How can I get the name of students by using the section and year_level as arguments? Below is the ERD of my database.
select u.fname
from users u
join students s on u.user_id = s.user_id
join sections sec on s.section_id = sec.section_id
where sec.section_id = 1
and sec.year_level_section = 1
You don't even need to join level table. Actually, you don't need that table at all.
Related
I am currently trying to run a sql statement to pull data from 2 tables I was wondering if someone could help me with my code. I would like to pull Project.Project_ID, Project.StartDate, Project.Users where Project_ID = 1 in both tables.
SELECT Project.Project_ID, Project.StartDate, Project.Users
FROM Project
INNER JOIN UserList ON Project.Project_ID=UserList.Project_ID
WHERE Project.Project_ID = '1';
I am not exactly sure what is your problem statement. If you can provide more details (DB Structure) that would be really helpful.
There could be more that one scenario you want to solve based on your data structure.
The only thing I see here is instead of Project.Users you should have UserList. Users. I assume User list tables having all the users details and it's not a pivot table. If it is then you need another join with User table.
SELECT
Project.Project_ID, Project.StartDate, UserList.Users
FROM
Project
INNER JOIN UserList ON Project.Project_ID=UserList.Project_ID
WHERE
Project.Project_ID = '1';
Please share your Database Structure.
With your model a user can only be linked to one project.
Below is with an joining table UserProject.
This way n users can take part to n projects. (n to n relation)
SELECT
p.id AS projectId,
p.startDate,
u.id AS userId,
u.name,
[...]
FROM
Project AS p,
UserProject AS up,
User AS u
WHERE
p.id = up.projectId
AND u.id = up.userId
AND p.id = 1;
And here is with a 1 to 1 relation
[...]
FROM
Project AS p,
User AS u
WHERE
p.id = u.projectId
AND p.id = 1;
I want to improve my search performance. I want to search the user against the services and specialty. user in listed as per the filter applied either by specialty or by services or can be both.There are 5 tables i want to get the data from all the table
I have below table structure
1) users :- id ,first_name,last_name
2) users_services :- id ,user_id,service_id
3) users_speciality :- id,user_id,specility_id
4) mst_services :- id,name
5) mst_speciality :- id,name
I have used this query to get the result and it works fine.
select u.id,first_name,last_name,location,services.name as service_name,speciality.name as specility_name from users as u
inner join users_services on u.id =users_services.user_id
Inner join mst_services as services on services.id=users_services.service_id
inner join users_speciality on u.id =users_speciality.user_id
Inner join mst_speciality as speciality on speciality.id=users_speciality.service_id WHERE speciality.name ="specificity one"
as per the normalization it seems correct.But when data is more than 1,00,000 that time joining too many table causes may create problem.
what should i do for filter the user according to services and specialty ?
Have you tried like this ?
SELECT users.id,first_name,last_name, mst_services.name as service, mst_speciality.name AS speciality
FROM users
LEFT JOIN users_services ON users.id = users_services.user_id
LEFT JOIN users_speciality ON users.id = users_speciality.user_id
LEFT JOIN mst_services ON service_id = mst_services.id
LEFT JOIN mst_speciality ON speciality_id = mst_speciality.id
WHERE users.id IN
(SELECT user_id FROM users_services
WHERE service_id = (SELECT id FROM mst_services WHERE name = "service one")
UNION ALL
SELECT user_id FROM users_speciality
WHERE speciality_id = (SELECT id FROM mst_speciality WHERE name = "spercial one"))
ORDER BY first_name,last_name,service,speciality
I have two tables users and linkage. I am creating a link between one user to another. Means user A will be linked to user B and vise versa.
Now I want to get the details of linked users for a particular entered user_id. Means If user A is finding his linked Id's then the details of linked id's should be seen.
Linkage has three columns its id, user_id and linked_contact_id.
Users has columns as user_id, user_name,pass etc..
I tried one join but I only get the linked Id's from this not the details of id's.
SELECT * FROM Users INNER JOIN linkage ON linkage.user_id = Users.user_id WHERE linkage.linked_contact_id = 1
output
user_id linked_contact_id
1 4
1 1
1 5
How can I get this?Please help.. Thank you...
You will need to join on the users table a second time:
SELECT u.*, u2.* FROM Users u
INNER JOIN linkage l ON l.user_id = u.user_id
INNER JOIN Users u2 ON l.linked_contact_id = u2.user_id
WHERE l.linked_contact_id = 1
Please note that as you are selecting the same columns twice (in u.*, u2.*), you will probably have to list out each field with an alias to distinguish between them.
Something wrong on your ratio. But it's okay.
Try LEFT JOIN or RIGHT JOIN
SELECT * users
LEFT JOIN linkage
ON linkage.user_id = users.user_id
WHERE linkage.linked_contact_id = 1
Get Users information
SELECT users.*,
linkage.*,
contact.user_id as contact_user_id,
contact.user_name AS contact_user_name
FROM users
INNER JOIN linkage ON linkage.user_id = users.user_id
INNER JOIN users AS contact ON linkage.linked_contact_id = contact.user_id
WHERE linkage.linked_contact_id = 1
Edit
Here Screenshot of Query Output
Sorry but I am not sure how to ask this question but I am working on a help desk application where I have tickets being created in one table. I also have another table that stores the users. My problem is with the tickets table, I have listed the user that created the ticket, the tech who will solve the ticket and a user that over sees the ticket. All three users reference the users table. So how do I can I query the tickets table and get all three users that reference the same table storing the users?
Table1: Tickets
1) Ticketnumber
2) EnteredBy User 100
3) Issue
4) FixedBy User 102
5) FixedByNotes
6) ResponsilbeUser User 103
Table2: Users
1) UserID
2) UserName
What I can do now is something like this:
Select Ticketnumber, EnteredBy, Issue, UserName FROM Tickets INNER JOIN Users
ON Tickets.EnteredBy = Users.UserID
Thanks Steve
You can extend current query to somewhat as follows:
Select Ticketnumber, Issue, Reporter.UserName, Developer.UserName, Manager.UserName FROM Tickets
INNER JOIN Users AS Reporter ON Tickets.EnteredBy = Reporter.UserID
INNER JOIN Users AS Developer ON Tickets.FixedBy = Developer.UserID
INNER JOIN Users AS Manager ON Tickets.ResponsibleUser = Manager.UserID
You need alias for joint tables if you want to get all names:
Select Ticketnumber, Issue, Informers.UserName, Fixers.UserName, Supervisors.UserName FROM Tickets
INNER JOIN Users Informers ON Tickets.EnteredBy = Users.UserID
INNER JOIN Users Fixers ON Tickets.FixedBy = Users.UserID
INNER JOIN Users Supervisors ON Ticket.ResponsibleUser = Users.UserID
WHERE...
Sorry as i am not able to understand your words, but if I assumed your need correctly.. just for a try this could help you..
if you need either of them i.e. all users who has either entered or fixed or saw an issue you can find by..
Select t.Ticketnumber, t.EnteredBy, t.Issue, u.UserID ,u.UserName FROM Tickets t
INNER JOIN Users u ON t.EnteredBy = u.UserID or t.FixedBy = u.UserID
or t.ResponsibleUser = u.UserID;
And If you need all users who has entered, fixed and saw an issue you can find by..
Select t.Ticketnumber, t.EnteredBy, t.Issue, u.UserID ,u.UserName FROM Tickets t
INNER JOIN Users u ON t.EnteredBy = u.UserID and t.FixedBy = u.UserID
and t.ResponsibleUser = u.UserID;
I am using a system I didn't create. The system has 3 main tables:
users, courses, and usergroups. I am using an extra table called coursehits.
It's a MySQL DB, 5.0. There aren't any relationships in the DB, so users are assigned to courses by simply adding an entry to usergroups (course_id and user_id) from the courses and users table. Likewise if they start a course an entry is made to coursehits.
I am trying to count the number of users in coursehits and usergroups for reporting data. So far I have the following which doesn't count correctly in one query but this doesn't count correctly, the results are much too high:
SELECT DISTINCT
c.course_name,
COUNT(ug.user_id) AS "Enrolled",
COUNT(ch.user_id) as "Started"
FROM courses c, usergroups ug, coursehits ch, users u
WHERE ch.user_id = u.id
AND ug.user_id = u.id
AND ug.course_id = c.id
AND ch.page_id != 4
GROUP BY 1
Before I was doing the following individually which does work:
SELECT DISTINCT c.course_name, COUNT(ug.user_id) AS "Enrolled"
FROM courses c, usergroups ug
WHERE ug.course_id = c.id
GROUP BY 1
Where as now I am trying to report the status of users for each course on one query, I hope that makes sense?!?
Try:
SELECT c.course_name,
COUNT(DISTINCT ug.user_id) AS "Enrolled",
COUNT(DISTINCT ch.user_id) as "Started"
FROM courses c
left join usergroups ug on ug.course_id = c.id
left join coursehits ch on ch.course_id = c.id and ch.page_id != 4
GROUP BY c.course_name