I need someone who can explain me about "group function is not allowed here" because I don't understand it and I would like to understand it.
I have to get the product name and the unit price of the products that have a price above the average
I initially tried to use this, but oracle quickly told me that it was wrong.
SELECT productname,unitprice
FROM products
WHERE unitprice>(AVG(unitprice));
search for information and found that I could get it this way:
SELECT productname,unitprice FROM products
WHERE unitprice > (SELECT AVG(unitprice) FROM products);
What I want to know is why do you put two select?
What does group function is not allowed here mean?
More than once I have encountered this error and I would like to be able to understand what to do when it appears
Thank you very much for your time
The phrase "group function not allowed here" is referring to anything that is in some way an "aggregation" of data, eg SUM, MIN, MAX, etc et. These functions must operate on a set of rows, and to operate on a set of rows you need to do a SELECT statement. (I'm leaving out UPDATE/DELETE here)
If this was not the case, you would end up with ambiguities, for example, lets say we allowed this:
select *
from products
where region = 'USA'
and avg(price) > 10
Does this mean you want the average prices across all products, or just the average price for those products in the USA? The syntax is no longer deterministic.
Here's another option:
SELECT *
FROM (
SELECT productname,unitprice,AVG(unitprice) OVER (PARTITION BY 1) avg_price
FROM products)
WHERE unitprice > avg_price
The reason your original SQL doesn't work is because you didn't tell Oracle how to compute the average. What table should it find it in? What rows should it include? What, if any, grouping do you wish to apply? None of that is communicated with "WHERE unitprice>(AVG(unitprice))".
Now, as a human, I can make a pretty educated guess that you intend the averaging to happen over the same set of rows you select from the main query, with the same granularity (no grouping). We can accomplish that either by using a sub-query to make a second pass on the table, as your second SQL did, or the newer windowing capabilities of aggregate functions to internally make a second pass on your query block results, as I did in my answer. Using the OVER clause, you can tell Oracle exactly what rows to include (ROWS BETWEEN ...) and how to group it (PARTITION BY...).
Related
I used COUNT (CUST_ID) as measure value to come up [Total No of Customer]. When I created new measure for [Average Profit per customer] by formula - [Total Profit] / [Total No of Customer], the error of Aggregate and non aggregate error prompted.
DB level:
Cust ID_____Profit
123_______100
234_______500
345_______350
567_______505
You must be looking for avg aggregate function.
Select cust_id, avg(profit)
From your_table
Group by cust_id;
Cheers!!
In your database table, you appear to have one data row per customer. Customer ID is serving as a unique primary key. The level of detail (or granularity) of the database table is the customer.
Given that, the simplest solution to your question is to display AVG([Profit]) -- without having [Cust ID] in the view (i.e. not on any shelf)
If the assumptions mentioned above are not correct, then you may need to employ other methods depending on how you define your question. I suggest making sure you understand what COUNT() actually does compared to COUNTD(). The behavior is not what people tend to assume. LOD calculations may prove useful. All described in the online help.
Put the calculations directly in the calculated field as:
SUM([Profit])/COUNT([CUST_ID])
This will give you aggregate and aggregate calculation.
If you want to show Average profit using a key like [CUST_ID], you can use LOD expression:
{FIXED [CUST_ID]: AVG[Profit]}
So i built a query for my leadership team that was correct, but i dont understand why oracle gave me the correct answer.
i have 3 tables that i needed to get data out of in order to get the total billed amount.
Here is my query (please forgive me, my 2nd post and im not sure how to properly format my querys)
select b.total_amount_billed as billed from t1.billing_information b
where b.billing_no in
(select h.billing_no
from t1.res_history h where h.res_seq_no in
(Select r.reservation_seq_no
from t1.res r where r.customer_order_no in ('THO40000') ))
so in the deepest select, i take the the sequence number where my customer order number was THO40000, this query returns 2 sequence numbers.
the second sub query returns the billing numbers for my order from the history table where the sequence number match, in this case for this order they both use the same billing number, 312000.
the final select, returns my total billed amount where it matched my billing numbers it found, in my case $110.
the query works, but what i dont understand is why is it not duplicated? why does it not return 110, for each time it found 312000, giving me 2 records of 110? the billing number is a PK in the billing_information table. im not sure why it worked without me using the distinct keyword on the query for the billing number.
anyway thanks for the help, ill do my best to explain if you have questions!
You are being saved because you used IN to get the billing_no values to use, rather than an INNER JOIN between the two tables using b.billing_no = h.billing_no. A join would have duplicated the records, but your IN query is essentially this:
select b.total_amount_billed as billed
from t1.billing_information b
where b.billing_no in (312000, 312000);
If there is a single row in billing_information having billing_no equal to 312000, it is in the list, so the WHERE condition is true and it is included in the results. The fact that it is in the list twice doesn't make the IN condition "more true".
I have a complex SphinxQL query which, at the end, orders results by a specific field, Preferred, so that all records with that indexed value of Preferred=1 come before all records w Preferred=0. I also order by weight() so basically I end up with:
Select * from idx_X where MATCH('various parameters') ORDER by Preferred DESC,Weight() Desc
The problem is that, though Preferred records come first I end up with records sorted by ID which puts results from one field, Vendor, in blocks so for instance I get:
Beta Shipping
Beta Shipping
Beta Shipping
Acme Widgets
Acme Widgets
Acme Widgets
Acme Widgets
Acme Widgets
Which doesn't serve my purposes in this case well (often one 'Vendor' will have 1000 results)
So I'm looking to essentially do:
ORDER BY Preferred DESC,weight() DESC,ID RANDOM
So that after getting to Preferred Vendors whose weight is (e.g.) 100, I will get random Vendors vs blocks of them.
Update: Though I did find what appears to be a possible answer in another Stackoveflow Question
The issue is it seems to require the SPH_SORT_EXTENDED and I am forced to use SPH_RANK_PROXIMITY (ranker=proximity) and I am unclear if I can combine ranking and sorting.
Update 2: If I remove my existing two-level Order and just do Order by Rand() it indeed returns random IDs. However I cannot add Rand() after Order by Preferred DESC,Weight() DESC or I get the following error:
1064 - sphinxql: syntax error, unexpected '(', expecting $end near '()
Sadly yes, RAND() only works as a single sort order expression, but it DOES work as a select function....
Select *, RAND() AS r from idx_X where MATCH('various parameters')
ORDER by Preferred DESC,Weight() Desc, r DESC
Or if want a more consistent ordering, but still mixed, can for example use CRC32() function on a string atribute
Select *, CRC32(title) AS r from idx_X where MATCH('various parameters')
ORDER by Preferred DESC,Weight() Desc, r DESC
Can also just limit results to a few per vendor (vendor will need to be an attribute)
Select * from idx_X where MATCH('various parameters')
GROUP 3 BY vendor_id ORDER by Preferred DESC,Weight() Desc
Group by N is a little known by very useful sphinx feature.
lag/lead analytic functions allow access to previous/next rows without join technique according official docs:
http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions070.htm
http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions074.htm
Does that mean that if I include fields which are not lag/lead - Oracle do join on this fields?
So if I query currency rates (to find holes - the day where are no rate defined):
select CURRENCY, RATE, XDATE, lead(XDATE) over (order by XDATE) from CURRENCY_RATE
I get lead(XDATE) for same CURRENCY as XDATE?
Or partition by keyword in lead expression must be used on CURRENCY to achieve this goal?
Your query make a lead without currency consideration.
If you want to sort by date for any currency, you need to add the partition by keyword :
select CURRENCY,
RATE,
XDATE,
lead(XDATE) over(partition by CURRENCY order by XDATE)
from CURRENCY_RATE
;
I found good explanation of analytical functions semantic in http://www.orafaq.com/node/55 :
Some functions support the window_clause inside the partition to further limit the records they act on. In the absence of any window_clause analytic functions are computed on all the records of the partition clause.
The functions SUM, COUNT, AVG, MIN, MAX are the common analytic functions the result of which does not depend on the order of the records.
Functions like LEAD, LAG, RANK, DENSE_RANK, ROW_NUMBER, FIRST, FIRST VALUE, LAST, LAST VALUE depends on order of records.
Another nice docs: http://www.oracle-base.com/articles/misc/analytic-functions.php
I have a table with a CreatedDate column. I want to order by the rows that have been in the database the longest, but need to determine the number of days by subtracting it from DateTime.Now.
I realise this is doable simply by ordering by the CreatedDate, but I need to do more than that.
I need to order the items by the amount of times they have been used within a period of time, in effect getting the most popular items.
So what I want to do is first determine the number of days, and after that divide this by the number of times each item has been used.
Step 1)
orderby (DateTime.Now.Subtract(t.CreatedDate.Value).Days)
Step 2)
orderby (t.UsedCount/DateTime.Now.Subtract(t.CreatedDate.Value).Days)
This results in the following error:
Method 'System.TimeSpan Subtract(System.DateTime)' has no supported translation to SQL.
Oddly, "Subtract()" doesn't work, but Minus does.
try:
orderby (t.UsedCount/(DateTime.Now - t.CreatedDate.Value).Days)
(Tested in LINQPad using the "master" database)
from sp in Spt_monitors
orderby sp.Io_busy / (DateTime.Now - sp.Lastrun).Days
select sp