I am quite new to SQL, have been learning for ~3 weeks, and have taken a liking to it. Hoping to polish up my skills before beginning to apply to Data Analyst roles.
I've been working with a dummy dvd-rental database and have found myself unable to solve a challenge given to me by a peer. The question was: "what is the most expensive rental for the 4th customer?"
We can see in picture, that based on the nth_customer column, Terrance Roush is the 4th ever customer (he's the 4th ever person to pay). But the issue is that the nth_customer column is actually reporting back the nth order and continues counting to infinity. So the next time Terrance shows up, the nth_customer column will not show '4' (which is what I was hoping to achieve).
Would appreciate any feedback on how to solve this. Thank you in advance.
If "the fourth customer" means the customer who did the fourth rental, you can break the problem down into two - finding that fourth customer, and finding their most expensive rental. Something like this:
SELECT *
FROM payment
WHERE customer_id = (
SELECT customer_id
FROM payment
ORDER BY payment_date
LIMIT 1 OFFSET 3
)
ORDER BY amount DESC
LIMIT 1;
Here I'm finding the ID of the fourth customer in the subquery, using a LIMIT & OFFSET to get just the one record I want. Then in the outer query I'm simply ordering all of that customer's records and taking the one with the biggest amount.
Related
edited as requested:
My apologies. I've been dealing with this a bit and it's well and truly in my head, but not for the reader.
We have multiple records in table A which have multiple entries in the Period column. Say it's like a football schedule. Teams will have multiple dates/times in the Period column.
When we run query:
We want records selected for the most recent games only.
We don't want the earlier games.
We don't want the games "scheduled" and not yet played.
"Last game played" i.e. Period for teams are often on different days.
Table like:
Team Period
Reds 2021020508:00
Reds 2021011107:00
City 2021030507:00
Reds 2021032607:00
City 2021041607:00
Reds 2021050707:00
When I run query, I want to see the records for last game played regardless of date. So if I run the query on 27 Mar 2021, I want:
City 2021030507:00
Reds 2021032607:00
Keep in mind I used the above as an easily understandable example. In my case I have 1000s of "Teams" each of which may have 100+ different date entries in the Period column and I would like the solution to be applicable regardless of number of records, dates, or when the query is run.
What can I do?
Thanks!
So this gives you your desired output using the sample data, does it fulfil your requirement?
create table x (Team varchar(10), period varchar(20))
insert into x values
('Reds','2021020508:00'),
('Reds','2021011107:00'),
('City','2021030507:00'),
('Reds','2021032607:00'),
('City','2021041607:00'),
('Reds','2021050707:00')
select Team, Max(period) LastPeriod
from x
where period <=Format(GetDate(), 'yyyyMMddhh:mm')
group by Team
The string-formatted date you have order by text, so I think this would work
SELECT TOP 2 *
FROM tableA
WHERE period = FORMAT( GETDATE(), 'yyyyMMddhh:mm' )
ORDER BY period
Perhaps you want:
where period = (select max(t2.period) from t t2)
This returns all rows with the last period in the table.
I desperately need some help from your brains to solve one SQL problem I have now.
I have a very simple table made of two columns: Client # and Purchasing Date.
I want to add one more column to show how many days have passed since the previous Purchasing Date per each Client #. Below is my current query to create the starting table.
select client_id, purchasing_date
from sales.data
The result looks like this (apparently, I need more reputation to post images):
https://imgur.com/a/IP1ot
The highlighted column on the right is the column I want to create.
Basically, that shows the number of days elapsed since the previous purchasing date of each Client #. For the first purchase of each Client, it will be just 0.
I'm not sure if I have explained enough to help you guys produce solutions - if you have any questions, please let me know.
Thanks!
Use lag():
select client_id, purchasing_date,
(purchasing_date -
lag(purchasing_date, 1, purchasing_date) over (partition by client_id
order by purchasing_date
)
) as day_diff
from sales.data
I'm working with a list of engagement scores for each company.
SELECT pel.companyProfileID, pel.engagementScore, pel.createTimestamp
FROM partnerEngagementLog pel
A snippet of results for one company:
I'm trying to produce a cohort analysis table with:
A single row for each companyProfileID.
Columns for each engagementScore by latest, second latest, etc.
The issue is that time between timestamps varies and I'm having trouble figuring out how to select properly. Put another way, what I need is columns for "last score per companyID", "second-to-last", "third-to-last", etc. that are based on absolute row positioning and not date range.
Any help would be greatly appreciated, still learning SQL on the side as I develop my business.
hello i want to write a query which tells me the great number of tweets collect on a particular day like my question is
"date during your collection period saw the greatest number of matching tweets"
i have collected data from tweetcatcher but didnt know which query i use
Not much to go on, but based on your comment
SELECT date, Tweets=count(*) FROM Course GROUP BY date Order by 2 Desc
You could also add Select Top 1 ... if you want only one record.
Good day. I'm having a hard time figuring out how to do this:
SELECT P.GrossSalary, S.Contribution FROM Payroll AS P, SSSChart AS S WHERE
P.GrossSalary >= S.RangeStart AND P.GrossSalary <= S.RangeEnd;
I need the corresponding contribution amount from SSSChart table where the Gross Salary is between the Start and End range.
The problem is it will work on the first found matched record from Payroll table but the searching from the SSSChart table will not start from the top again for the next Payroll record, instead, will continue the search after the found record from the previous Payroll record. I tried several SQL commands but found no luck. All the help will be appreciated. (Doing this for my payroll system practice)
Do you want to query the entire Payroll table and find the corresponding contribution value from the SSSChart table for each result? Consider trying something along the lines of:
SELECT
P.GrossSalary, S.Contribution
FROM
Payroll as P
LEFT JOIN
SSSChart as S ON P.GrossSalary >= S.RangeStart AND P.GrossSalary <= S.RangeEnd
WHERE
1;
This is assuming each GrossSalary only belongs to exactly one SSSChart range.