I am having an issue with my multi join SQL statement, where I need to get the last entries of the table and not the first. I have 3 tables that I try to query based on this statement:
SELECT DISTINCT i.id,i.hz,i.v,i.t,i.u,i.temp, i.c1, s.server, s.hostname, h.codes,s.cpus FROM `dc_servers` AS s INNER JOIN `dc_hardware` AS h ON s.server = h.server INNER JOIN `dc_systemusage` AS i ON s.server = i.server GROUP BY i.server
The tables dc_servers & dc_hardware only has 1 row per server, however the table dc_systemusage has many rows with the same server, as new info is being added.
When I run the query, I get the first entries from the dc_systemusage, but I need to get the latest entries from that table, for me it sounds like I need an ORDER BY, however if I add that to the end of the query like this:
SELECT DISTINCT i.id,i.hz,i.v,i.t,i.u,i.temp, i.c1, s.server, s.hostname, h.codes,s.cpus FROM `dc_servers` AS s INNER JOIN `dc_hardware` AS h ON s.server = h.server INNER JOIN `dc_systemusage` AS i ON s.server = i.server GROUP BY i.server ORDER BY i.id DESC
then I am just ordering the result, which is not what I am looking for.
I hope someone can guide me in the right direction as for how I can get the latest rows and not the first from the table dc_systemusage
I hope I have provided the needed information to guide me, else please do let me know and I will add whatever is neeeded.
Thank you all.
You can find dc_systemusage lastest ids in subquery and use with WHERE ... IN
SELECT i.id,i.hz,i.v,i.t,i.u,i.temp, i.c1, s.server, s.hostname, h.codes,s.cpus
FROM `dc_servers` AS s
INNER JOIN `dc_hardware` AS h ON s.server = h.server
INNER JOIN `dc_systemusage` AS i ON s.server = i.server
WHERE i.id IN (SELECT max(dc_systemusage.id) FROM dc_systemusage GROUP BY dc_systemusage.server)
and check a great answer at https://stackoverflow.com/a/3800572/7174186
Related
I have the rather lengthy SQL query that I have included below. As you can see it orders by AvgRating and NumReviews, both of which rely on data from the reviews table. Unfortunately I need to see the rows in my results even when there are no reviews, currently if there are no reviews to order by then that row just doesnt show up in the results. All help greatly appreciated.
SELECT travisor_tradesperson.name, travisor_tradesperson.id, travisor_catagory.catname,
travisor_company.cname, travisor_company.description, travisor_company.city, travisor_company.address, travisor_company.postcode, travisor_company.phone,
ROUND(AVG(travisor_review.rating)) as RoundAvgRating, AVG(travisor_review.rating) as AvgRating, COUNT(travisor_review.rating) as NumReviews
FROM `travisor_tradesperson`
INNER JOIN travisor_company
ON travisor_tradesperson.company = travisor_company.id
INNER JOIN travisor_catagory
ON travisor_tradesperson.catagory = travisor_catagory.id
INNER JOIN travisor_review
ON travisor_review.tradesperson = travisor_tradesperson.id
WHERE travisor_catagory.catname = '$catagory'
AND travisor_company.city = '$city'
GROUP BY travisor_tradesperson.name, travisor_catagory.catname, travisor_company.cname,
travisor_company.description
ORDER BY AvgRating DESC, NumReviews DESC
Left join travisor_review instead of Inner Join. Inner join will only find records that are present in both tables. If you have no reviews for that tradesperson record, it will drop from the results set.
Left join will return a NULL if it cannot match on the join predicate. In this case, the tradesperson will return but with a NULL. Convert the NULL to a 0 if needed and that should fix your AVG.
I'm really struggling with this query and I hope somebody can help.
I am querying across multiple tables to get the dataset that I require. The following query is an anonymised version:
SELECT main_table.id,
sub_table_1.field_1,
main_table.field_1,
main_table.field_2,
main_table.field_3,
main_table.field_4,
main_table.field_5,
main_table.field_6,
main_table.field_7,
sub_table_2.field_1,
sub_table_2.field_2,
sub_table_2.field_3,
sub_table_3.field_1,
sub_table_4.field_1,
sub_table_4.field_2
FROM main_table
INNER JOIN sub_table_4 ON sub_table_4.id = main_table.id
INNER JOIN sub_table_2 ON sub_table_2.id = main_table.id
INNER JOIN sub_table_3 ON sub_table_3.id = main_table.id
INNER JOIN sub_table_1 ON sub_table_1.id = main_table.id
WHERE sub_table_4.field_1 = '' AND sub_table_4.field_2 = '0' AND sub_table_2.field_1 != ''
The query works, the problem I have is sub_table_1 has a revision number (int 11). Currently I get duplicate records with different revision numbers and different versions of sub_table_1.field_1 which is to be expected, but I want to limit the result set to only include results limited by the latest revision number, giving me only the latest sub_table_1_field_1 and I really can not figure it out!
Can anybody lend me a hand?
Many Thanks.
It's always important to remember that a JOIN can be on a subquery as well as a table. You could build a subquery that returns the results you want to see then, once you've got the data you want, join it in the parent query.
It's hard to 'tailor' an answer that's specific to you problem, as it's too obfuscated (as you admit) to know what the data and tables really look like, but as an example:
Say table1 has four fields: id, revision_no, name and stuff. You want to return a distinct list of name values, with their latest version of stuff (which, we'll pretend varies by revision). You could do this in isolation as:
select t.* from table1 t
inner join
(SELECT name, max(revision_no) maxr
FROM table1
GROUP BY name) mx
on mx.name = t.name
and mx.maxr = t.revision_no;
(Note: see fiddle at the end)
That would return each individual name with the latest revision of stuff.
Once you've got that nailed down, you could then swap out
INNER JOIN sub_table_1 ON sub_table_1.id = main_table.id
....with....
INNER JOIN (select t.* from table1 t
inner join
(SELECT name, max(revision_no) maxr
FROM table1
GROUP BY name) mx
on mx.name = t.name
and mx.maxr = t.revision_no) sub_table_1
ON sub_table_1.id = main_table.id
...which would allow a join with a recordset that is more tailored to that which you want to join (again, don't get hung up on the actual query I've used, it's just there to demonstrate the method).
There may well be more elegant ways to achieve this, but it's sometimes good to start with a simple solution that's easier to replicate, then simplify it once you've got the general understanding of the what and why nailed down.
Hope that helps - as I say, it's as specific as I could offer without having an idea of the real data you're using.
(for the sake of reference, here is a fiddle with a working version of the above example query)
In your case where you only need one column from the table, make this a subquery in your select clause instead of than a join. You get the latest revision by ordering by revision number descending and limiting the result to one row.
SELECT
main_table.id,
(
select sub_table_1.field_1
from sub_table_1
where sub_table_1.id = main_table.id
order by revision_number desc
limit 1
) as sub_table_1_field_1,
main_table.field_1,
...
FROM main_table
INNER JOIN sub_table_4 ON sub_table_4.id = main_table.id
INNER JOIN sub_table_2 ON sub_table_2.id = main_table.id
INNER JOIN sub_table_3 ON sub_table_3.id = main_table.id
WHERE sub_table_4.field_1 = ''
AND sub_table_4.field_2 = '0'
AND sub_table_2.field_1 != '';
I am attempting to create a subquery in Access but I am receiving an error stating that one record can be returned by this subquery. I am wanting to find the top 10 companies that have the most pets then I want to know the name of those pets. I have never created a subquery before so I am not sure where I am going wrong. Here is what I have:
SELECT TOP 10 dbo_tGovenrnmentRegulatoryAgency.GovernmentRegulatoryAgency
(SELECT dbo_tPet.Pet
FROM dbo_tPet)
FROM dbo_tPet INNER JOIN dbo_tGovenrnmentRegulatoryAgency ON
dbo_tPet.GovernmentRegulatoryAgencyID =
dbo_tGovenrnmentRegulatoryAgency.GovernmentRegulatoryAgencyID
GROUP BY dbo_tGovenrnmentRegulatoryAgency.GovernmentRegulatoryAgency
ORDER BY Count(dbo_tPet.PetID) DESC;
Consider this solution, requiring a subquery in the WHERE IN () clause:
SELECT t1.GovernmentRegulatoryAgency, dbo_tPet.Pet,
FROM dbo_tPet
INNER JOIN dbo_tGovenrnmentRegulatoryAgency t1 ON
dbo_tPet.GovernmentRegulatoryAgencyID = t1.GovernmentRegulatoryAgencyID
WHERE t1.GovernmentRegulatoryAgency IN
(SELECT TOP 10 t2.GovernmentRegulatoryAgency
FROM dbo_tPet
INNER JOIN dbo_tGovenrnmentRegulatoryAgency t2 ON
dbo_tPet.GovernmentRegulatoryAgencyID = t2.GovernmentRegulatoryAgencyID
GROUP BY t2.GovernmentRegulatoryAgency
ORDER BY Count(dbo_tPet.Pet) DESC);
Table aliases are not needed but I include them for demonstration.
This should hopefully do it:
SELECT a.GovernmentRegulatoryAgency, t.NumOfPets
FROM dbo_tGovenrnmentRegulatoryAgency a
INNER JOIN (
SELECT TOP 10 p.GovernmentRegulatoryAgencyID, COUNT(p.PetID) AS NumOfPets
FROM dbo_tPet p
GROUP BY p.GovernmentRegulatoryAgencyID
ORDER BY COUNT(p.PetID) DESC
) t
ON a.GovernmentRegulatoryAgencyID = t.GovernmentRegulatoryAgencyID
In a nutshell, first get the nested query sorted, identifying what the relevant agencies are, then inner join back to the agency table to get the detail of the agencies so picked.
I want to see only one record from the joined table fr_movements with the newest sched_date yet I am always getting the oldedst sched_date. Since the ORDER BY sorts by the sched_date and I am grouping by the people.ID I am getting only one record from fr_movements as expected, just the wrong one.
SELECT `fr_movements`.`ID`, fr_movements_list.movement_type,
fr_movements.sched_date, fr_movements.comp_date, people.firstname, people.lastname
FROM fr_movements
LEFT JOIN people ON people.ID = fr_movements.`people_id`
LEFT JOIN fr_movements_list ON (fr_movements.move_type_id = fr_movements_list.ID)
WHERE fr_movements.org_id = 25 AND fr_movements.move_type_id IN (54,53,52,51,50,55)
GROUP BY people.ID
ORDER BY people.org_name, fr_movements.sched_date ASC
Anybody know how to do this properly?
as #bluefeet mentioned
you are using GROUP BY incorrectly. GROUP BY is supposed to be used with an aggregate function
You need to put all columns after GROUP BY, but it is complicated. I think DISTINCT might help you. like this:
SELECT *
FROM
(
SELECT DISTINCT people.org_name, `fr_movements`.`ID`, fr_movements_list.movement_type,
fr_movements.sched_date, fr_movements.comp_date, people.firstname, people.lastname
FROM fr_movements
LEFT JOIN people ON people.ID = fr_movements.`people_id`
LEFT JOIN fr_movements_list ON (fr_movements.move_type_id = fr_movements_list.ID)
WHERE fr_movements.org_id = 25
AND fr_movements.move_type_id IN (54,53,52,51,50,55)
) x
ORDER BY org_name, sched_date ASC
If not works, would you post your data & schema into sqlfiddle? That makes us happy.
Please I need to figure out what I am doing wrong. I created this inner join code for mysql. it works but it gives me repeated values like repeating a particular row twice or categoryid twice. each of the tables(users,paymentnotification,monthlyreturns) has the categoryid used to check and display the username(users.pname) from the user table, then check and display those that have made payment from the monthly returns and payment table using the categoryid.
$r="SELECT monthlyreturns.categoryid, monthlyreturns.month, monthlyreturns.quarter, monthlyreturns.year,paymentnotification.amount, users.pname, monthlyreturns.ototal, paymentnotification.payee, status
FROM paymentnotification
INNER JOIN (monthlyreturns INNER JOIN users ON monthlyreturns.categoryid=users.categoryid)
ON monthlyreturns.categoryid=paymentnotification.categoryid
ORDER BY monthlyreturns.categoryid DESC";
I think the query you want is more like this:
SELECT b.categoryid, b.month, b.quarter, b.year, a.amount, c.pname, b.ototal, a.payee, status
FROM paymentnotification a
INNER JOIN monthlyreturns b
ON a.categoryid = b.categoryid
INNER JOIN users c
ON b.categoryid = c.categoryid
ORDER BY b.categoryid DESC
The way you are doing the correlations doesn't seem clear and may cause problems. Try this one out and see what happens. If its still doing duplicates, perhaps the nature of the data require further filtering.
Assuming I understand what you're trying to do, you are not joining your tables properly. Try joining one at a time
SELECT DISTINCT monthlyreturns.categoryid, monthlyreturns.month, monthlyreturns.quarter, monthlyreturns.year,paym entnotification.amount, users.pname, monthlyreturns.ototal, paymentnotification.payee, status
FROM paymentnotification
INNER JOIN monthlyreturns
ON paymentnotification.categoryid = monthlyreturns.categoryid
INNER JOIN users
ON monthlyreturns.categoryid = users.categoryid
ORDER BY monthlyreturns.categoryid DESC
I don't see any problem.. I get 4 result rows: check this fiddle http://sqlfiddle.com/#!2/165a22/5
this is the query I used:
SELECT m.categoryid, m.month, m.quarter, m.year,p.amount, u.pname, m.ototal, p.payee, m.status
FROM paymentnotification p JOIN monthlyreturns m ON p.categoryid = m.categoryid
JOIN users u ON u.categoryid = m.categoryid
ORDER BY m.categoryid DESC
there are no duplicated rows, just "unique" rows if you consider every column you choose.
Hope it helps
SELECT M.categoryid, M.month, M.quarter, M.year, M.ototal,
P.amount, P.payee, P.status,
U.pname
FROM paymentnotification AS P
INNER JOIN monthlyreturns AS M ON P.categoryid = M.categoryid
INNER JOIN users AS U ON M.categoryid = U.categoryid
ORDER BY M.categoryid DESC