Hello I have the following table design
ID account_id score date
------------------------------------------
1 500 4 x
2 764 4 x
3 500 6 x
4 500 7 x
5 764 5 x
I'm trying to get all rows with the latest account_id entry
so my code should return
ID account_id score date
------------------------------------------
4 500 7 x
5 764 5 x
I tried the following code but it seems to return the first entry but with the latest date
SELECT account_id,score, max(date) from table group by account_id
Case 1: If id is auto-increment column or max(id) means latest row.
select * from
(select * from table_name
order by id desc) temp
group by account_id
Case 2: If date column decides latest row then replace id by date in order clause and group clause.
try it-
SELECT distinct a.id,a.account_id,b.score,b.date
FROM mytable b
JOIN
(
SELECT account_id,MAX(id) AS id
FROM mytable
GROUP BY account_id
) a ON a.account_id=b.account_id
ORDER BY a.id;
This question is just a duplicate of SQL Select only rows with Max Value on a Column
There you'll find a good explanation.
SELECT a.*
FROM table a
INNER JOIN (
SELECT `account_id`,MAX(`date`) AS latest FROM table GROUP BY account_id
) b
ON a.`date` = b.`latest` AND a.`account_id` = b.`account_id`
ORDER BY `date` DESC
Reference :
Using ORDER BY and GROUP BY together
Try using this query it works fine
Select a.account_id,a.score,a.date
from authors as a
join
(Select account_id,max(date) as date
from authors
group by account_id) as d
on(d.date=a.date)
Related
I have the table:
id | date_submitted
1 | 01/01/2017
1 | 01/02/2017
2 | 01/03/2017
2 | 01/04/2017
I'm looking for the correct SQL to select each row, limited to one row per id that has the latest value in date_submitted.
So the SQL should return for the above table:
id | date_submitted
1 | 01/02/2017
2 | 01/04/2017
The query needs to select everything in the row, too.
Thanks for your help.
You can find max date for each id in subquery and join it with the original table to get all the rows with all the columns (assuming there are more columns apart from id and date_submitted) like this:
select t.*
from your_table t
inner join (
select id, max(date_submitted) date_submitted
from your_table
group by id
) t2 on t.id = t2.id
and t.date_submitted = t2.date_submitted;
Note that this query will return multiple rows for an id in case there are multiple rows with date_submitted equals to max date_submitted for that id. If you really want only one row per id, then the solution will be a bit different.
If you just need id and max date use:
select id, max(date_submitted) date_submitted
from your_table
group by id
I want to do the following. I have a table in the database, I am working on a table called asistencia and this table has 3 columns
id_asistencia as a int AUTOINCREMENT
nro_matricula as an int which I took it from another table called
alumnos
fecha as a date
This is a sketch of the database
id_asistencia | nro_matricula | fecha
1 | 0001| 2015-01-10
2 | 0002| 2015-01-10
3 | 0002| 2015-02-10 (another date )
The thing is I have to do a percentage
select all id_1 records in my nro_matricula column and see how many times its repeated in my rows and do a percentage respect all the dates in my database
EG : id_1 came to class day(whatever day) and he/she did not came to class the next day so id_1 has 50% assistance
Expected result
nro_matricula | percentage
0001| 50
0002| 100
The question is how can I make this query. If can be done in PHP its even better but i feel that this can be done in SQL
PS : The Database wasn't created by me
And excuse my English is not the better and i expect it to be understandable for you to help me
You can use sql statement like this:
select (
sum (if nro_matricula = '001' ,1,0 )
/ count(*)
from asistencia
--where nro_matricula = '001'
Maybe just simply:
select al.nro_matricula,
100 * count(distinct al.fecha) / (select count(distinct al1.fecha) from alumnos al1) as percentage
from alumnos al
group by al.nro_matricula
I did found the answer to my question. Thank you all for helping me out
SELECT
asistencia.nro_matricula as matricula,
COUNT( DISTINCT asistencia.fecha)* 100 /
COUNT( DISTINCT asistencia.nro_matricula) / (SELECT COUNT(DISTINCT asistencia.fecha)
FROM asistencia
ORDER BY COUNT(*) DESC
LIMIT 1 )
as porcentaje_asistencia
FROM asistencia
JOIN alumno
WHERE asistencia.nro_matricula = alumno.nro_matricula AND alumno.id_curso = 'basica6a'
Tried this in Oracle. Should work in MySQL too.
SELECT aa.NRO_MATRICULA , days_present/total_count* 100 FROM
(SELECT DISTINCT NRO_MATRICULA,
COUNT(*) as days_present FROM ASISTENCIA GROUP BY NRO_MATRICULA ) AA
,
(SELECT COUNT(*) as total_count FROM (SELECT DISTINCT(FECHA) FROM ASISTENCIA GROUP BY FECHA)) BB
Ouptut
nro_matricula percentage
0001 50
0002 100
The query (SELECT COUNT(*) FROM (SELECT DISTINCT(FECHA) FROM ASISTENCIA AA GROUP BY FECHA)) will give count of distinct date (2 in your case). Then we are getting distinct nro_matricula group by nro_matricula to get its count which will give the days it was present. Then divide both values from above steps to get percentage.
This is my table, I should fetch the MAX (id) of each status_id.
id status_id
10 1
11 1
12 2
13 2
14 2
15 4
16 4
So, I use this sql query, it works true and fetchs me all max ID.
select status_id, max(id) as max FROM `table`
where status_id in (1,2,3,4) group by status_id
This sql command fetchs me 3 MAX id using while.
11, 14, 16....
You see, there is not any suitable id to 3rd status_id. And if there is not any suitable id to 3rd status_id just mark it as zero. So I want that sql will bring these results:
11, 14, 0, 16
You can create a subquery which basically has all the ID's you need and have a left join against it.
SELECT a.status_ID,
IFNULL(MAX(b.id), 0) maxVal
FROM
(
SELECT 1 status_ID UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4
) a
LEFT JOIN `table` b ON a.status_id = b.status_id
GROUP BY a.status_id
SQLFiddle Demo
You can join with a temporary dummy table containing all ids and a stats_id value of 0:
SELECT dummy.status_id, COALESCE(MAX(id), 0) AS max
FROM (
SELECT 1 status_id
UNION SELECT 2 status_id
UNION SELECT 3 status_id
UNION SELECT 4 status_id
) dummy
LEFT JOIN `table`
ON dummy.status_id = table.status_id
GROUP BY dummy.status_id
But this does not scale and is a maintenance nightmare (you have to change the dummy-select in case a new status_id turns up). If you have a table containing ALL status_ids, replace the dummy-select with that table.
I have two table 'topic' and 'subcategory'
I am using this query--
Select * from `subcategory` as s
Inner join `topic` as f
WHERE s.`Subcategory_id` = f.`Subcategory_id
My result shows like
Category_id Subcategory_id Post_id time
2 2.3 4 2012-12-01
1 1.5 5 2013-01-20
1 1.3 6 2013-03-18
There's also other columns... but all I want is to select the latest Post_id and Subcategory_id of one Category_id ... that means here Category 1 has two Subcategory it will select only the latest(here 1.3) and same result all the time for all Category when database will grown larger. What will be the next query or how could I change the existing query to gain my desired result?
SELECT Post_Id, Subcategory_Id from subcategory as s, topic as t where
s.Subcategory_id = t.Subcategory_id and time = (
SELECT Max(time) from subcategory as s1, topic as t1 where
s1.Subcategory_id = t1.Subcategory_id and s1.Category_id = s.Category_id
);
Something like that, I think, will work.
SELECT TOP 1 ... ORDER BY whatever column determines "the latest"
e.g.
SELECT TOP 1 ... ORDER BY TIME DESCENDING
Or in case of mysql:
SELECT ... ORDER BY TIME DESCENDING LIMIT 1
Join your topic table with following query:
SELECT s.* FROM subcategory s
Inner JOIN (SELECT s1.Category_id,
MAX(s1.time1) AS max_time
FROM subcategory s1
GROUP BY s1.Category_id) y
ON y.Category_id = s.Category_id AND y.max_time = s.time1
I use mysql 5.1.
This is my DB schema :
id user_id type created_at
1 32 X 2012-11-19
2 32 Y 2012-11-18
3 30 X 2012-11-16
4 32 Z 2012-11-17
5 31 Y 2012-11-13
6 32 Z 2012-11-9
I want that my SQL query returns the user_id, type, and the lastest created_at for each type.
I tried to make this request:
SELECT max(type) FROM notification WHERE user_id=34 ORDER BY type but it returns only the latest created_at.
You cannot do this in really simple query because GROUP BY (which you are missing by the way in your query) doesn't guarantee that it won't return values mixed from multiple rows.
SELECT * FROM notifications AS t1
INNER JOIN (
SELECT type, MAX(`created_at`) AS max_created_at
FROM notification
WHERE user_id=34
GROUP BY `type`
) AS t2
ON t1.type = t2.type
AND t1.created_at = t2.max_created_at
select n.id, n.user_id, n.type, m.max_created_at
from notification n
inner join
(
select type, max(created_at) as max_created_at
from notification
group by type
) m on n.type = m.type and
m.max_created_at = n.created_at
Note this does assume that there are not two records with the same type and created_at date.
SELECT user_id, type, max(created_at) FROM notification WHERE user_id=34 GROUP BY user_id,type ORDER BY type
The following query selects the highest created_at for each type:
SELECT type, MAX(created_at) FROM notification GROUP BY type ORDER BY type
Not sure how you want to combine that with user, your question isn't precise enough.
The following query selects the highest created_at for each type for a specific user:
SELECT user, type, MAX(created_at)
FROM notification
WHERE user = 34
GROUP BY type, user
ORDER BY type, user
SELECT max(type) FROM notification WHERE user_id=34 ORDER BY type
try to revise like this
SELECT user_id, type,created_at FROM notification WHERE user_id=34 ORDER BY type
then if you want to see from latest to oldest or oldest to lastest
add ASC or DESC order