SELECT art.*,arg. FROM rd_articles AS art
LEFT JOIN rd_argument AS arg ON art.cat=arg.id WHERE art.enabled=1 ORDER BY art.id DESC
LIMIT 10
This is simple join query
Article table structure is
ID cat Description Date
1 1 Abc 08-01-2014
2 1 Aaa 10-01-2014
3 2 Abcv 11-01-2014
4 3 Aaa 12-01-2014
5 3 Aaa 14-01-2014
Arguments table is
ID Name
1 A
2 B
3 C
I want pick last updated(Date) one item from each cat.
How ?
This assumes that the enabled column is in rd_articles:
SELECT art.*, arg.*
FROM (
SELECT * FROM rd_articles
INNER JOIN (
SELECT cat, MAX(date) AS maxdate
FROM rd_articles
WHERE enabled = 1
GROUP BY cat
) md ON rd_articles.cat = md.cat AND rd_articles.date = md.maxdate
) art
LEFT JOIN rd_argument AS arg ON art.cat = arg.id
The innermost query gets the maximum date for each category, then joins it to the rd_articles table to get only those rd_articles rows that have the latest date for each article. That becomes the cat alias, which is then left-joined to the arguments table just like in your original query. You can add the LIMIT 10 at the end if needed; I wasn't sure what to do with that.
Note that if there's a tie for a category's latest date, you'll get more than one row for each category. If a tie could happen you'll need to break the tie somehow, for example by using the description or the ID. Let me know if that's the case and I'll update my answer.
SELECT ART.*, ARG.*
FROM ARTICLE AS ART
INNER JOIN RD_AGRUEMENT AS ARG
ON ARG.ID = ART.ID
WHERE (ID, DATE) IN
(SELECT ID, MAX(DATE) FROM ARTICLE GROUP BY ID)
Related
I need to make one SQL command.
From table with comments i'll get comment id, then
with this ID I need to get count of reactions with the same comment ID and user's names.
So for example I have this 2 tables:
Comments:
ID
Comm_text
1
Example text
2
Another example
and Reactions:
ID
comm_id
usr
etc..
1
1
Peter
another
2
1
John
collon
3
1
Dog
cuz
4
2
Cat
why not
I need to get this:
ID
Comm_text
Reactions_Count
Users
1
Example text
3
Peter, John, Dog
2
Another example
1
Cat
I tried this:
SELECT k.id, k.comm, COUNT(r.id) as reactions, r.usr
FROM `comms` k
INNER JOIN `reactions` r ON r.id=k.id
It's just one row with one comment and count of all rows in reaction table.
Thanks.
Try this query that makes the same output:
select comments.id as ID , comments.Comm_text as Comm_text ,
(select count(id) from Reactions where comm_id = comments.id) as Reactions_Count ,
(select coalesce(GROUP_CONCAT(usr ORDER BY usr DESC) , '') from Reactions WHERE comm_id = comments.id) as Users
from comments group by comments.id
You should use group by to group the comments and have just one row then use query to count and gather the data, based on each row of the group.
The GROUP_CONCAT attach the output with , and the coalesce set the output to a given string if the output was empty.
Read more about:
GROUP BY
GROUP_CONCAT
COALESCE
subquery
According to the names that u set in the example, this will work. Just fix the table names for your database structure.
SELECT `Comments`.`ID`, `Comments`.`Comm_text`, count(`Reactions`.`comm_id`) as react, `Reactions`.`usr`
FROM `Comments`
INNER JOIN `Reactions`
ON `Comments`.`ID`=`Reactions`.`comm_id`
GROUP BY `Reactions`.`comm_id`
How can I select the ID of a row with the max value of another column in a query that joins multiple tables?
For example, say I have three tables. tblAccount which stores a grouping of users, like a family. tblUser which stores the users, each tied to a record from tblAccount. And each user can be part of a plan, stored in tblPlans. Each plan has a Rank column that determines it's sorting when comparing the levels of plans. For example, Lite is lower than Premium. So the idea is that each user can have a separate plan, like Premium, Basic, Lite etc..., but the parent account does not have a plan.
How can I determine the highest plan in the account with a single query?
tblAccount
PKID
Name
1
Adams Family
2
Cool Family
tblUsers
PKID
Name
AccountID
PlanID
1
Bob
1
3
2
Phil
2
2
3
Suzie
2
1
tblPlans
PKID
Name
Rank
1
Premium
3
2
Basic
2
3
Elite
4
4
Lite
1
Here's the result I'm hoping to produce:
AccountID
Name
HighestPlanID
PlanName
2
Adams Family
1
Premium
I've tried:
SELECT U.AccountID, A.Name, MAX(P.Rank) AS Rank, P.PKID as HighestPlanID, P.Name as PlanName
FROM tblPlans P
INNER JOIN tblUsers U ON U.PlanID = P.PKID
INNER JOIN tblAccounts A ON U.AccountID = A.PKID
WHERE U.AccountID = 2
and the query will not always work, selecting the MAX of Rank does not select entire row's values from tblPlans.
I am looking for a solution that is compatible with mysql-5.6.10
You can join the tables and use ROW_NUMBER() to identify the row you want. Then filtering is ieasy.
For example:
select *
from (
select a.*, p.*,
row_number() over(partition by a.pkid order by p.rank desc) as rn
from tblaccount a
join tblusers u on u.accountid = a.pkid
join tblplans p on p.pkid = u.planid
) x
where rn = 1
Inside the subquery you can add where u.accountid = 2 to retrieve a single account of interest, instead of all of them.
With the help of #the-impaler, I massaged their answer a bit and came out with something very similar:
select *
from (
select a.*, p.*
from tblaccount a
join tblusers u on u.accountid = a.pkid
join tblplans p on p.pkid = u.planid
where u.accountid = 2
order by p.rank desc
) x limit 1
The subquery sorts each user by plan rank from top to bottom, and then the top level query selects the top most row with limit 1. It seems to work!
I have two tables songs and song_clubs. The schema is below:-
songs schema
id available_for song_name status
1 all Song 1 1
2 selection Song 2 1
3 selection Song 3 1
song_clubs schema
song_id club_id
2 1
2 2
3 2
Now i want to fetch the songs of club id 1 and the song is available for all clubs.
My execpted output is like below:-
id available_for song_name
1 all Song 1
2 selection Song 2
I have tried below Query
select id,available_for,song_name from songs
JOIN
song_clubs
on song_clubs.song_id = songs.id
WHERE songs.status =1 and song_clubs.club_id=1 or songs.available_for ='all'
But its only returning one entry that is selection based.
You can do it with EXISTS:
SELECT s.id, s.available_for, s.song_name
FROM songs s
WHERE s.status =1 AND (
s.available_for = 'all'
OR EXISTS (SELECT 1 FROM song_clubs c WHERE c.club_id = 1 AND c.song_id = s.id))
or with the operator IN:
SELECT id, available_for, song_name
FROM songs
WHERE status =1 AND (
available_for = 'all'
OR id IN (SELECT song_id FROM song_clubs WHERE club_id = 1))
Two things.
Use parentheses to group WHERE clauses; otherwise they evaluate left-to-right.
Use LEFT JOIN to avoid losing items from your first table that don't match any items in your second table.
This should work (https://www.db-fiddle.com/f/6dAz91ejhe8AbGECFDihbu/0)
SELECT id,available_for,song_name
FROM songs
LEFT JOIN song_clubs ON songs.id = song_clubs.song_id
WHERE songs.status = 1
AND (song_clubs.club_id=1 or songs.available_for ='all')
ORDER BY id;
you can use this answer too
select unique id,available_for,song from songs,song_clubs
WHERE (song_clubs.song_id = songs.id and songs.status = 1 and song_clubs.club_id=1) or (songs.available_for ='all');
Here I use full join to select all the matches and then select the unique id values for the songs so you can get only the required 2 rows
Note: It is not the best performance query if you have huge tables.
and it is better to use EXISTS or LEFT JOIN.so other answers are more better for performance and this answer is just another way to do that.
I have a couple tables in MySQL DB
EID Name
1 Title A
2 Title B
3 Title C
LID EID Location Address Order
1 1 Office NY 1
2 1 Home IL 2
3 2 Office CA 1
4 3 Home NJ 2
I have the above 2 tables (Employee and Location). I would like to know the location of each Employee with office as a preferred choice and if 'office' does not exist then would need 'Home' location . The order column defined the order/priority of what is needed.
here is the output needed
EID LID Name Location Address
1 1 Title A Office NY
2 3 Title B Office CA
3 4 Title C Home NJ
The first join of the query below just connects the Employee and Location tables, but note that it results in all records from Location being joined. The critical part of the below query is the second INNER JOIN to a subquery. This subquery identifies the minimum (i.e. highest priority) order for each employee ID. This is then used to discard records from the first join which are not the highest priority.
SELECT t1.EID,
t2.LID,
t1.Name,
t2.Location,
t2.Address
FROM Employee t1
INNER JOIN Location t2
ON t1.EID = t2.EID
INNER JOIN
(
SELECT EID, MIN(`Order`) AS min_order
FROM Location
GROUP BY EID
) t3
ON t2.EID = t3.EID AND
t2.Order = t3.min_order
One other note: Don't name your columns Order, which is a MySQL keyword. To get my query to work, I had to put it in backticks, which is inconvenient to say the least, and possibly error prone.
Demo here:
SQLFiddle
There are two posibility to get your result.
1)If you need Based on Order result then use this query
SELECT e1.EID, l1.LID, e1.Name, l1.Location, l1.Address
FROM Employee e1
JOIN
(SELECT MIN(`Order `) as Minorder, EID, LID, Location, Address, Order
FROM Location l1
GROUP BY EID) l1
ON l1.EID = e1.EID AND l1.Minorder = l1.Order;
2)if you need result Based on EID then use this query
SELECT e1.EID,l1.LID,e1.Name,l1.Location,l1.Address
FROM Employee e1 JOIN
(SELECT MIN(`EID`)as Mineid,EID,LID,Location,Address,`Order` FROM Location l1 GROUP BY EID)l1
ON l1.Mineid = e1.EID;
Extra Note:-
Plese donot use mysql inbuilt keyword as Column name or Table name for more information read this link click here
You can the expected result by using inner join
Select a.eid,b.Lid,a.name,b.location,b.address from Table1 a innner join (select * from Tableb group by eid) b on
a.eid=b.eid;
you can try this code this will help you as i think
select E.EID,E.name,ad.LID,ad.LOCATION,ad.ADDRESS,ad.[order]
from #emp E inner join #address ad on E.EID = ad.EID
inner join (select EID, min([order]) [order]
from #address
group by EID) tt on ad.EID = tt.EIDand ad.[order] = tt.[order]
Using the tables below as an example and the listed query as a base query, I want to add a way to select only rows with a max id! Without having to do a second query!
TABLE VEHICLES
id vehicleName
----- --------
1 cool car
2 cool car
3 cool bus
4 cool bus
5 cool bus
6 car
7 truck
8 motorcycle
9 scooter
10 scooter
11 bus
TABLE VEHICLE NAMES
nameId vehicleName
------ -------
1 cool car
2 cool bus
3 car
4 truck
5 motorcycle
6 scooter
7 bus
TABLE VEHICLE ATTRIBUTES
nameId attribute
------ ---------
1 FAST
1 SMALL
1 SHINY
2 BIG
2 SLOW
3 EXPENSIVE
4 SHINY
5 FAST
5 SMALL
6 SHINY
6 SMALL
7 SMALL
And the base query:
select a.*
from vehicle a
join vehicle_names b using(vehicleName)
join vehicle_attribs c using(nameId)
where c.attribute in('SMALL', 'SHINY')
and a.vehicleName like '%coo%'
group
by a.id
having count(distinct c.attribute) = 2;
So what I want to achieve is to select rows with certain attributes, that match a name but only one entry for each name that matches where the id is the highest!
So a working solution in this example would return the below rows:
id vehicleName
----- --------
2 cool car
10 scooter
if it was using some sort of max on the id
at the moment I get all the entries for cool car and scooter.
My real world database follows a similar structure and has 10's of thousands of entries in it so a query like above could easily return 3000+ results. I limit the results to 100 rows to keep execution time low as the results are used in a search on my site. The reason I have repeats of "vehicles" with the same name but only a different ID is that new models are constantly added but I keep the older one around for those that want to dig them up! But on a search by car name I don't want to return the older cards just the newest one which is the one with the highest ID!
The correct answer would adapt the query I provided above that I'm currently using and have it only return rows where the name matches but has the highest id!
If this isn't possible, suggestions on how I can achieve what I want without massively increasing the execution time of a search would be appreciated!
If you want to keep your logic, here what I would do:
select a.*
from vehicle a
left join vehicle a2 on (a.vehicleName = a2.vehicleName and a.id < a2.id)
join vehicle_names b on (a.vehicleName = b.vehicleName)
join vehicle_attribs c using(nameId)
where c.attribute in('SMALL', 'SHINY')
and a.vehicleName like '%coo%'
and a2.id is null
group by a.id
having count(distinct c.attribute) = 2;
Which yield:
+----+-------------+
| id | vehicleName |
+----+-------------+
| 2 | cool car |
| 10 | scooter |
+----+-------------+
2 rows in set (0.00 sec)
As other said, normalization could be done on few levels:
Keeping your current vehicle_names table as the primary lookup table, I would change:
update vehicle a
inner join vehicle_names b using (vehicleName)
set a.vehicleName = b.nameId;
alter table vehicle change column vehicleName nameId int;
create table attribs (
attribId int auto_increment primary key,
attribute varchar(20),
unique key attribute (attribute)
);
insert into attribs (attribute)
select distinct attribute from vehicle_attribs;
update vehicle_attribs a
inner join attribs b using (attribute)
set a.attribute=b.attribId;
alter table vehicle_attribs change column attribute attribId int;
Which led to the following query:
select a.id, b.vehicleName
from vehicle a
left join vehicle a2 on (a.nameId = a2.nameId and a.id < a2.id)
join vehicle_names b on (a.nameId = b.nameId)
join vehicle_attribs c on (a.nameId=c.nameId)
inner join attribs d using (attribId)
where d.attribute in ('SMALL', 'SHINY')
and b.vehicleName like '%coo%'
and a2.id is null
group by a.id
having count(distinct d.attribute) = 2;
The table does not seems normalized, however this facilitate you to do this :
select max(id), vehicleName
from VEHICLES
group by vehicleName
having count(*)>=2;
I'm not sure I completely understand your model, but the following query satisfies your requirements as they stand. The first sub query finds the latest version of the vehicle. The second query satisfies your "and" condition. Then I just join the queries on vehiclename (which is the key?).
select a.id
,a.vehiclename
from (select a.vehicleName, max(id) as id
from vehicle a
where vehicleName like '%coo%'
group by vehicleName
) as a
join (select b.vehiclename
from vehicle_names b
join vehicle_attribs c using(nameId)
where c.attribute in('SMALL', 'SHINY')
group by b.vehiclename
having count(distinct c.attribute) = 2
) as b on (a.vehicleName = b.vehicleName);
If this "latest vehicle" logic is something you will need to do a lot, a small suggestion would be to create a view (see below) which returns the latest version of each vehicle. Then you could use the view instead of the find-max-query. Note that this is purely for ease-of-use, it offers no performance benefits.
select *
from vehicle a
where id = (select max(b.id)
from vehicle b
where a.vehiclename = b.vehiclename);
Without going into proper redesign of you model you could
1) Add a column IsLatest that your application could manage.
This is not perfect but will satisfy you question (until next problem, see not at the end)
All you need is when you add a new entry to issue queries such as
UPDATE a
SET IsLatest = 0
WHERE IsLatest = 1
INSERT new a
UPDATE a
SET IsLatest = 1
WHERE nameId = #last_inserted_id
in a transaction or a trigger
2) Alternatively you can find out the max_id before you issue your query
SELECT MAX(nameId)
FROM a
WHERE vehicleName = #name
3) You can do it in single SQL, and providing indexes on (vehicleName, nameId) it should actually have decent speed with
select a.*
from vehicle a
join vehicle_names b ON a.vehicleName = b.vehicleName
join vehicle_attribs c ON b.nameId = c.nameId AND c.attribute = 'SMALL'
join vehicle_attribs d ON b.nameId = c.nameId AND d.attribute = 'SHINY'
join vehicle notmax ON a.vehicleName = b.vehicleName AND a.nameid < notmax.nameid
where a.vehicleName like '%coo%'
AND notmax.id IS NULL
I have removed your GROUP BY and HAVING and replaced it with another join (assuming that only single attribute per nameId is possible).
I have also used one of the ways to find max per group and that is to join a table on itself and filter out a row for which there are no records that have a bigger id for a same name.
There are other ways, search so for 'max per group sql'. Also see here, though not complete.