the results are pretty much undefined (hence the "randomness" you're experiencing), because - what should the server choose as a value for this column? It can only pick one randomly from all the reduced rows.
In fact, some SQL servers won't perform such a query and return an SQL error, since the result for those columns would be undefined, which is something you don't want to have in general. With these servers (I believe MSSQL is one of them), you more or less can only have columns in you SELECT clause which are part of your GROUP BY clause.
Edit 2: Which, finally, means that you have to refine your GROUP BY clause to obtain the grouping that you want.
Thanks for taking a look at this question. I'm kind of lost and hope someone can help me. Below is a update query i would like to run.
This query now returns an error:
1054 - Unknown column 'spi.et_cross_rank' in 'where clause'
Some background:
from table: tmp_ranking_tbl
I would like to get the nth(spi.et_return_rank) record
for a group with value x (spi.et_cross_rank)
SET #rownum=0;
UPDATE STRToer_Poule_indeling spi
SET spi.team_id = (SELECT R.team_poule_id
FROM (SELECT #rownum:=#rownum+1 AS rownum, trt.team_poule_id
FROM tmp_ranking_tbl trt
WHERE trt.overal_rank = spi.et_cross_rank
ORDER BY trt.punten DESC, (trt.goals_voor - trt.goals_tegen) DESC, trt.goals_voor DESC) R
WHERE R.rownum = spi.et_return_rank)
WHERE spi.et_ronde = v_et_ronde
AND spi.poule_id IN (SELECT row_id FROM STRToer_Poules WHERE toernooi_onderdeel_id=v_onderdeel_id) ;
Data in tmp_ranking_tbl looks like:
team_poule_id | punten | goals_voor | goals_tegen | overal_rank
65 | 6 | 10 | 10 | 2
69 | 6 | 9 | 10 | 2
75 | 7 | 11 | 4 | 2
84 | 6 | 6 | 8 | 2
112 | 5 | 7 | 7 | 2
Thanks in advance for the help!
Update after question in comment about the goal, i'll try to keep it short. :-)
This query is used on a website to keep scores of a tournament. Sometimes you have an odd number of teams going to the next round. At that point I want to select the best number 3(spi.et_cross_rank) team across poules. This is setting saved in the STRToer_Poule_indeling with what rank per poule and the 1st, 2nd or nth team(spi.et_return_rank). The table tmp_ranking_tbl is filled with all rank 3 teams across the poules. When this if filled I would like the 1st or 2nd, depedining on the setting in STRToer_Poule_indeling, record to return.
Subset of structure the STRToer_Poule_indeling table
row_id | team_id | et_ronde | et_cross_rank | et_return_rank
1 | null | 1 | 3 | 1
Just check if you have a column named et_cross_rank on your table STRToer_Poule_indeling
The problem seems to be that SQL can't find that column on your table.
Hope it helps.
I need to store a set of numbers in a MySQL database. I need some help to determine the best table structure to use.
There are 20 numbers that will be stored in each row, along with an ID. The numbers can range from 1 - 80 and there are no repeats in this series of numbers.
Initially I created a table structure with 21 columns, an ID and 20 columns that store each individual number.
Id | Num1 | Num2 | Num3 | Num4 | Num5 | etc.. |
----------------------------------------------------------
0001 | 1 | 4 | 15 | 22 | 39 | 43 |
0002 | 3 | 5 | 22 | 43 | 55 | 58 |
0003 | 1 | 3 | 5 | 6 | 15 | 26 |
I've also thought of a table with 81 columns, an ID and 80 boolean columns that would represent each individual number.
Id | 1 | 2 | 3 | 4 | 5 | etc.. |
----------------------------------------------------------
0001 | True | False | False | True | True | False |
0002 | False | False | True | False | True | False |
0003 | True | False | True | False | True | True |
Can anyone give some advice to the pros and cons of each table structure, and which would be easier to use when searching this table.
For example, we would need to search for every row that contains 1,2,5,66, and 79.
Or every row that contains 16,33, and 4.
Any guidence would be appreciated.
What you're looking for is called database normalization; a way to organize data that prevents duplication and anomalies (like changing one record inadvertently changing another record).
Higher-normal forms depend on the meaning of your data, which you have not told us, but to start you should avoid ordered or indeterminate columns (like Num1, Num2, ...) and split your columns into rows:
ID Num
0001 1
0001 4
0001 15
...
0002 3
0002 5
...
In general, any time you find yourself adding a bunch of columns that depend on their position you are making a mistake. SQL has many functions for aggregating, combining, sorting, and reporting on rows. Use the features of SQL to produce the results you want; don't try to make your database schema look like the final printed report.
In answer to your comment, a query that returns only IDs that have Nums 1, 4, and 15, and no other ID:
select ID from YourTable
where Num in (1, 4, 15)
group by ID
having Count(ID) = 3
If Nums can be duplicated you will want something like having count(distinct ID). If you can have different counts of Nums to match you will have to create a temporary table of Nums to match and use having count(ID) = (select Count(Num) from TemporaryTable).
Note that SQL Server already has a master..spt_values table of integers to use in such situations; I do not know if MySql has such a thing, but they are easy to generate if you need one.
I have a query which currently should only display one row. However it somehow is displaying 4 rows as its result set even though 1) there are only three rows in the table to begin with 2) only one row matches the query criteria.
I am hoping someone might know what I am doing wrong with this MySql query
My database table structure is as below
smsid (int, auto increment), sms_type (text), sms_status (enum 'pending',sent'),
sms_error (test), sms_message(text), sms_mp3file (varchar 50),
sms_sendon (datetime), send_sms_toid (int 5)
My table entries are as so (following the order of the table columns above)
31 | mp3 | pending | | | helloworld.mp3 | 2013-11-20 16:16:00 | 7
30 | text | sent | | hello test | | 2013-11-18 13:12:00 | 8
29 | voice | sent | | testing 123 | | 2013-11-18 10:05:00 | 18
My query is as below
SELECT sms_messages.*, sms_recipients.cust_profid, sms_recipients.sms_cellnumber,
customer_smsnumbers.sms_number, customer_smsnumbers.sms_number
FROM sms_messages, sms_recipients, customer_smsnumbers
WHERE sms_messages.sms_type='mp3' AND sms_messages.sms_sendon <= '2013-11-21'
AND sms_messages.sms_status='pending' AND
sms_messages.send_sms_toid = sms_recipients.smsuser_id
In your query, you have missed a JOINING clause for customer_smsnumbers table. Similar to sms_messages.send_sms_toid = sms_recipients.smsuser_id you need to have a join clause which either connects sms_messages with customer_smsnumbers table or connects sms_recipients with the customer_smsnumbers table.
In the absence of a join clause other (unintended) records are included in the result.