Query Definition:
Select Students who have a grade of 85 or better in art
and
who also have a grade of 85 or better in any computer course
QUERY(explained in 3 sections is single query executed on MySQLWorkBench):
select Students.StudFirstName,Student_Schedules.Grade
from
(Select Distinct Students.StudentID,Students.StudFirstName,Student_Schedules.Grade
from (((Students
Inner Join Student_Schedules
On Student_Schedules.StudentID = Students.StudentID)
Inner Join Classes
On Classes.ClassID = Student_Schedules.ClassID)
Inner Join Subjects
On Subjects.SubjectID = Classes.SubjectID)
Inner Join Categories
On Subjects.CategoryID = Categories.CategoryID
where Categories.CategoryDescription = 'Art' and Student_Schedules.Grade >= 85)
As Stud_Art
Above code extracts Students who have a grade of 85 or better in Art
Inner Join
(Select Distinct Students.StudentID,Students.StudFirstName,Student_Schedules.Grade
from (((Students
Inner Join Student_Schedules
On Student_Schedules.StudentID = Students.StudentID)
Inner Join Classes
On Classes.ClassID = Student_Schedules.ClassID)
Inner Join Subjects
On Subjects.SubjectID = Classes.SubjectID)
Inner Join Categories
On Subjects.CategoryID = Categories.CategoryID
WHERE Categories.CategoryDescription LIKE '%Computer%' AND Student_Schedules.Grade >= 85)
As Stud_CS
Above code extracts Students who have a grade of 85 or better in Computer
On Stud_CS.StudentID = Stud_Art.StudentID;
Above code matches StudentID from Art and Computer
Error From MySQLWorkBench:
Error Code: 1054. Unknown column 'Students.StudFirstName' in 'field list'
The above Query may be solved by SubQuery technique but i want to learn how is it possible with Inner Join technique
You are trying to retrieve Students.StudFirstName and Student_Schedules.Grade but your table aliases are Stud_Art and Stud_CS. Might that be the issue?
I think that the first part should be like this:
select Stud_Art.StudFirstName,Stud_Art.Grade
Related
I have four tables, three of which are pretty static: haul_types, dumpster_type_team (the dumpster_type_team has the many-to-many relationship between dumpster_types and teams), and users. The fourth table, hauls, has transactional data.
haul_types:
id
name
dumpster_type_team:
id
dumpster_type_id
team_id
users:
id
first_name
last_name
is_driver
team_id
hauls:
haul_type_id
haul_status_id
set_dumpster_type_id
completed_driver_id
team_id
I would like a query that has a combination of dumpster_types, haul_types, and drivers (users) and a count of the hauls they were involved in. In some cases, there should be a count of zero because some drivers haven't completed hauls for every haul_type / dumpster type combination.
Here's the query I have so far that seems to be behaving as if it is an inner join because the records are getting filtered to only show where there are matches:
SELECT
c.haul_type_id,
c.dumpster_type_id,
c.driver_id,
count(h.id) AS haul_count
FROM
hauls h
RIGHT JOIN ( SELECT DISTINCT
ht.id AS haul_type_id,
dtt.dumpster_type_id AS dumpster_type_id,
dtt.team_id AS team_id,
u.id AS driver_id
FROM
haul_types ht
CROSS JOIN dumpster_type_team dtt
CROSS JOIN users u
WHERE
u.team_id = dtt.team_id
AND u.is_driver = TRUE) c ON c.haul_type_id = h.haul_type_id
AND c.dumpster_type_id = h.set_dumpster_type_id
AND c.driver_id = h.completed_driver_id
AND c.team_id = h.team_id
WHERE
h.team_id = 9
AND h.haul_status_id = 3
AND h.completed_driver_id IS NOT NULL
GROUP BY
c.haul_type_id, c.dumpster_type_id, c.driver_id
When I run the subquery in isolation:
SELECT DISTINCT
ht.id AS haul_type_id,
dtt.dumpster_type_id AS dumpster_type_id,
dtt.team_id AS team_id,
u.id AS driver_id
FROM
haul_types ht
CROSS JOIN dumpster_type_team dtt
CROSS JOIN users u
WHERE
u.team_id = dtt.team_id
AND u.is_driver = TRUE
I get the results I want: a row for each permutation of haul_type, dumpster_type, driver_id, and team_id. However, when I run the entire query, I get filtered results despite the right join.
What I would like to have is the following:
If I have 4 haul_types: delivery, swap, live, pickup
and 2 dumpster_types: 10YD, 15YD
and 2 drivers: 1, 2
I would like a haul count for the combination of haul_type, dumpster_type, and driver. If there are no hauls matching the row, show 0:
Any help is appreciated. Thank you
The description of the question and the query seem to have little to do with each other. I don't know what a "pivot table" is supposed to be.
I would like a query that has a combination of dumpster_types, haul_types, and drivers (users) and a count of the hauls they were involved in.
This sounds like a cross join to generate the rows and then a left join/group by to calculate the results:
select d.dumpster_id, ht.haul_type_id, d.driver_id, count(h.driver_id)
from dumpster_types d cross join
haul_types ht cross join
drivers d left join
hauls h
on h.dumpster_id = d.dumpster_id and
h.haul_type_id = ht.haul_type_id and
h.driver_id = d.driver_id
group by d.dumpster_id, ht.haul_type_id, d.driver_id;
Running the query #GordonLinoff provided, exposed the issue I was facing - when applying a where clause on the top level query, the results were getting filtered to only matches. I moved the where clause to individual subqueries and now I am getting all expected results.
Not sure if this is the most efficient way to write it but it yields the correct results:
SELECT
d.dumpster_type_id,
ht.id AS haul_type_id,
u.id AS driver_id,
count(h.id) AS haul_count
FROM (
SELECT
dumpster_type_id,
team_id
FROM
dumpster_type_team
WHERE
team_id = 9) d
CROSS JOIN haul_types ht
CROSS JOIN (
SELECT
users.id
FROM
users
WHERE
users.is_driver = TRUE
AND users.team_id = 9) u
LEFT JOIN (
SELECT
id, set_dumpster_type_id, haul_type_id, completed_driver_id, team_id
FROM
hauls
WHERE
haul_status_id = 3
AND team_id = 9) h ON h.set_dumpster_type_id = d.dumpster_type_id
AND h.haul_type_id = ht.id
AND h.completed_driver_id = u.id
AND h.team_id = d.team_id
GROUP BY
d.dumpster_type_id,
ht.id,
u.id
I am working on a query in which I am getting a list of meter numbers along with there subdivision names.
But when I run my query it's giving me same subdivision names against different meter numbers.
The query is
SELECT DISTINCT ms.`id` AS 'meter_id', ms.`meter_msn` AS 'Meter_Serial_Number', u.`name` AS 'Issued_To'
,ps.`name` AS 'Store', sd.`name` AS 'Name',ms.`historic` AS 'Meter_Version'
FROM `meters` ms
INNER JOIN `ogp_header` ogph ON ms.`issued_user` = ogph.`issuer`
INNER JOIN `project_store` ps ON ogph.`store_id` = ps.`id`
INNER JOIN `user` u ON `ogph`.`issuer` = u.`id`
INNER JOIN `issue_meters` im ON ps.`id` = im.`store_id`
INNER JOIN `survey_hesco_subdivision` sd ON im.`sub_division` =
sd.`sub_div_code`
WHERE ms.`meter_status` = 'Installation Ready' AND ms.`id` NOT IN (SELECT
DISTINCT ogpd.`meter_id` FROM `ogp_detail` ogpd WHERE ogpd.`flag` IN (1,2))
GROUP BY ms.`id`
ORDER BY ms.`id`
The result is
All these 6 meters are from different sub-divisions(NAME in the Result). How can I arrange the query in such a way that there will be distinct subdivision names?
Any help would be highly appreciated.
I have this code:
SELECT A.UNITCODE, B.FORMATIONCODE, C.UPPERFORMATIONCODE, D.UPPERFORMATIONCODE
FROM UNIT AS A.UNITCODE
INNER JOIN FORMATION AS B.FORMATIONCODE
INNER JOIN UPPERFORMATION_UNIT AS C.UPPERFORMATION
INNER JOIN UPPERFORMATION AS D.UPPERFORMATIONCODE
WHERE UNITCODE='7000007'
Can you guys help me how to join 4 tables with specified column?
Assuiming the all 3 related tables have the same UNIT_ID for join with table UNIT
SELECT
A.UNITCODE
, B.FORMATIONCODE
, C.UPPERFORMATIONCODE
, D.UPPERFORMATIONCODE
FROM UNIT AS A
INNER JOIN FORMATION AS B ON B.FORMATIONCODE = A.UNIT_ID
INNER JOIN UPPERFORMATION_UNIT AS C. C.UPPERFORMATION = A.UNIT_ID
INNER JOIN UPPERFORMATION AS D D.UPPERFORMATIONCODE = A.UNIT_ID
WHERE UNITCODE='7000007'
It seems you are confusing table aliases and linking columns.
This is how to give a table an alias name in the query in order to enhance readability:
INNER JOIN formation AS f
where the AS is optional. Most often it is ommited.
This is how to join:
FROM unit AS u
INNER JOIN upperformation_unit AS ufu ON ufu.unitcode = u.unitcode
Well, I don't know the columns linking the tables of course, let alone their names. But I suppose the query would have to look like this more or less:
SELECT
u.unitcode,
f.formationcode,
uf.upperformationcode,
ufu.upperformationcode
FROM unit u
JOIN upperformation_unit ufu ON ufu.unitcode = u.unitcode
JOIN upperformation uf ON uf.upperformationcode = ufu.upperformationcode
JOIN formation f ON f.formationcode uf.formationcode
WHERE u.unitcode = 7000007;
I have some tables in my database, three main ones and one that holds the many-to-many relations.
1. Student (student_id, student_name)
2. Sport (sport_id, sport_name)
3. Departm (depart_id, depart_name)
4. Sch (sch_id, sch_name)
5. StudSport(relationid, studendid, sportid, departid, schid)
What I want to do is e.g. retrieve the name of the department based on the relations when I know the id. I can get the ids like this:
SELECT departid, schid from studsport
inner join Student on student_id = studentid
inner join Sport on sport_id = sportid
where student_id = 1 and sport_id=2
but I want to get the names of the department and the Sch from their corresponding tables, and I dont know how to do that.
As you don't select anything from Student or Sport, you can remove the corresponding inner joins.
SELECT d.depart_name, sch.sch_name FROM StudSport s
INNER JOIN Sch sch ON s.schid = sch.sch_id
INNER JOIN Departm d ON s.departid = d.depart_id
WHERE s.studendid = 1 AND s.sportid = 2
Something like this???
select sch.sch_nam, departm.depart_name,
-- what you have already --
Left outer Join StudSport on Student.student_id = Studsport.studentid and Sport.sport_id = StudSport.sportid
left outer Join Sch on StudSport.schid = Sch.sch_id
left outer join Departm on studsport.depart_id = studsport.departid
This is untested, a fiddle makes it much easier to give answers because of that.
EDIT - I misread your original query - before the downvotes start to rain - fixing it right now.
The way you should use LEFT OUTER and INNER joins is how the data is meant (again, a fiddle will normally be usefull) but it's just a couple of joins from what you have i guess:
select *
from studsport
join student on studsport.studentid = student.student_id
join sport on studsport.sportid = sport.sport_id
left outer Join Sch on StudSport.schid = Sch.sch_id
left outer join Departm on studsport.depart_id = studsport.departid
where student_id = 1 and sport_id=2
I'm having difficulty with some SQL - and finding it hard to describe so please bear with me. I'm trying to select products that have an x number of correct features. To simplify things, the problem I'm having is with a few tables. The relevant information about my tables, is:
products(**product_id**)
features(**feature_id, product_id**, value_id)
featurenames(**feature_id**, name)
featurevalues(**value_id**, value)
I am trying to select all products that, for example, are for sex:male age:children, with age and sex being names in the featurenames table and male and children being values in the featurevalues table. This is part of another bigger query that gets all the products by category, which I haven't included as it will just complicate things. Thank you for your help in advance.
It's the table so nice, you join to it twice.
Select
P.Product_ID
From
Products P
Inner Join Features F1 On P.Product_ID = F1.Product_ID
Inner Join FeatureNames FN1 On F1.Feature_ID = FN1.Feature_ID And FN1.Name = 'sex'
Inner Join FeatureValues FV1 On F1.Value_ID = FV1.Value_ID And FV1.Value = 'male'
Inner Join Features F2 On P.Product_ID = F2.Product_ID
Inner Join FeatureNames FN2 On F2.Feature_ID = FN2.Feature_ID And FN1.Name = 'age'
Inner Join FeatureValues FV2 On F2.Value_ID = FV2.Value_ID And FV1.Value = 'children'