I am trying to calculate a percentile using the percentile_cont() function in PostgreSQL using common table expressions. The goal is find the top 1% of accounts regards to their balances (called amount here). My logic is to find the 99th percentile which will return those whose account balances are greater than 99% of their peers (and thus finding the 1 percenters)
Here is my query
--ranking subquery works fine
with ranking as(
select a.lname,sum(c.amount) as networth from customer a
inner join
account b on a.customerid=b.customerid
inner join
transaction c on b.accountid=c.accountid
group by a.lname order by sum(c.amount)
)
select lname, networth, percentile_cont(0.99) within group
order by networth over (partition by lname) from ranking ;
I keeping getting the following error.
ERROR: syntax error at or near "order"
LINE 2: ...ame, networth, percentile_cont(0.99) within group order by n..
I am thinking that perhaps I forgot a closing brace etc. but I can't seem to figure out where. I know it could be something with the order keyword but I am not sure what to do. Can you please help me to fix this error?
This tripped me up, too.
It turns out percentile_cont is not supported in postgres 9.3, only in 9.4+.
https://www.postgresql.org/docs/9.4/static/release-9-4.html
So you have to use something like this:
with ordered_purchases as (
select
price,
row_number() over (order by price) as row_id,
(select count(1) from purchases) as ct
from purchases
)
select avg(price) as median
from ordered_purchases
where row_id between ct/2.0 and ct/2.0 + 1
That query care of https://www.periscopedata.com/blog/medians-in-sql (section: "Median on Postgres")
You are missing the brackets in the within group (order by x) part.
Try this:
with ranking
as (
select a.lname,
sum(c.amount) as networth
from customer a
inner join account b on a.customerid = b.customerid
inner join transaction c on b.accountid = c.accountid
group by a.lname
order by networth
)
select lname,
networth,
percentile_cont(0.99) within group (
order by networth
) over (partition by lname)
from ranking;
I want to point out that you don't need a subquery for this:
select c.lname, sum(t.amount) as networth,
percentile_cont(0.99) within group (order by sum(t.amount)) over (partition by lname)
from customer c inner join
account a
on c.customerid = a.customerid inner join
transaction t
on a.accountid = t.accountid
group by c.lname
order by networth;
Also, when using table aliases (which should be always), table abbreviations are much easier to follow than arbitrary letters.
Related
I have two tables. One is Transactions and the other is Tickets. In Tickets I have the Ticket_Number,the name of the Category(Theater,Cinema,Concert), the Price of the Ticket. In Transactions I also have the Ticket_Number. What i want to do is to Get a SUM of money for each Category, and then with that data I want to Select the Category with the most money.
I already managed to get the SUM for each category but I am stuck here
SELECT category, SUM (Tickets.Price) AS Price
FROM Tickets,Transactions
WHERE Tickets.ticket_num=Transactions.ticket_num
GROUP BY Category
ORDER BY Price DESC;
I know i can add LIMIT 1 but I know it's not correct because 2 or more values can be the same
Using ROW_NUMBER to generate a sequence based on the sum of the price. Then, restrict to only the matching aggregated row with the highest total price.
WITH cte AS (
SELECT category, SUM(t1.Price) AS Price,
ROW_NUMBER() OVER (ORDER BY SUM(t1.Price) DESC) rn
FROM Tickets t1
INNER JOIN Transactions t2
ON t1.ticket_num = t2.ticket_num
GROUP BY Category
)
SELECT category, Price
FROM cte
WHERE rn = 1
ORDER BY Price DESC;
Note that if you want to capture all categories tied for the highest price, should a tie occur, then replace ROW_NUMBER in the above CTE with RANK, keeping everything else the same.
What you are looking for is a window function DENSE_RANK() which will handle ties properly.
RANK() will also work for your case, but if you would like to extend it to get TOP N places with ties (where N > 1), dense rank is the way to go.
SELECT Category, Price
FROM (
SELECT
Category,
SUM(ti.Price) AS Price,
DENSE_RANK() OVER (ORDER BY SUM(ti.Price) DESC) AS rnk
FROM Tickets ti
INNER JOIN Transactions tr ON
ti.ticket_num = tr.ticket_num
GROUP BY Category
) t
WHERE rnk = 1
I've also replaced the old style and not recommended joining of tables as comma separated list in FROM clause to a proper INNER JOIN clause and assigned aliases to tables.
You can use rank() to rank the sums of the prices, more expensive first.
SELECT category,
price
FROM (SELECT category,
sum(tickets.price) price,
rank() OVER (ORDER BY sum(tickets.price) DESC) r
FROM tickets
INNER JOIN transactions
ON transactions.ticket_num = tickets.ticket_num
GROUP BY category) x
WHERE r = 1;
I also took the liberty to rewrite your join from the ancient comma style to a modern, clearer version.
I'm trying to get the sum of the total time that was spent sending all emails within a campaign.
Because of the joins in my query I end up with the 'processing_time' column duplicated over many rows. So running sum(s.processing_time) as send_time will always over represent how long it took to run.
select
c.id,
c.sender,
c.subject,
count(*) as total_items,
count(distinct s.id) as sends,
sum(s.processing_time) as send_time,
from campaigns c
left join sends s on c.id = s.campaigns_id
left join opens o on s.id = o.sends_id
group by c.id;
I'd ideally like to do something like sum(s.processing_time when distinct s.id) but I can't quite work out how to achieve that.
I have made other attempts using case but I always run into the same issue, I need to get the distinct rows based on the ID column, but work with another column.
Since you want statistics related to distinct s.id as well as c.id, group by both columns. Collect the (intermediate) data that you need,
and use this table as the inner table in a nested sub-select query.
In the outer select, group by c.id alone.
Since the inner select groups by s.id, values which are unique per s.id will not get double-counted when you sum/group by c.id.
SELECT id
, sender
, subject
, sum(total_items) as total_items
, sum(sends) as sends
, sum(processing_time) as send_time
FROM (
SELECT
c.id
, s.id as sid
, count(*) as total_items
, 1 as sends
, s.processing_time
, c.sender
, c.subject
FROM campaigns c
LEFT JOIN sends s on c.id = s.campaigns_id
LEFT JOIN opens o on s.id = o.sends_id
GROUP BY c.id, c.sender, c.subject, s.processing_time, s.id) t
GROUP BY id, sender, subject
ORDER BY id
Since the final table includes sender and subject, you'll need to group by these columns as well to avoid an error such as:
ERROR: column "c.sender" must appear in the GROUP BY clause or be used in an aggregate function
LINE 14: , c.sender
I have a difficulty dealing with a SQL query. I use PostgreSQL.
The query says: Show the customers that have done at least an order that contains products from 3 different categories. The result will be 2 columns, CustomerID, and the amount of orders. I have written this code but I don't think it's correct.
select SalesOrderHeader.CustomerID,
count(SalesOrderHeader.SalesOrderID) AS amount_of_orders
from SalesOrderHeader
inner join SalesOrderDetail on
(SalesOrderHeader.SalesOrderID=SalesOrderDetail.SalesOrderID)
inner join Product on
(SalesOrderDetail.ProductID=Product.ProductID)
where SalesOrderDetail.SalesOrderDetailID in
(select DISTINCT count(ProductCategoryID)
from Product
group by ProductCategoryID
having count(DISTINCT ProductCategoryID)>=3)
group by SalesOrderHeader.CustomerID;
Here are the database tables needed for the query:
where SalesOrderDetail.SalesOrderDetailID in
(select DISTINCT count(ProductCategoryID)
Is never going to give you a result as an ID (SalesOrderDetailID) will never logically match a COUNT (count(ProductCategoryID)).
This should get you the output I think you want.
SELECT soh.CustomerID, COUNT(soh.SalesOrderID) AS amount_of_orders
FROM SalesOrderHeader soh
INNER JOIN SalesOrderDetail sod ON soh.SalesOrderID = sod.SalesOrderID
INNER JOIN Product p ON sod.ProductID = p.ProductID
HAVING COUNT(DISTINCT p.ProductCategoryID) >= 3
GROUP BY soh.CustomerID
Try this :
select CustomerID,count(*) as amount_of_order from
SalesOrder join
(
select SalesOrderID,count(distinct ProductCategoryID) CategoryCount
from SalesOrderDetail JOIN Product using (ProductId)
group by 1
) CatCount using (SalesOrderId)
group by 1
having bool_or(CategoryCount>=3) -- At least on CategoryCount>=3
I have a SQL statement that works as-is. I get an area name and the minimum value within that area. next, I need to add in a key so I can actually do something with the results. The key is necessary since names and values are unlikely to be unique.
select g.name, min(g.rndval) from
(
select p.rndval, a.name, p.id
from points p, areas a
where ST_WITHIN(p.geom, a.geom)
) AS g
group by g.name
When I add the Id field to the group by, the query returns multiple rows for each area, as expected since it's grouping by the name and id combination, and the results are no longer what I need. How should I add in the id field (p.id in the inner select)?
You can try:
WITH cte AS
( select p.rndval, a.name, p.id
from points p, areas a
where ST_WITHIN(p.geom, a.geom)
), cte_aggregated AS
(
SELECT name, min(rndval) AS min_value
FROM cte
GROUP BY name
)
SELECT DISTINCT c.rndval, c.name, c.id
FROM cte c
JOIN cte_aggregated ca
ON c.rndval = ca.min_value
AND c.name = ca.name;
You can solve this quite elegantly with a window function:
select name, rndval as min, id
from (
select a.name, p.rndval, p.id, rank() over (partition by a.name order by p.rndval) as rnk
from points p
join areas a on ST_Within(p.geom, a.geom)) as g
where rnk = 1;
I'm having some trouble trying to get Microsoft Access 2007 to accept my SQL query but it keeps throwing syntax errors at me that don't help me correct the problem.
I have two tables, let's call them Customers and Orders for ease.
I need some customer details, but also a few details from the most recent order. I currently have a query like this:
SELECT c.ID, c.Name, c.Address, o.ID, o.Date, o.TotalPrice
FROM Customers c
INNER JOIN Orders o
ON c.ID = o.CustomerID
AND o.ID = (SELECT TOP 1 ID FROM Orders WHERE CustomerID = c.ID ORDER BY Date DESC)
To me, it appears valid, but Access keeps throwing 'syntax error's at me and when I hit OK, it selects a piece of the SQL text that doesn't even relate to it.
If I take the extra SELECT clause out it works but is obviously not what I need.
Any ideas?
You cannot use AND in that way in MS Access, change it to WHERE. In addition, you have two reserved words in your column (field) names - Name, Date. These should be enclosed in square brackets when not prefixed by a table name or alias, or better, renamed.
SELECT c.ID, c.Name, c.Address, o.ID, o.Date, o.TotalPrice
FROM Customers c
INNER JOIN Orders o
ON c.ID = o.CustomerID
WHERE o.ID = (
SELECT TOP 1 ID FROM Orders
WHERE CustomerID = c.ID ORDER BY [Date] DESC)
I worked out how to do it in Microsoft Access. You INNER JOIN on a pre-sorted sub-query. That way you don't have to do multiple ON conditions which aren't supported.
SELECT c.ID, c.Name, c.Address, o.OrderNo, o.OrderDate, o.TotalPrice
FROM Customers c
INNER JOIN (SELECT * FROM Orders ORDER BY OrderDate DESC) o
ON c.ID = o.CustomerID
How efficient this is another story, but it works...