SQL Query - Multiple Joins on Same field - sql

I need assistance building this query where i need to select different values from same table but different Unique Keys.
To elaborate more ill provide the below example:
I have 2 tables:
Issues (IssueID, AuthorID_FK, AssigedID_FK, ... )
Users (UserID, User_Label, ... )
Both AuthorID_FK & AssigedID_FK are linked to table Users and i need to get in the same query result the User_Label for both.
Can you please assist?
Thanks,

SELECT a.IssueID, b.User_Label, c.User_Label FROM Issues a
INNER JOIN USERS b on a.AuthorID_FK = b.UserID
INNER JOIN USERS c on a.AssignedID_FK = c.UserID
something like that :) This should work in MS SQL Server

Well, this one should work too :)
SELECT IssueID, U.User_Label FROM Issues I
INNER JOIN Users U ON U.UserID = I.AuthorID_FK
UNION
SELECT IssueID, U.User_Label FROM Issues I
INNER JOIN Users U ON U.UserID = I.AssigedID_FK

Wont
SELECT a.IssueID, b.UserID
FROM Issues a
JOIN Users b ON (a.AuthorID_FK=b.UserID OR a.AssignedID_FK = b.UserID)
work?

You may want to try something like this
SELECT
issues.IssueID,
Authour.User_Label AS Author_Label,
Assigned.User_Label AS Assigned_user_Label
FROM
issues
INNER JOIN users AS Authour ON Authour.UserID = issues.AuthorID_FK
INNER JOIN users AS Assigned ON Assigned.UserID = issues.AssignedID_FK

Related

SQL Where on different table

SELECT * FROM student_mentor sm INNER JOIN users u
ON sm.student_id = u.user_id
WHERE sm.teacher_id = $teacher_id
Teacher_id being the session id,
I want to see all the students that have the same mentor.
Right now if I run this I just see all of the students twice, maybe one of you knows why?
My db scheme
You are not specifying on which columns you want to do the join, so you're getting a cross reference where all records are joined to all records.
You should do something like (not sure about your column names):
SELECT * FROM student_mentor sm INNER JOIN users u
ON sm.student_id = u.user_id
WHERE sm.teacher_id = $teacher_id

Access SQL LEFT JOIN not returning results

I have three tables: Comments, Users and CommentsHelpfulness.
Users can submit several comments, which are stored in the Comments table.
CommentsHelpfulness has three columns: UserID, CommentID and a "Helpful" Boolean. Every user can indicate for every comment if they find it useful, which will create an entry in the CommentsHelpfulness table.
I want a query that gives me all Comment IDs, with the name of the user that submitted it and shows whether the currently logged in user found it helpful, did not find it helpful or did not say anything about it. So the ID of a comment the current user did not express his opinion about should still be output, just without the helpful Boolean.
To me that sounds like it should be done like this using a left join:
SELECT Comments.ID, Users.Nom, CommentsHelpfulness.Helpful
FROM (Comments INNER JOIN Users
ON Comments.UserID = Users.ID)
LEFT JOIN CommentsHelpfulness
ON (CommentsHelpfulness.CommentID = Comments.ID
AND (CommentsHelpfulness.UserID = ?))
Unfortunately this does not output Comment IDs without an entry in the CommentsHelpfulness table. Why does this not work? Is it because of Access?
I think the issue is the inner join, not the left join.
Try removing that table:
SELECT c.ID, ch.Helpful
FROM Comments as c LEFT JOIN
CommentsHelpfulness as ch
ON ch.CommentID = c.ID AND
ch.UserID = ?
select c.id, c.Nom, d.Helpful from (
select a.ID, b.Nom from Comments a left join Users b
on a.UserID = b.ID) c left join CommentsHelpfulness d
on d.CommentID = c.ID;

SQL join two queries

I am a bit lost here. I would like to join these two queries into one to avoid two connections and simplify the code.
"SELECT uname FROM Projects WHERE id IN (SELECT MAX(id) FROM Projects)"
"SELECT name FROM Users WHERE username like"+"'"+ uname +"'"
Right now I am using two queries and taking the result of the first into the second one.
I am sure the two queries can become one but I do not know how to do it.
You can simply use = rather than LIKE since I you are not using pattern symbol such as %.
SELECT a.name
FROM Users a
INNER JOIN Projects b
ON a.username = b.uname
WHERE b.ID = (SELECT MAX(id) FROM Projects)
i think the following query will work:
SELECT name FROM Users WHERE username in
(SELECT uname FROM Projects WHERE id IN
(SELECT MAX(id) FROM Projects))
You may try like this using the INNER JOIN considering that both of your tables are linked through User_ID
SELECT u.name
FROM Users u INNER JOIN Projects p ON u.username = p.uname
WHERE p.ID = (SELECT MAX(id) FROM Projects)

Unable to Group on MSAccess SQL multiple search query

please can you help me before I go out of my mind. I've spent a while on this now and resorted to asking you helpful wonderful people. I have a search query:
SELECT Groups.GroupID,
Groups.GroupName,
( SELECT Sum(SiteRates.SiteMonthlySalesValue)
FROM SiteRates
WHERE InvoiceSites.SiteID = SiteRates.SiteID
) AS SumOfSiteRates,
( SELECT Count(InvoiceSites.SiteID)
FROM InvoiceSites
WHERE SiteRates.SiteID = InvoiceSites.SiteID
) AS CountOfSites
FROM (InvoiceSites
INNER JOIN (Groups
INNER JOIN SitesAndGroups
ON Groups.GroupID = SitesAndGroups.GroupID
) ON InvoiceSites.SiteID = SitesAndGroups.SiteID)
INNER JOIN SiteRates
ON InvoiceSites.SiteID = SiteRates.SiteID
GROUP BY Groups.GroupID
With the following table relationship
http://m-ls.co.uk/ExtFiles/SQL-Relationship.jpg
Without the GROUP BY entry I can get a list of the entries I want but it drills the results down by SiteID where instead I want to GROUP BY the GroupID. I know this is possible but lack the expertise to complete this.
Any help would be massively appreciated.
I think all you need to do is add groups.Name to the GROUP BY clause, however I would adopt for a slightly different approach and try to avoid the subqueries if possible. Since you have already joined to all the required tables you can just use normal aggregate functions:
SELECT Groups.GroupID,
Groups.GroupName,
SUM(SiteRates.SiteMonthlySalesValue) AS SumOfSiteRates,
COUNT(InvoiceSites.SiteID) AS CountOfSites
FROM (InvoiceSites
INNER JOIN (Groups
INNER JOIN SitesAndGroups
ON Groups.GroupID = SitesAndGroups.GroupID
) ON InvoiceSites.SiteID = SitesAndGroups.SiteID)
INNER JOIN SiteRates
ON InvoiceSites.SiteID = SiteRates.SiteID
GROUP BY Groups.GroupID, Groups.GroupName;
I think what you are looking for is something like the following:
SELECT Groups.GroupID, Groups.GroupName, SumResults.SiteID, SumResults.SumOfSiteRates, SumResults.CountOfSites
FROM Groups INNER JOIN
(
SELECT SitesAndGroups.SiteID, Sum(SiteRates.SiteMonthlySalesValue) AS SumOfSiteRates, Count(InvoiceSites.SiteID) AS CountOfSites
FROM SitesAndGroups INNER JOIN (InvoiceSites INNER JOIN SiteRates ON InvoiceSites.SiteID = SiteRates.SiteID) ON SitesAndGroups.SiteID = InvoiceSites.SiteID
GROUP BY SitesAndGroups.SiteID
) AS SumResults ON Groups.SiteID = SumResults.SiteID
This query will group your information based on the SiteID like you want. That query is referenced in the from statement linking to the Groups table to pull the group information that you want.

sql - How to have multiple select/from statements in one query

I'm trying to pull a report where each column is selecting from a specific table set. However, one of the columns needs to pull from a completely different table set and still be included in the same report. Of course, this doesn't work:
select u.first_name, ticket_work.time_spent
FROM tickets LEFT OUTER JOIN ticket_work ON ticket_work.ticket_id = tickets.id JOIN users u
(select count(tickets.id) FROM tickets JOIN users u)
where tickets.assigned_to = u.id
...
So just the part (select count(tickets.id) FROM tickets JOIN users u) needs to be selecting from the different table set but still be included in the report.
I'm a little confused by your question. Are you wanting to return the user, the count of tickets for that user, and the amount of time spent overall? If so, something like this should work:
select u.id, u.first_name,
SUM(tw.time_spent) summed_time_spent,
COUNT(DISTINCT t.id) count_tickets
FROM users u
LEFT JOIN tickets t
ON u.id = t.assigned_to
LEFT JOIN ticket_work tw
ON tw.ticket_id = t.id
GROUP BY u.id, u.first_name
Your questions is unclear, but just generally, it sounds like you're trying to join to a derived table (i.e., a query). In that case, do this:
SELECT...
FROM...
table_A A LEFT JOIN
(SELECT keyfield, valuefield FROM table_b WHERE ...) B
ON A.keyfield = B.keyfield
Does that make sense? To make a derived table, you put a query inside of parenthesis, give it an alias ('B' in this case), and then join it to your other tables as though it were a regular table.
Don't know about your table structure but you may use a sub query for such requirement
select u.first_name, ticket_work.time_spent,(select count(tickets.id) FROM tickets where ticket.id=ticket_work.ticket_id) as myCount
FROM tickets LEFT OUTER JOIN ticket_work ON ticket_work.ticket_id = tickets.id JOIN users u
where tickets.assigned_to = u.id