I have a table called 'games' that has a column in it called 'week'. I am trying to find a single query that will give me the maximum value for 'week' along with a count of how many rows in that table have the maximum value for 'week'. I could split it up into two queries:
SELECT MAX(week) FROM games
// store value in a variable $maxWeek
SELECT COUNT(1) FROM games WHERE week = $maxWeek
// store that result in a variable
Is there a way to do this all in one query?
SELECT week, count(*) FROM games GROUP BY week ORDER BY week DESC LIMIT 1;
or
SELECT week, count(*) FROM games WHERE week = (SELECT max(week) FROM games) GROUP BY week;
(may be faster)
Related
In my structure I have the following, I would like to keep (yellow) the most recent dates and delete the remaining? I don't necessary know the most recent date (ie 17/4/2021 and 10/2/2021 in my example) for each stock_id but I know I want to keep only the two most recent items.
Is that possible?
Thank you
Note: this assumes that dates do not repeat within each stock_id group in your table, so top two dates are always unique.
You can assign rank to each row within stock_id after ordering by date and delete rows where rank is greater than 2.
DELETE FROM mytable
WHERE (stock_id, date) NOT IN (
SELECT
stock_id,
date
FROM (
SELECT
stock_id,
date,
row_number() over (partition by stock_id order by date desc) as rank
FROM mytable
) ranks
WHERE rank <= 2
)
I am trying to estimate the time of a new order from repeat customers by finding the time difference between the most recent order and the second most recent order, and then adding that difference to the most recent order.
I have been trying limit and offset, but this returns a blanket date for every row. I am thinking I need to do a lateral join, but not sure how to implement it correctly. When I try to do it, I receive no output.
select public.orders.customer_id,
max(public.orders.created_at) as last_order_date,
(select created_at from public.orders group by created_at order by created_at desc limit 1 offset 1) as second_last
from public.orders
inner join
(select
customer_id, count(*)
from public.orders
where status = 'fulfilled'
group by public.orders.customer_id
having count(customer_id) >1) repeat_customers
on public.orders.customer_id = repeat_customers.customer_id
group by public.orders.customer_id;
I wanted the second_last field to be populated by the second most recent date for each customer_id, but the output is the second most recent date for the entire table, resulting in the same date for every entry.
For your second_last column you're not limiting it per customer, it will indeed find the max of everything just like the results you've seen. See the WHERE clause in the example below which should solve this:
(SELECT
created_at
FROM
public.orders po
WHERE
po.customer_id = customer_id
ORDER BY
created_at
LIMIT 1 OFFSET 1) AS second_last
I've also aliased the table because I wasn't sure if it would complain about ambiguity since the same table is mentioned in the main select.
I am using Oracle's PSQuery tool so I do not have access to the actual code. I would like to generate a list of students with their maximum dropped course . However, if the student has more than one dropped course on the same max date, I want to return the one with the max deadline date. So, all max drop dates with duplicates narrowed down further by max deadline date.
SELECT s.studentid, s.name, MAX(s.date), (s.deadlineDate), MAX(d.droppedCourse) AS droppedCourse
FROM Student s
JOIN DeadlineDate d ON s.studentid = d.studentid
GROUP BY s.studentid, s.name, s.date
HAVING MAX(d.DeadlineDate);
How to get the total count for particular date by selecting different dates.
For Example:
Record contains from '2014-04-01' to till date. Each date contains multiple records with different IST time.
How to get the total count from each date?
depending on your table structure and result you want, Query should look somewhat like this
SELECT DATE(date_column), COUNT(*)
FROM tablename
WHERE date_column IN (your_date_list)
GROUP BY date(date_column);
Have a look at the following sql (I have not tested)
SELECT date_column, COUNT(*)
FROM tablename
WHERE date_column BETWEEN date_column AND current_date
GROUP BY to_date(date_column::text,'YYYY-MM-DD')
I need to sum values that are + 2 months or within a quarter period (related date table)
is there a way to use dense rank to partition those periods (custom periods)?
select
FiscalMonth
,Value
from table
The sql will have to do the following:
Join the value table and the period table
Include the period in the select list and sum the value, grouping by the period
i.e
select b.period, sum(a.value)
from table a
inner join period b on a.FiscalMonth between b.StartMonth and b.EndMonth
group by b.period
Note: The join condition will have to be modified based on what data you actually have in the period table.
Hope this helps
Well, If you need value from an X interval, by month you could use something like:
SELECT *
FROM yourTable
MONTH(some_date) = MONTH(CURRENT_DATE - INTERVAL 1 MONTH) //Could be X interval!
This is an example (which show the results of the previous month, from the actual one). Just trying to write that it is possible to massage the query in functions on intervals.
Of course, you could use the SUMcommand for the adding.