I have these tables :
I don't know how I can write a statement, that takes emails from Table "Firm", that have Location_id = '1' and Category_id = '130';
I know that I should use JOINs, but I'm not sure how to go from there.
SELECT Firm.email
FROM Firm
INNER JOIN FirmID ON Firm.firma_id = FirmID.firma_id
WHERE FirmID.location_id = '1'
AND FirmID.Category_id = '130'
Should be as simple as doing the following:
SELECT email
FROM Firm, FirmID
WHERE Firm.firma_id = FirmID.firma_id
AND FirmID.location_id = 1
AND FirmID.category_id = 130;
It does a join behind the scenes, but can be a bit clearer to understand than using the JOIN keyword.
You could do:
SELECT f.email
FROM Firm f
WHERE f.firma_id =
(
SELECT ff.firma_id
FROM FirmID ff
WHERE ff.location_id = 1
AND ff.category_id = 130
)
Using an inner select.
But using JOINS is in the long term the way to go, what have you tried and what's not working?
Related
review table has store_idx, user_idx etc...
I want to create a query sentence that gets information about the store to which the user has bookmarked with the user_id value entered.
The query sentence I made is
select A.store_name
, A.store_img
, count(B.store_idx) as review_cnt
from board.store A
Left
Join board.review B
On A.store_idx is B.store_idx
where store_idx is (select A.store_idx from bookmark where user_id = ?)
However, nothing came out as a result.
Help me..
Please use below Query:
SELECT store_name
, store_img
, SUM(review_cnt) AS review_cnt
FROM
( SELECT DISTINCT A.store_name
, A.store_img
, CASE WHEN B.store_idx IS NULL THEN 0 ELSE 1 END AS review_cnt
FROM bookmark br
JOIN board.store A
ON A.store_idx = br.store_idx
LEFT
JOIN board.review B
ON A.store_idx = B.store_idx
WHERE br.user_id = ?
)T
The WHERE clause is obviously filtering out all rows. We can't do much about that. But your query is also lacking a GROUP BY, the table aliases can be improved, and the join condition is not correct.
So, try this version:
select s.store_name, s.store_img, count(b.store_idx) as review_cnt
from board.store s left join
board.review r
on s.store_idx = r.store_idx
where b.store_idx in (select b.store_idx
from bookmark b
where b.user_id = ?
);
I have the following Database Design:
Database Design
I want to get all Information from table 'info' where the id IS NOT in table 'archived'. To do so I wrote:
SELECT *
FROM traffic_info i
LEFT JOIN
traffic_info_archived a ON (i.info_id = a.info_id)
WHERE
i.branch_id = 4 AND i.user_id = 7 a.info_id IS NULL ORDER BY i.info_date_from ASC
This works as expected.
The next challenge is to only show information that are also included in the 'published' table. To get this done I have expanded my previous query to :
SELECT *
FROM traffic_info i
LEFT JOIN
traffic_info_archived a ON (i.info_id = a.info_id)
RIGHT JOIN
traffic_info_publised p ON (i.info_id = p.info_id)
WHERE
i.branch_id = 4 AND a.info_id AND i.user_id = 7 IS NULL ORDER BY i.info_date_from ASC
This does also work as expected.
The final challenge is to Order this result according to table 'read'. Information´s id that are NOT in table 'read' should be ordered ASC. But even if its id does not appear in table 'read' they should not be excluded from the query output. BUT the primary ORDER should be
i.info_date_from ASC
I hope this is understandable, my English is not the best :) If not, please comment and I will do my best to make it understandable. Hope some can help!
I´ve tried to create a SQLFiddle, but I wasn´t able to create a runnable example, sorry for that.
UPADTE:
Using the approach from #Dylan Su
SELECT *
FROM traffic_info i
LEFT JOIN
traffic_info_archived a ON (i.info_id = a.info_id)
INNER JOIN
traffic_info_publised p ON (i.info_id = p.info_id)
WHERE
i.branch_id = 4 AND a.info_id AND i.user_id = 7 IS NULL
ORDER BY
CASE WHEN NOT EXISTS(SELECT 1 FROM read WHERE i.info_id = read.info_id)
THEN i.info_date_from END ASC;
the goal is nearer then it ever was :)
Sample Data output
Both entries marked with a red "X" are in table read. Therefore id 3 should be last the, in the middle 1 and 2 at the top.
So the last thing to archive is to do the correct order of table read. I´ve tried sth like:
(SELECT 1 FROM traffic_info_read WHERE i.info_id = traffic_info_read.info_id ORDER BY traffic_info_read.info_id DESC)
But that didn´t had any influnce.
Try this:
SELECT *
FROM traffic_info i
LEFT JOIN
traffic_info_archived a ON (i.info_id = a.info_id)
INNER JOIN
traffic_info_publised p ON (i.info_id = p.info_id)
WHERE
i.branch_id = 4 AND a.info_id AND i.user_id = 7 IS NULL
ORDER BY
EXISTS(SELECT 1 FROM read WHERE i.info_id = read.info_id) ASC,
i.info_date_from ASC;
The Answer of #Dylan Su is absolutely correct and I won´t unmark it as accepted.
However, based on the Information I gained from the conversation I have created another solution, that doesn´t make use of sub query.
I heard that using just JOIN´s will result in better performance, I don´t know if it´s correct and I don´t have that much test data currently to find out, but here is the solution using no sub query.
SELECT *
FROM traffic_info i
LEFT JOIN
traffic_info_archived a ON (i.info_id = a.info_id)
INNER JOIN
traffic_info_published p ON (i.info_id = p.info_id)
LEFT JOIN
traffic_info_read r ON (i.info_id = r.info_id)
WHERE
i.branch_id = 4 AND a.info_id IS NULL ORDER BY r.info_id IS NULL DESC, i.info_date_from ASC
;
p = Patient.find(30)
p.patient_problems
The above code generates the following query
SELECT `patient_problem`.* FROM `patient_problem` WHERE `patient_problem`.`patient_id` = 30 AND (`patient_problem`.`record_status_id` = 1)
But is there any way to assign/use alias table_name like
p.patient_problems(:alias=>'p1') # just for Ex.. This code will not work
p.patient_problems(:alias=>'p2') # just for Ex.. This code will not work
So it will generate the following queries
SELECT `p1`.* FROM `patient_problem` AS `p1` WHERE `p1`.`patient_id` = 30 AND (`p1`.`record_status_id` = 1)
SELECT `p2`.* FROM `patient_problem` AS `p2` WHERE `p2`.`patient_id` = 30 AND (`p2`.`record_status_id` = 1)
Additional Info
My problem is when I try to use joins
p.patient_problems(:all,:joins=>joins)
I get this error
ActionView::Template::Error (Mysql2::Error: Not unique table/alias: 'patient_problem': SELECT `patient_problem`.* FROM `patient_problem` LEFT OUTER JOIN party on party.id = patient_problem.patient_id
LEFT OUTER JOIN party_identifier on party.id = party_identifier.party_id
LEFT OUTER JOIN blood_type on blood_type.id = party.blood_type_id
LEFT OUTER JOIN education_level on education_level.id = party.education_level_id
LEFT OUTER JOIN religion on religion.id = party.religion_id
LEFT OUTER JOIN living_arrangement on living_arrangement.id = party.living_arrangement_id
LEFT OUTER JOIN patient_problem patient_problem on patient_problem.patient_id = party.id and patient_problem.record_status_id = 1
left join (select user_type,username,user_id,auditable_id from (select MAX(id) id from audits where audits.auditable_type = 'PatientProblem' and user_type is not null group by auditable_id ) t inner join audits v on v.id=t.id ) entered_by1 on entered_by1.auditable_id = patient_problem.id
left outer join user user1 on entered_by1.user_id = user1.id
left outer join party as party_user1 on party_user1.id = user1.person_id
LEFT OUTER JOIN patient_patient_search patient_patient_search1 on patient_patient_search1.patient_id = party.id
left join search search1 on patient_patient_search1.patient_search_id = search1.id
and patient_patient_search1.patient_search_id = '75' WHERE `patient_problem`.`patient_id` = 45 AND (`patient_problem`.`record_status_id` = 1) AND ( (patient_problem.occurrence_date > '2013-01-01 00:00:00' and patient_problem.occurrence_date < '2013-06-30 23:59:59' and patient_problem.patient_problem_status_id in (5) and patient_problem.code is not null and patient_problem.code in ('10725009') ) and ( patient_patient_search1.patient_search_id in (75.0) ) ))
Ofcourse I could do some string manipulation on the generated joins query and set alias to patient_problem. But I thought setting alias for associations would be more cleaner since the joins query generated are unpredictable(in my scenario)
I am not sure what the variable joins is or how it was constructed. To alias tables in a join build your query like
Rails 3
PatientProblem.joins("as p1 OUTER JOIN patient_problem as p2 on ...")
or
PatientProblem.find(:all, :joins => "as p1 OUTER JOIN patient_problem as p2 ON ...")
you can make singleton methods for that and write the query one time and use may time like
def self.p1
#your active record query here.
end
and call like
PatientProblem.p1
Update
You can simply change the table name in your code:
Patient.table_name="p2"
I'm not sure if this would break anything else though ... so good luck!
Orignal Answer
One solution may be to define a separate model for each type of patient_problem and then do something like this:
class PatientProblem2 < ActiveRecord::Base
self.set_table_name "p2"
...
end
Another solution may be to use the ActiveRecord query interface which will allows for significant query flexibility:
http://guides.rubyonrails.org/active_record_querying.html
Perhaps you can be more specific on the nature problem you are trying to solve.
I have the following model:
I've been at this for a while and still don't know how to tackle it properly. Already looked at joining two aliased subqueries, joining two views, and tried a gynormous and ugly all-in one query, none of which worked.
My question is simple:
How can I select deivce_names.name and match them to a model and manufacturer?
SELECT
name, manufacturer, model
FROM
device_names
JOIN devices ON (device_names.id = name_id)
JOIN devices_generic ON (generic_device_id = devices_generic.id)
JOIN device_manufacturers ON (manufacturer_id = device_manufacturers.id)
JOIN device_models ON (model_id = device_models.id)
select
device_names.name as device_name,
device_manufacturers.name as device_manufacturer_name,
device_models.name as device_model_name
from deivce_names
join device on device.name_id = deivce_names.id
join devices_generic on devices_generic.id = devices.generic_device_id
join device_manufacturers on devices_generic.manufacturer_id = device_manufacturers.id
join device_models on device_models.id = devices_generic.model_id
SELECT dm1.manufacturer, dm2.model from device_manufacturers as dm1 join devices_generic as dg on dg.manufacturer_id = dm1.id join device_models as dm2 on dm2.id = dg.model_id join devices as d2 on d2.generic_device_id = dg.id join device_names as dn on dn.id = d2.name_id where name = 'foo'
In the future, you might want to simply put your data into a fiddle and play with it there.
I have the following query:
SELECT CASE WHEN `def_spell`.`type` = 0 THEN `spells_damage`.*
WHEN `def_spell`.`type` = 1 THEN `spells_weaken`.*
END
FROM `def_spell`
LEFT JOIN `spells_damage` ON `def_spell`.`id` = `spells_damage`.`spell_id`
LEFT JOIN `spells_weaken` ON `def_spell`.`id` = `spells_weaken`.`spell_id`
WHERE `def_spell`.`id` = 1;
Hopefully that makes sense... I'm basically trying to select everything from spells_damage providing type is 0 and everything from spells_weaken providing type is 1.
I'd also like to select everything from def_spell regardless.
Can someone please fix the query? I've never used cases like this before and not sure how to.
You can't use a CASE to choose between the output of the two tables like that.
Unfortunately, that's the easy bit; working out (a) what you're trying to do and (b) achieving an equivalent result is going to take a little longer.
It would be easier if you gave us information about the columns in the Spells_Weaken and Spells_Damage table. Presumably, there are some differences; otherwise, you'd have a single table. Indeed, a single Spells table might still be a better design.
Let's put doubts aside. Assuming that the Spells_Weaken and Spells_Damage tables are UNION-compatible, you can use a UNION to achieve the result:
SELECT s.*, d.*
FROM def_spell AS s
LEFT JOIN spells_damage AS d ON s.id = d.spell_id
WHERE s.type = 0
AND s.id = 1
UNION
SELECT s.*, w.*
FROM def_spell AS s
LEFT JOIN spells_weaken AS w ON s.id = w.spell_id
WHERE s.type = 1
AND s.id = 1;
You won't be able to do that. You will need to either split it into two queries, or manually specify each of the columns with the CASE statement.
SELECT CASE WHEN a.`type` = 0 THEN b.col1
WHEN a.`type` = 1 THEN c.col1
END AS col1
, CASE WHEN a.`type` = 0 THEN b.col2
WHEN a.`type` = 1 THEN c.col2
END AS col2
FROM `def_spell` a
LEFT JOIN `spells_damage` b ON a.`id` = b.`spell_id`
LEFT JOIN `spells_weaken` c ON a.`id` = c.`spell_id`
WHERE a.`id` = 1;