Select from table join select in Visual FoxPro - join

I want to get Users' info with their last dates of login.
select * from Users as UU
inner join
(select user_id, max(d_login) from Logins group by user_id) as LL
on UU.user_id = LL.user_id
Join doesn't work in VFP. We can't join table to query here?

VFP need to use ALLTRIM() in join, otherwise comparing 2 values could result undesirable data. your code should be like this
select * from Users as UU
inner join
(select user_id, max(d_login) from Logins group by
user_id) as LL
on ALLT(UU.user_id) == ALLT(LL.user_id)

Assuming you have normalised User_ID as primary key in both tables i.e. Users and Logins and have same Field Type and Field Length. I created the tables users and Logins and tested this query with a sample data and it worked smoothly and gave exact results.
select
Users.User_id,
Users.Cell1,
Users.Name,
max(d_login)
from Logins, users
WHERE users.user_id = logins.user_id
GROUP BY
Users.user_id, Users.Cell1, Users.Name, Logins

Related

How to fix DF-JOIN-002 Error in Azure Data Factory (Only two Join conditions allowed)

I have a data flow with a Union on two tables then joining the results of the Union to another table. I keep receiving the following error when I try debugging the pipeline or previewing the data.
DF-JOIN-002 at Join 'Join1'(Line 40/Col 26): Only 2 join condition(s) allowed
I'm basically trying to build a pipeline to automate this query:
SELECT DISTINCT k.acct_id, s.Id, Email, FirstName, LastName FROM table_3 s
INNER JOIN
( (SELECT acct_id, event_date FROM table_1)
UNION (SELECT acct_id, event_date FROM table_2)) k
ON k.acct_id = s.Archtics_acct_id__c
WHERE event_date = 'xxxx-xx-xx'
enter image description here
I figured it out after some time. I had to delete the Join activity and add it again. It was still linked to another source. Even though only two sources were selected in the join settings

SQL Join issue with 3 tables and a subquery

Tables Involved:
account, user, service, accesshist
I want to include all records in the account table, and only the data from the other tables when it exists.
Count from account: 5064
rows returned from query below: 4915
select u.last_name, u.first_name, a.username, ll.mxlogin, si.servicename, a.islockedout
from account a
join service si on a.serviceid = si.serviceid
left outer join user u on u.loginid = a.username
left outer join(select max(loginattemptdate) as MxLogin, usernameattempted from accesshist where isloginsuccessful = 1
group by usernameattempted) ll
on a.username = ll.usernameattempted
where a.isenabled = 1
order by ll.mxlogin, u.last_name
I've narrowed it down that the subquery join is the part causing the number of rows to be reduced, but I am unsure how to correct it. Any insight is greatly appreciated!
Have you tried changing the first join to a left outer join?
select u.last_name, u.first_name, a.username, ll.mxlogin, si.servicename, a.islockedout
from account a
left outer join service si on a.serviceid = si.serviceid

Optimizing SQL query using JOIN instead of NOT IN

I have a sql query that I'd like to optimize. I'm not the designer of the database, so I have no way of altering structure, indexes or stored procedures.
I have a table that consists of invoices (called faktura) and each invoice has a unique invoice id. If we have to cancel the invoice a secondary invoice is created in the same table but with a field ("modpartfakturaid") referring to the original invoice id.
Example of faktura table:
invoice 1: Id=152549, modpartfakturaid=null
invoice 2: Id=152592, modpartfakturaid=152549
We also have a table called "BHLFORLINIE" which consists of services rendered to the customer. Some of the services have already been invoiced and match a record in the invoice (FAKTURA) table.
What I'd like to do is get a list of all services that either does not have an invoice yet or does not have an invoice that's been cancelled.
What I'm doing now is this:
`SELECT
dbo.BHLFORLINIE.LeveringsDato AS treatmentDate,
dbo.PatientView.Navn AS patientName,
dbo.PatientView.CPRNR AS patientCPR
FROM
dbo.BHLFORLINIE
INNER JOIN dbo.BHLFORLOEB
ON dbo.BHLFORLOEB.BhlForloebID = dbo.BHLFORLINIE.BhlForloebID
INNER JOIN dbo.PatientView
ON dbo.PatientView.PersonID = dbo.BHLFORLOEB.PersonID
INNER JOIN dbo.HENVISNING
ON dbo.HENVISNING.BhlForloebID = dbo.BHLFORLOEB.BhlForloebID
LEFT JOIN dbo.FAKTURA
ON dbo.BHLFORLINIE.FakturaId = FAKTURA.FakturaId
WHERE
(dbo.BHLFORLINIE.LeveringsDato >= '2017-01-01' OR dbo.BHLFORLINIE.FakturaId IS NULL) AND
dbo.BHLFORLINIE.ProduktNr IN (110,111,112,113,8050,4001,4002,4003,4004,4005,4006,4007,4008,4009,6001,6002,6003,6004,6005,6006,6007,6008,7001,7002,7003,7004,7005,7006,7007,7008) AND
((dbo.FAKTURA.FakturaType = 0 AND
dbo.FAKTURA.FakturaID NOT IN (
SELECT FAKTURA.ModpartFakturaID FROM FAKTURA WHERE FAKTURA.ModpartFakturaID IS NOT NULL
)) OR
dbo.FAKTURA.FakturaType IS NULL)
GROUP BY
dbo.PatientView.CPRNR,
dbo.PatientView.Navn,
dbo.BHLFORLINIE.LeveringsDato`
Is there a smarter way of doing this? Right now the added the query performs three times slower because of the "not in" subquery.
Any help is much appreciated!
Peter
You can use an outer join and check for null values to find non matches
SELECT customer.name, invoice.id
FROM invoices i
INNER JOIN customer ON i.customerId = customer.customerId
LEFT OUTER JOIN invoices i2 ON i.invoiceId = i2.cancelInvoiceId
WHERE i2.invoiceId IS NULL

Order by foreign key in activerecord: without a join?

I want to expand this question.
order by foreign key in activerecord
I'm trying to order a set of records based on a value in a really large table.
When I use join, it brings all the "other" records data into the objects.. As join should..
#table users 30+ columns
#table bids 5 columns
record = Bid.find(:all,:joins=>:users, :order=>'users.ranking DESC' ).first
Now record holds 35 fields..
Is there a way to do this without the join?
Here's my thinking..
With the join I get this query
SELECT * FROM "bids"
left join users on runner_id = users.id
ORDER BY ranking LIMIT 1
Now I can add a select to the code so I don't get the full user table, but putting a select in a scope is dangerous IMHO.
When I write sql by hand.
SELECT * FROM bids
order by (select users.ranking from users where users.id = runner_id) DESC
limit 1
I believe this is a faster query, based on the "explain" it seems simpler.
More important than speed though is that the second method doesn't have the 30 extra fields.
If I build in a custom select inside the scope, it could explode other searches on the object if they too have custom selects (there can be only one)
What you would like to achieve in active record writing is something along
SELECT b.* from bids b inner join users u on u.id=b.user_id order by u.ranking desc
In active record i would write such as:
Bids.joins("inner join users u on bids.user_id=u.id").order("u.ranking desc")
I think it's the only to make a join without fetching all attributes from the user models.

Selecting distinct through join

We have 2 tables: users and statuses
The status table has a user_id, status and occured_on. The status is either 'removed' or 'added' and occured_on is the date the user was removed or added.
I need the current added users. That is, all the (distinct) users whose newest status record is 'added'.
I'm using Rails, and have tried:
User
.joins(:statuses)
.where('statuses.status = ?', 'added')
.order('statuses.occured_on DESC')
.uniq
Which translates to the SQL:
SELECT DISTINCT users.*
FROM users
INNER JOIN statuses
ON statuses.user_id = users.id
WHERE statuses.status = 'added'
ORDER BY statuses.occured_on DESC
That gives me the error:
PG::Error: ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list
LINE 1: ...statuses.status = 'added') ORDER BY statuses.oc...
I'd be happy knowing either the Rails code that would work or the straight SQL.
Also, I'd prefer no sub-selects if possible.
Concider the following database schema change:
StatusTable:
StatusId
Status
UserId
ActiveFrom
ActiveTo
Afterwards you can add additional checks such as:
CONSTRAINT chk_from_to CHECK (ActiveFrom <= ActiveTo)
Then your query would look something like:
SELECT users.*
FROM users
JOIN statuses ON UserId = users.user_id AND ActiveFrom < CURRENT_TIMESTAMP AND ActiveTo > CURRENT_TIMESTAMP
WHERE statuses.Status = 'active'
With such structure you might need to change the way you change statuses, but from my own experience, this structure is much more flexible, and easier to query.
SELECT * FROM users INNER JOIN statuses ON users.id=statuses.user_id WHERE statuses.status='added' ORDER BY statuses.occured_on
After clarification, I don't think the schema is well designed for your goal. Can you clarify why you want the status change history contained in that table? My general approach to this would be that active users should be contained in a table called projects_users, containing project_id, user_id. When they are "removed" they should be removed from that table. Logs of the actions - adding and remove users from projects - should be stored in a separate table.
There's no good way that I'm aware of to write this query given your current design. Even if you fixed the errors, this runs error free in MySQL (which is exactly what you have)
SELECT DISTINCT `users`.* FROM `users`
INNER JOIN `projects_users`
ON `users`.`id`=`projects_users`.`user_id`
WHERE `status`='added'
ORDER BY `projects_users`.`occured_on` DESC
it still won't get you the correct results. The ORDER BY clause will just get you the most recent change to "added", it won't guarantee there is not a more recent "removed" action. To do that you'd need to compare the date of each most recent added record to the date of the most recent removed record, for each user, a nightmare.

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