I have problem that I hope someone can help me with.
SELECT a.country_name, s.state_name, c.city_id,
LEAST (c.next_1, c.next_2, c.next_3) AS next_visit,
MAX(v.visit_time) AS last_visit
FROM city c
INNER JOIN country a ON a.id = c.country
INNER JOIN state s ON s.id = c.state
INNER JOIN visit_log v ON CONCAT(c.country, c.state, c.city_id) = CONCAT(v.country, v.state, v.city_id)
GROUP BY CONCAT(v.country, v.state, v.city_id)
ORDER BY a.id ASC, s.id ASC, c.city_id
My main problem now is that I can't get the col_1 and col_2 from the visit_log corresponding with MAX(visit_log)
SQLfiddle
You can add the "latest" requirement to the join condition:
SELECT *
FROM city c
JOIN country a
ON a.id = c.country
JOIN state s
ON s.id = c.state
JOIN visit_log v
ON v.country = c.country
AND v.state = c.state
AND v.city_id = c.city_id
AND visit_time =
(
SELECT MAX(visit_time)
FROM visit_log v2
WHERE v2.country = c.country
AND v2.state = c.state
AND v2.city_id = c.city_id
)
You can find many other approaches in the greatest-n-per-group+mysql tag. For optimal speed you'd use an approach using variables.
You can try this:-
SELECT C.NAME, S.NAME, CN.ID, NV.Next_visit_1, VL.visited
FROM COUNTRY C INNER JOIN next_visit NV ON C.ID = NV.Country
INNER JOIN STATE S ON NV.State = S.ID
JOIN CITY
INNER JOIN visitor_log VL ON CONCAT(NV.country, NV.state, NV.city) = CONCAT(VL.country, VL.state, VL.city)
Related
I want to convert this query in such a way so it does not have any 'exists' and uses only simple joins.
select t.Teacher_id, t.Teacher_name, a.marks, a.grade_ID
from Grades a
left join students s on a.student_ID = s.student_ID
left join Teachers t on t.Teacher_ID = s.Teacher_ID
where 1=1 and t.Teacher_id = 1807600
and exists(
select p.Payment_ID from payments p
inner join lookups l on (l.lookup_id = p.status_id and l.lookup_key in ('condition1','condition2'))
where p.student_ID = a.student_ID
)
I tried something like:
select t.Teacher_id, t.Teacher_name, a.marks, a.grade_ID
from Grades a
left join students s on a.student_ID = s.student_ID
left join Teachers t on t.Teacher_ID = s.Teacher_ID
inner join payments p on p.student_ID = a.student_ID
inner join lookups l on (l.lookup_id = p.status_id and l.lookup_key in ('condition1','condition2'))
where 1=1 and t.Teacher_id = 1807600
But I'm not getting the right results. Can you please help. Thanks.
I suppose you could use group by, but this restricts the maintainability of the script for the simple sake of not using EXISTS().
select t.Teacher_id, t.Teacher_name, a.marks, a.grade_ID
from Grades a
left join students s on a.student_ID = s.student_ID
left join Teachers t on t.Teacher_ID = s.Teacher_ID
inner join payments p on p.student_ID = a.student_ID
inner join lookups l on (l.lookup_id = p.status_id and l.lookup_key in ('condition1','condition2'))
where t.Teacher_id = 1807600
group by t.Teacher_id, t.Teacher_name, a.marks, a.grade_ID
I have a big multiple table query join select where some values are optional.
This is the query:
SELECT a.date_in, a.date_out, b.name, b.phone, b.birthdate,
b.country, b.hotel, b.room_nr, b.passport_nr, c.email,
d.size, e.name, GROUP_CONCAT(DISTINCT g.service), GROUP_CONCAT(DISTINCT h.service)
, GROUP_CONCAT(DISTINCT i.time), GROUP_CONCAT(DISTINCT j.location)
FROM reservation a, rider b, user c,
bike_size d, bike e, services_reservation f, services g,
bike_shipping h, bike_shipping_reservation i
, bike_shipping_location j WHERE a.rider_id = b.id
AND b.user_id = c.id AND a.bike_size_id = d.id AND
d.bike_id = e.id AND a.id = f.reservation_id AND
f.services_id = g.id
AND h.id = i.bike_shipping_id AND a.id = i.reservation_id
AND i.bike_shipping_location_id = j.id
AND a.id = 80
In the tables from the query above, the table named services_reservation with the following columns (id, services_id, reservation_id) is completely empty in this case, which makes the values that I select from the table bike_shipping_reservation NULL.
How can I make some tables that I select from optional in case they are empty?
Here is the SQL Fiddle with 1 empty table, you can see the NULL results at the end (only GROUP_CONCAT(DISTINCT g.service) should be NULL).
http://sqlfiddle.com/#!9/ee31b/6
Here is the SQL Fiddle with all tables having values in there columns, you can see that all values are returned not NULL.
http://sqlfiddle.com/#!9/8bc033/34
Any thoughts?
Use left join where the table (or the row) are empty on don't match
SELECT a.date_in, a.date_out, b.name, b.phone, b.birthdate,
b.country, b.hotel, b.room_nr, b.passport_nr, c.email,
d.size, e.name, GROUP_CONCAT(DISTINCT g.service), GROUP_CONCAT(DISTINCT h.service)
, GROUP_CONCAT(DISTINCT i.time), GROUP_CONCAT(DISTINCT j.location)
FROM reservation a
INNER JOIN rider b on a.rider_id = b.id
INNER JOIN user c on b.user_id = c.id
INNER JOIN bike_size d on a.bike_size_id = d.id
INNER JOIN bike e ON d.bike_id = e.id
LEFT JOIN services_reservation f on a.id = f.reservation_id
INNER JOIN services g on f.services_id = g.id
INNER JOIN bike_shipping_reservation i on a.id = i.reservation_id
INNER JOIN bike_shipping h ON h.id = i.bike_shipping_id
INNER JOIN bike_shipping_location j on i.bike_shipping_location_id = j.id
where a.id = 80
Here's a picture of my database structure:
With help from users on here I've managed to put together quite a complex SQL statement using GROUP_CONCAT:
SELECT
t1.Name AS Teacher_Name,
t2.Name AS Observer_Name,
o.Datetime AS Datetime,
o.Type AS Type,
o.Year_Group AS Year_Group,
o.Class_Name AS Class_Name,
c.Title AS Course_Name,
GROUP_CONCAT(l.Title) AS Focus,
o.Achievement_Grade AS Achievement_Grade,
o.Behaviour_Grade AS Behaviour_Grade,
o.Teaching_Grade AS Teaching_Grade,
GROUP_CONCAT(cl1.Title) AS Positive,
GROUP_CONCAT(cl2.title) AS Development,
o.Notes AS Notes
FROM observations o
LEFT JOIN teachers t1
ON o.Teacher_ID = t1.Teacher_ID
LEFT JOIN teachers t2
ON o.Observer_ID = t2.Teacher_ID
LEFT JOIN courses c
ON o.Course_ID = c.Course_ID
LEFT JOIN foci f
ON o.ID = f.Observation_ID
LEFT JOIN focus_labels l
on f.focus_id = l.id
LEFT JOIN criteria c1
ON o.ID = c1.Observation_ID
LEFT JOIN criteria_labels cl1
on c1.Criteria_ID = cl1.ID AND c1.Type = 'P'
LEFT JOIN criteria c2
ON o.ID = c2.Observation_ID AND c2.Type = 'D'
LEFT JOIN criteria_labels cl2
on c2.Criteria_ID = cl2.ID
GROUP BY o.id
ORDER BY `Datetime` DESC";
This appears to work OK, apart from the fact that Focus, Positive and Development are each repeated depending on the field that has the highest number of concatenations in.
For example, if Positive has Pace,Progress,Attainment but Focus is only Appraisal, it'll be repeated three times (Appraisal,Appraisal,Appraisal).
I've looked this up and I think it could be because I need to GROUP each of these GROUP_CONCAT JOINs. However, I have no idea how to go about this.
Can anyone help? Thanks in advance,
GROUP_CONCAT has DISTINCT attribute that can be applied to remove duplicates.
SELECT
t1.Name AS Teacher_Name,
t2.Name AS Observer_Name,
o.Datetime AS Datetime,
o.Type AS Type,
o.Year_Group AS Year_Group,
o.Class_Name AS Class_Name,
c.Title AS Course_Name,
GROUP_CONCAT(DISTINCT l.Title) AS Focus,
o.Achievement_Grade AS Achievement_Grade,
o.Behaviour_Grade AS Behaviour_Grade,
o.Teaching_Grade AS Teaching_Grade,
GROUP_CONCAT(cl1.Title) AS Positive,
GROUP_CONCAT(cl2.title) AS Development,
o.Notes AS Notes
FROM observations o
LEFT JOIN teachers t1
ON o.Teacher_ID = t1.Teacher_ID
LEFT JOIN teachers t2
ON o.Observer_ID = t2.Teacher_ID
LEFT JOIN courses c
ON o.Course_ID = c.Course_ID
LEFT JOIN foci f
ON o.ID = f.Observation_ID
LEFT JOIN focus_labels l
on f.focus_id = l.id
LEFT JOIN criteria c1
ON o.ID = c1.Observation_ID
LEFT JOIN criteria_labels cl1
on c1.Criteria_ID = cl1.ID AND c1.Type = 'P'
LEFT JOIN criteria c2
ON o.ID = c2.Observation_ID AND c2.Type = 'D'
LEFT JOIN criteria_labels cl2
on c2.Criteria_ID = cl2.ID
GROUP BY o.id
ORDER BY `Datetime` DESC";
select
s.id, s.description, s.improvement, s.previous_year_id,
s.current_year_id, s.first_name, s.last_name, s.username,
s.finding, s.action, s.share, s.learned, s.timestamp,
d.title as department_title,
group_concat(g.title SEPARATOR \' | \') as strategic_goals,
y1.year as current_year_title, y2.year as previous_year_title,
u.summary_id, u.file_name as file_name
from
summary s, year y1, year y2, strategic_goal_entries sge,
goal g, department d, uploads u
where
s.id = sge.summary_id
and
s.current_year_id = y1.id
and
s.previous_year_id = y2.id
and
sge.goal_id = g.id
and
s.id = u.summary_id
and
s.department_id = d.id
and
s.department_id = '4'
group by
s.id
This only returns records from the summary table that has a relating record in the uploads table (s.id = uploads.summary_id) that contain a value within the uploads.summary_id field
I want to return all records, whether or not it has a file associated with it.
Any help is appreciated.
Suggest refactoring this SQL query to use ANSI joins. To achive your goal, you'd want a LEFT JOIN instead:
SELECT /*your columns*/
from summary s
INNER JOIN year y1 ON s.current_year_id = y1.id
INNER JOIN year y2 ON s.previous_year_id = y2.id
INNER JOIN strategic_goal_entries sge ON s.id = sge.summary_id
INNER JOIN goal g ON sge.goal_id = g.id
INNER JOIN department d ON s.department_id = d.id
LEFT JOIN uploads u ON s.id = u.summary_id
WHERE s.department_id = '4'
group by s.id
Hi Order By not working on MySql
the code is as follows,
select * from School where School.type = 'HighSchool'
order by (select locations.name from locations inner join School_locations
on locations.id = School_locations.location_id where
School_locations.School_id = School.id and locations.location_country = 'US' limit 1)
and the output is displaying same for both ascending as well as descending how to solve this problem
I don't think you'd need to do the subquery:
SELECT s.*
FROM School s
INNER JOIN School_locations sl ON (s.id = sl.School_id)
INNER JOIN locations l ON (l.id = sl.location_id)
WHERE l.location_country = 'US' AND s.type = 'High school'
ORDER BY l.name
select school.* from school
inner join school_locations on school_locations.schoolid = school.school_id
inner join locations on locations.location.id = school_locations.locationid
where
locations.location_country = 'US' and school.type = 'HighSchool'
order by
locations.name
limit 1
you can use this query
select School.* from School inner join School_locations
on School_locations.School_id = School.id
inner join locations
on locations.id = School_locations.location_id
where locations.location_country = 'US' and School.type = 'HighSchool'
order by locations.name limit 1