This query (minimal reproducible example):
WITH t as (
SELECT 3 id, 2 price, 0 amount
)
SELECT
CASE WHEN amount > 0 THEN
SUM(price / amount)
ELSE
price
END u_price
FROM t
GROUP BY id, price, amount
on PostgreSQL 9.4 throws
division by zero
Without the SUM it works.
How is this possible?
I liked this question and I turned for help to these tough guys :
The planner is guilty:
A CASE cannot prevent evaluation of an aggregate expression contained
within it, because aggregate expressions are computed before other
expressions in a SELECT list or HAVING clause are considered
More details at https://www.postgresql.org/docs/10/static/sql-expressions.html#SYNTAX-EXPRESS-EVAL
I cannot figure the "why" part out, but here is a workaround...
WITH t as (
SELECT 3 id, 2 price, 0 amount
)
SELECT SUM(price / case when amount = 0 then 1 else amount end) u_cena
FROM t
GROUP BY id, price, amount
OR: you can use the following and avoid the "case"
SELECT SUM(price / power(amount,sign(amount))) u_cena
FROM t
GROUP BY id, price, amount
Related
I try to write a select query in my PostgreSQL database table containing history of customers settlement. The query result should show sum of amounts based only of customers, who are debtors (sum of all invoices amounts of each customer is gteater than zero). In attached example (picture below) - when we take detailed settlement history from date: 10.06.2021, You can see that invoices total amount of customer A is plus (+) 190000 so this customers sum should be taken to total sum. From the other side, invoices amount sum of customer B is minus (-)266000 so this one is not debtor and should be skipped. I try to make a sum containing only positive partial sums of each customer divided by customer status as shown on the screen below (Expected result).
I tried query like this:
select s.*, s.active+s.inactive total from
(select to_char(date_trunc('month', debt_date),'YYYY-MM'),
greatest(sum(case when t.status = 'Active' then t.amount::numeric else 0 end),0) active,
greatest(sum(case when t.status = 'Inactive' then t.amount::numeric else 0 end),0) inactive
from customers_settlement t
group by 1) s order by 1;
but it didn't work - manual calculation in Excel gave different results than the query. I guess that there is something missing like:
over (partition by customer)
I believe that professionals like You, will be able to help me quickly. Thank You in advance!
I am not totally certain if that is what you want, but you could first group by month and customer, then eliminate negative results, then sum again:
SELECT m,
sum(active) AS "sum(Active)",
sum(inactive) AS "sum(Inactive)",
sum(active) + sum(inactive) AS "sum(Total)"
FROM (SELECT to_char(date_trunc('month', debt_date),'YYYY-MM') AS m,
greatest(sum(t.amount) FILTER (WHERE t.status = 'Active'), 0) AS active,
greatest(sum(t.amount) FILTER (WHERE t.status = 'Inactive'), 0) AS inactive
FROM customers_settlement AS t
GROUP BY m, customer) AS subq
GROUP BY m;
I have the following sample table
And the output should be the first date (for each id) when cum_rev reaches the 100 mark.
I tried the following, because I taught with group bz trick and the where condition i will only get the first occurrence of value higher than 100.
SELECT id
,pd
,cum_rev
FROM (
SELECT id
,pd
,rev
,SUM(rev) OVER (
PARTITION BY id
ORDER BY pd
) AS cum_rev
FROM tab1
)
WHERE cum_rev >= 100
GROUP BY id
But it is not working, and I get the following error. And also when I add an alias is not helping
ERROR: subquery in FROM must have an alias LINE 4: FROM (
^ HINT: For example, FROM (SELECT ...) [AS] foo.
So the desired output is:
2 2015-04-02 135.70
3 2015-07-03 102.36
Do I need another approach? Can anyone help?
Thanks
demo:db<>fiddle
SELECT
id, total
FROM (
SELECT
*,
SUM(rev) OVER (PARTITION BY id ORDER BY pd) - rev as prev_total,
SUM(rev) OVER (PARTITION BY id ORDER BY pd) as total
FROM tab1
) s
WHERE total >= 100 AND prev_total < 100
You can use the cumulative SUM() window function for each id group (partition). To find the first which goes over a threshold you need to check the previous value for being under the threshold while the current one meets it.
PS: You got the error because your subquery is missing an alias. In my example its just s
I want to create a pivot table view showing month on month sum of bookings for every travel_mode.
Table bookings:
timestamp
, bookings
, provider_id
Table providers:
provider_id
, travel_mode
Pivot table function and crosstab functions are not to be used to do this. So I am trying to use JOIN and CASE. Following is the query:
SELECT b.month,
(CASE WHEN p.travel_mode=train then b.amount end)train,
(CASE WHEN p.travel_mode=bus then b.amount end)bus,
(CASE WHEN p.travel_mode=air then b.amount end)air
FROM
(SELECT to_char(date_,month) as month, travel_mode, sum(bookings) as amount
from bookings as b
join providers as p
on b.provider_id=p.provider_id
group by b.month, p.travel_mode)
group by b.month;
However I am getting an error which says:
subquery in FROM must have an alias LINE 6:
And when I add an alias it throws an error saying:
column p.travel_mode must appear in the GROUP BY clause or be used in an aggregate function
LINE 2:
The final result should be something like this
Month Air Bus Train
01 Amount(air) Amount(Bus) Amount(train)
I have a feeling it is a minor error somewhere but I am unable to figure it out at all.
P.S. I had to remove all quotations in the question as it was not allowing me to post this. But those are being taken care of in the actual query.
Multiple problems. The missing table alias is just one of them. This query should work:
SELECT month
, sum(CASE WHEN travel_mode = 'train' THEN amount END) AS train
, sum(CASE WHEN travel_mode = 'bus' THEN amount END) AS bus
, sum(CASE WHEN travel_mode = 'air' THEN amount END) AS air
FROM (
SELECT to_char(timestamp, 'MM') AS month, travel_mode, sum(bookings) AS amount
FROM bookings b
JOIN providers p USING (provider_id)
GROUP BY month, p.travel_mode
) sub
GROUP BY month;
Missing single quotes for string literals. (You seem to have removed those being under the wrong impression you couldn't post quotations.)
Missing table alias for the subquery - just like the 1st error message says.
In the outer query, table names (or aliases) of underlying tables in the subquery are not visible. Only the table alias of the subquery is. Since there is only one subquery, you don't need table-qualification at all there.
month is an output column name (not in the underlying table), so the table qualification b.month was wrong, too.
You seem to want 2-digit numbers for months. Use the template pattern 'MM' instead of 'month' with to_char().
The aggregation in the outer query does not work like you had it - just like your 2nd error message says. You have to wrap the outer CASE expression in a aggregate function. You might as well use min() or max() in this case, because there are never more than one rows after the subquery.
Still unclear where date_ is coming from? You mean timestamp? (which is not a good identifier).
But you don't need the subquery to begin with and can simplify to:
SELECT to_char(timestamp, 'MM') AS month
, sum(CASE WHEN p.travel_mode = 'train' THEN b.bookings END) AS train
, sum(CASE WHEN p.travel_mode = 'bus' THEN b.bookings END) AS bus
, sum(CASE WHEN p.travel_mode = 'air' THEN b.bookings END) AS air
FROM bookings b
JOIN providers p USING (provider_id)
GROUP BY 1;
For best performance you should still use crosstab(), though:
PostgreSQL Crosstab Query
You have to name the subquery as the error message says:
SELECT b.month,
(CASE WHEN p.travel_mode=train then b.amount end)train,
(CASE WHEN p.travel_mode=bus then b.amount end)bus,
(CASE WHEN p.travel_mode=air then b.amount end)air
FROM
(SELECT to_char(date_,month) as month, travel_mode, sum(bookings) as amount
from bookings as b
join providers as p
on b.provider_id=p.provider_id
group by b.month, p.travel_mode)
**as foo** group by b.month;
Remove the stars to make it work.
I am trying to find out the number of users who have scored an average of 80 or higher. I am using Having in my query but it is not returning the count of number of rows.
The Schema looks like:
Results
user
test_no
question_no
score
My Query:
SELECT "user" FROM results WHERE (score >0) GROUP BY "user"
HAVING (sum(score) / count(distinct(test_no))) >= 80;
I get:
user
2
4
8
(3 rows)
Instead I would like to get 3 (number of rows) as the output. If I do count("user"), I get the count of number of tests for each user.
I understand this is related to use Group By but I need it for my Having clause. Any suggestions how I can do this is appreciated.
Update: Here is some sample data: http://pastebin.com/k1nH5Wzh (-1 means unanswered)
Thanks!
The query you found is good. Some minor simplifications:
SELECT count(*) AS ct
FROM (
SELECT 1
FROM result
WHERE score > 0
GROUP BY user_id
HAVING (sum(score) / count(DISTINCT test_no)) >= 80
) sub
DISTINCT does not require parentheses.
You can SELECT a constant value in the subquery. The value is irrelevant, since you are only going to count the rows. Slightly shorter and cheaper.
Don't use the reserved word user as column name. That's asking for trouble. I am using user_id instead.
I am not sure if this is an efficient way to do it but this seems to be working.
SELECT COUNT(*) FROM
(SELECT "user" FROM results WHERE (score >0) GROUP BY "user"
HAVING (sum(score) / count(distinct(test_no))) >= 80)) q1;
i am trying to run an export on a system that only allows t-sql. i know enough of php to make a foreach loop, but i don't know enough of t-sql to generate multiple rows for a given quantity.
i need a result to make a list of items with "1 of 4" like data included in the result
given a table like
orderid, product, quantity
1000,ball,3
1001,bike,4
1002,hat,2
how do i get a select query result like:
orderid, item_num, total_items,
product
1000,1,3,ball
1000,2,3,ball
1000,3,3,ball
1001,1,4,bike
1001,2,4,bike
1001,3,4,bike
1001,4,4,bike
1002,1,2,hat
1002,2,2,hat
You can do this with the aid of an auxiliary numbers table.
;WITH T(orderid, product, quantity) AS
(
select 1000,'ball',3 union all
select 1001,'bike',4 union all
select 1002,'hat',2
)
SELECT orderid, number as item_num, quantity as total_items, product
FROM T
JOIN master..spt_values on number> 0 and number <= quantity
where type='P'
NB: The code above uses the master..spt_values table - this is just for demo purposes I suggest you create your own tally table using one of the techniques here.
If you are on SQL Server 2005 or later version, then you can try a recursive CTE instead of a tally table.
;WITH CTE AS
(
SELECT orderid, 1 item_num, product, quantity
FROM YourTable
UNION ALL
SELECT orderid, item_num+1, product, quantity
FROM CTE
WHERE item_num < quantity
)
SELECT *
FROM CTE
OPTION (MAXRECURSION 0)
I'm not on a computer with a database engine where I can test this, so let me know how it goes.
Well, IF you know the maximum value for the # of products for any product (and it's not too big, say 4), you can:
Create a helper table called Nums containing 1 integer column n, with rows containing 1,2,3,4
Run
SELECT * from Your_table, Nums
WHERE Nums.n <= Your_table.quantity