I have a simple MySQL table:
| id | sid | date |
+--------+---------+------------+
| 1 | 1 | 2013-12-01 |
+--------+---------+------------+
| 3 | 2 | 2013-12-17 |
+--------+---------+------------+
| 4 | 1 | 2013-12-17 |
+--------+---------+------------+
| 5 | 1 | 2013-12-18 |
+--------+---------+------------+
I need group this table by sid field and get records with max id for each sid with correct date. I try below code:
SELECT MAX(id), date FROM my_table GROUP BY sid
But the date field is incorrect, for example I get date 2013-12-01 with id 5 as a result.
What am I doing wrong ?
The way standard SQL is defined (at least up to ansi 1992, others will correct me), any field of your SELECT clause must be included in your group by condition. [Mysql allows you to not do so, but that is why it is confusing: the results are not as you expect]
Your query should then be:
SELECT MAX(id), date FROM my_table GROUP BY sid, date
But in this case, clearly this is not what you want. Your requirement is to get the date corresponding to the MAX(id) for each sId.
You have to isolate each part of the algorithm in different queries.
1 - get the max id for each sid:
SELECT MAX(id) AS id, sid FROM my_table GROUP BY sid
2 - get the date corresponding to the max of ids for each sid:
SELECT date FROM my_table WHERE sid = X AND id = Y
3 - join these 2 queries using an INNER JOIN or more shortly, a JOIN:
SELECT m.sid, m.id, m.date
FROM my_table m
JOIN (SELECT MAX(id) AS id, sid FROM my_table GROUP BY sid) t
ON t.sid = m.sid AND m.id = t.id
You need a join:
SELECT a.id, a.date
FROM foo a
INNER JOIN (SELECT MAX(id) as max_id FROM foo GROUP BY sid) b ON a.id = b.max_id
Related
My table:
id | request | subject | date
1 | 5 | 1 | 576677
2 | 2 | 3 | 576698
3 | 5 | 1 | 576999
4 | 2 | 3 | 586999
5 | 2 | 7 | 596999
Need to select unique records by two columns(request,subject). But if we have different pairs of request-subject(2-3, 2-7), this records should be excluded from resulted query.
My query now is:
SELECT MAX(id), id, request, subject, date
FROM `tbl`
GROUP BY request, subject
having count(request) > 1
order by MAX(id) desc
How to exclude record with id=4, id=5 from this query? Thanks!
You may group by request, and then check for every group if all subjects in it are equal. You could do it using MIN() and MAX():
SELECT request, MIN(subject) AS subject
FROM table_1
GROUP BY request
HAVING MIN(subject) = MAX(subject)
As for your update, I assume you want all the fields for the max ID in the group (in your example, ID 3). The query would then look like this one:
SELECT *
FROM table_1 t
WHERE t.id IN (SELECT MAX(s.id)
FROM table_1 s
GROUP BY s.request
HAVING MIN(s.subject) = MAX(s.subject))
ORDER BY t.id
You can try this.
select * from MyTable T1
WHERE NOT EXISTS( SELECT * FROM MyTable T2
WHERE T1.id <> T2.id
and T1.request = T2.request
and T1.subject <> T2.subject)
Sql Fiddle
Table: purchase_history having all details of users
Fields are : id,uid, purchase_date, item_id, item_size, item_color
where id is a primary key.
There are many rows for an similar uid. e.g.
id | uid | purchase_date | item_id | item_size | item_color
1 | 200 | 2016-10-22 | 1021 | 3 | red
2 | 122 | 2016-08-02 | 21 | 1 | black
3 | 200 | 2016-05-01 | 222 | 1 | blue
4 | 101 | 2016-01-07 | 102 | 1 | red
So now I want a single query to get the last transaction date, item_id and uid group by uid. I used below query:
select uid, max(purchase_date), item_id from purchase_history group by uid;
it gives me correct uid and purchase date but the item id is not picked from the last row. It is coming from the first row. Is there any way that we can find the item id from the last row with uid and purchase_date?
Try this:
select uid, max(purchase_date) as date, item_id from purchase_history group by uid ORDER by date desc,item_id desc
Make sure that you item_id type is an integer.
You can find max of purchase date for each user in a subquery and join it with the main table like so:
select t1.uid, t1.purchase_date, t1.item_id
from purchase_history t1
inner join (
select uid, max(purchase_date) purchase_date
from purchase_history
group by uid
) t2 on t1.uid = t2.uid
and t1.purchase_date = t2.purchase_date;
NOTE: It'll give multiple rows for a uid, if there are rows with multiple max dates.
Use correlated subquery:
SELECT uid, purchase_date, item_id
FROM purchase_history p1
WHERE purchase_date = (
SELECT MAX(purchase_date)
FROM purchase_history p2
WHERE p2.uid = p1.uid
);
try this query
select * from (select * from purchase_history order by purchase_date asc) purchase_history group by uid;
Given a table such as the following called form_letters:
+---------------+----+
| respondent_id | id |
+---------------+----+
| 3 | 1 |
| 7 | 2 |
| 7 | 3 |
+---------------+----+
How can I select each of these rows except the ones that do not have the maximum id value for a given respondent_id.
Example results:
+---------------+----+
| respondent_id | id |
+---------------+----+
| 3 | 1 |
| 7 | 3 |
+---------------+----+
Something like this should work;
SELECT respondent_id, MAX(id) as id FROM form_letters
group by respondent_id
MySQL fiddle:
http://sqlfiddle.com/#!2/5c4dc0/2
There are many ways of doing it. group by using max(), or using not exits and using left join
Here is using left join which is better in terms of performance on indexed columns
select
f1.*
from form_letters f1
left join form_letters f2 on f1.respondent_id = f2.respondent_id
and f1.id < f2.id
where f2.respondent_id is null
Using not exits
select f1.*
from form_letters f1
where not exists
(
select 1 from form_letters f2
where f1.respondent_id = f2.respondent_id
and f1.id < f2.id
)
Demo
Here's how I would do it. Get the max id in a sub query, then join it back to your original table. Next, limit to records where the ID does not equal the max id.
Edit: Opposite of this. limit to records where the ID = MaxID. Code changed below.
Select FL.Respondent_ID, FL.ID, A.Max_ID
From Form_Letters FL
left join (
select Respondent_ID, Max(ID) as Max_ID
from Form_Letters
group by Respondent_ID) A
on FL.Respondent_ID = A.Respondent_ID
where FL.ID = A.Max_ID
I have a table of the following structure:
ID | COMPANY_ID | VERSION | TEXT
---------------------------------
1 | 1 | 1 | hello
2 | 1 | 2 | world
3 | 2 | 1 | foo
is there a way to get the most recent version of records only, i.e. I would want to have as a result set the IDs 2 and 3?
I'm sure there are better ways, but I tend to use this kind of query:
SELECT *
FROM
(SELECT * FROM test ORDER BY VERSION DESC) AS my_table
GROUP BY COMPANY_ID
Produces this result set:
ID | COMPANY_ID | VERSION | TEXT
---------------------------------
2 | 1 | 2 | world
3 | 2 | 1 | foo
Try this:
SELECT *
FROM (
SELECT company_id, MAX(version) maxVersion
FROM table
GROUP BY company_id ) as val
JOIN table t ON (val.company_id = t.company_id AND t.version = val.maxversion)
If your IDs are ordered (newer version iff higher id):
SELECT t.*, a.maxversion
FROM (
SELECT MAX(id) maxid, MAX(version) maxversion
FROM table
GROUP BY company_id
) a
INNER JOIN table t
ON a.maxid = t.id
However, if your IDs are not properly ordered, you need to use the following query:
SELECT t.*
FROM (
SELECT company_id, MAX(version) maxversion
FROM table
GROUP BY company_id
) v
INNER JOIN table t
ON v.company_id = t.company_id
AND v.maxversion = t.version
(assuming there's an UNIQUE constraint/index on (company_id, version))
i have table structure like this
sn | person_id | image_name |
1 | 1 | abc1.jpb
2 | 1 | aa11.jpg
3 | 11 | dsv.jpg
4 | 11 | dssd.jpg
5 | 11 | sdf.jpg
I need distinct person_id newest row as following
2 | 1 | aa11.jjpb
5 | 11 | sdf.jpg
IT is possible ?
SELECT * FROM yourtable GROUP BY person_id ORDER BY sn DESC
Essentially you want to select all records from your table. Then it is grouped by the person_id (limiting the result to 1 per person id)... Ordering by SN decending means that it will return the most recent (highest) sn
Update: (and verified)
SELECT * FROM (SELECT * FROM stackoverflow ORDER BY sn DESC) a GROUP BY person_id ORDER BY sn
SELECT * FROM table GROUP BY person_id HAVING MAX(sn)
EDIT
SELECT f.*
FROM (
SELECT person_id, MAX(sn) as maxval
FROM table GROUP BY person_id
) AS x INNER JOIN table AS f
ON f.person_id = x.person_id AND f.sn = x.maxval;
where table is your table name.
SELECT * FROM table a WHERE a.`id` = ( SELECT MAX(`id`) FROM table b WHERE b.`person_id` = a.`person_id` );
What you are doing inside the parenthesis is selecting the max id for the rows that have that distinct person_id. So for each unique person_id you are getting the most recent entry.