I have a table that lists lots of item transactions. I need to get the last record for each item (the one dated the latest).
For example my table looks like this:
Item Date TrxLocation
XXXXX 1/1/13 WAREHOUSE
XXXXX 1/2/13 WAREHOUSE
XXXXX 1/3/13 WAREHOUSE
aaaa 1/1/13 warehouse
aaaa 2/1/13 WAREHOUSE
I want the data to come back as follows:
XXXXX 1/3/13 WAREHOUSE
AAAA 2/1/13 WAREHOUSE
I tried doing something like this but it is bringing back the wrong date
select Distinct ITEMNMBR
TRXLOCTN,
DATERECD
from TEST
where DateRecd = (select max(DATERECD)
from TEST)
Any help is appreciated.
You're on the right track. You just need to change your subquery to a correlated subquery, which means that you give it some context to the outer query. If you just run your subquery (select max(DATERECD) from TEST) by itself, what do you get? You get a single date that is the latest date in the whole table, regardless of item. You need to tie the subquery to the outer query by linking on the ITEMNMBR column, like this:
SELECT ITEMNMBR, TRXLOCTN, DATERECD
FROM TEST t
WHERE DateRecd = (
SELECT MAX (DATERECD)
FROM TEST tMax
WHERE tMax.ITEMNMBR = t.ITEMNMBR)
No need for subquery. You are querying a single table and need to select MAX(date) and GROUP BY item and TrxLocation.
SELECT Item, max(DATERECD) AS max_dt_recd, TrxLocation
FROM test
GROUP BY Item, TrxLocation
/
Related
lets say I have a table called order with following data. I need to get the customer_name along with the no. of orders they have placed.
Table name: order
id | customer_name | item
1 | Siddhant | TV
2 | Siddhant | Mobile
3 | Sankalp | Football
Desired output:
customer_name | no_of_orders
Siddhant | 2
Sankalp | 1
I tried below 2 queries to get the result:
select customer_name, count(customer_name) as no_of_orders
from order
group by customer_name;
This gives me the correct result but takes around ~10.5 secs to run
select ord.customer_name, count(ord1.customer_name) as no_of_orders
from order ord
inner join order ord1 on ord1.customer_name = ord.customer_name
group by ord.customer_name;
This gives me the square(correct count) in the result but runs in ~2 secs. I can get the square root to get the actual count.
I understand why the second query gives the square of the actual count in the output but can someone explain why it runs so fast compared to the first query?
PS: I am running these in Oracle SQL Developer.
The first version is the one you should be using here:
SELECT customer_name, COUNT(customer_name) AS no_of_orders
FROM "order"
GROUP BY customer_name;
Absent a WHERE or HAVING clause, adding an index might not be too helpful here, because Oracle has to basically touch every record in the table in order to do the aggregation. As to why the second version appears to be faster, I speculate that the benchmarks you are using are not representative, because they are based on a fairly small table size. If you scale your table data to be in the tens of thousands of rows, I predict that the first version will be substantially faster.
I have a set of related rows which I need to display in a single line. For example, the data I have is in different rows.
"ID" RecordDate "ExpType" "OrigBudget" "ActualCost"
1001 1-5-2017 Hardware $ 5000
1001 2-6-2017 Hardware $ 5200
The Original budget is approved at an earlier time for the same record but the Actual cost often differs and is recorded at a later date. I want the output as
ProjectID YearofEntry ExpenseType OrgBudget ActualCost <BR>
1001 2017 Hardware $ 5000 $ 5200 <BR>
I have tried group query to aggregate it based on ExpenseType and ProjectId but not successful in getting it into a single row so far.
if you always just have two rows for each ExpType - one with the original budget and one with the actual costs - you could simply use a GROUP BY:
SELECT ID AS ProjectID
,YEAR(RecordDate) AS YearofEntry
,ExpType AS ExpenseType
,MAX(OrigBudget) AS OrgBudget
,MAX(ActualCost) AS ActualCost
FROM yourtable
GROUP BY ID
,YEAR(RecordDate)
,ExpType
Try This:
SELECT ID,
Year([RecordDate]) AS YEARofEntry,
ExpType,
Sum(OrigBudget) AS SumOfOrigBudget,
Sum(ActualCost) AS SumOfActualCost
FROM youtable
GROUP BY ID,
Year([RecordDate]),
ExpType;
In a DB2 Database, I want to do the following simple mathematics using a SQL query:
AvailableStock = SupplyStock - DemandStock
SupplyStock is stored in 1 table in 1 row, let's call this table the Supply table.
So the Supply table has this data:
ProductID | SupplyStock
---------------------
109 10
244 7 edit: exclude this product from the search
DemandStock is stored in a separate table Demand, where demand is logged as each customer logs demand during a customer order journey. Example data from the Demand table:
ProductID | DemandStock
------------------------
109 1
244 4 edit: exclude this product
109 6
109 2
So in our heads, if I want to calculate the AvailableStock for product '109', Supply is 10, Demand for product 109 totals to 9, and so Available stock is 1.
How do I do this in one select query in DB2 SQL?
The knowledge I have so far of some of the imagined steps in PseudoCode:
I select SupplyStock where product ID = '109'
I select sum(DemandStock) where product ID = '109'
I subtract SupplyStock from DemandStock
I present this as a resulting AvailableStock
The results will look like this:
Product ID | AvailableStock
109 9
I'd love to get this selected in one SQL select query.
Edit: I've since received an answer (that was almost perfect) and realised the question missed out some information.
This information:
We need to exclude data from products we don't want to select data for, and we also need to specifically select product 109.
My apologies, this was omitted from the original question.
I've since added a 'where' to select the product and this works for me. But for future sake, perhaps the answer should include this information too.
You do this using a join to bring the tables together and group by to aggregate the results of the join:
select s.ProductId, s.SupplyStock, sum(d.DemandStock),
(s.SupplyStock - sum(d.DemandStock)) as Available
from Supply s left join
Demand d
on s.ProductId = d.ProductId
where s.ProductId = 109
group by s.ProductId, s.SupplyStock;
I hit this issue regularly but here is an example....
I have a Order and Delivery Tables. Each order can have one to many Deliveries.
I need to report totals based on the Order Table but also show deliveries line by line.
I can write the SQL and associated Access Report for this with ease ....
SELECT xxx
FROM
Order
LEFT OUTER JOIN
Delivery on Delivery.OrderNO = Order.OrderNo
until I get to the summing element. I obviously only want to sum each Order once, not the 1-many times there are deliveries for that order.
e.g. The SQL might return the following based on 2 Orders (ignore the banalness of the report, this is very much simplified)
Region OrderNo Value Delivery Date
North 1 £100 12-04-2012
North 1 £100 14-04-2012
North 2 £73 01-05-2012
North 2 £73 03-05-2012
North 2 £73 07-05-2012
South 3 £50 23-04-2012
I would want to report:
Total Sales North - £173
Delivery 12-04-2012
Delivery 14-04-2012
Delivery 01-05-2012
Delivery 03-05-2012
Delivery 07-05-2012
Total Sales South - £50
Delivery 23-04-2012
The bit I'm referring to is the calculation of the £173 and £50 which the first of which obviously shouldn't be £419!
In the past I've used things like MAX (for a given Order) but that seems like a fudge.
Surely there must be a regular answer to this seemingly common problem but I can't find one.
I don't necessarily need the code - just a helpful point in the right direction.
Many thanks,
Chris.
A roll up operator may not look pretty. However, it would do the regular aggregates that you see now, and it show the subtotals of the order. This is what you're looking for.
SELECT xxx
FROM
Order
LEFT OUTER JOIN
Delivery on Delivery.OrderNO = Order.OrderNo
GROUP BY xxx
WITH ROLLUP;
I'm not exactly sure how the rest of your query is set up, but it would look something like this:
Region OrderNo Value Delivery Date
North 1 £100 12-04-2012
North 1 £100 14-04-2012
North 2 £73 01-05-2012
North 2 £73 03-05-2012
North 2 £73 07-05-2012
NULL NULL f419 NULL
I believe what you want is called a windowing function for your aggregate operation. It looks like the following:
SELECT xxx, SUM(Value) OVER (PARTITION BY Order.Region) as OrderTotal
FROM
Order
LEFT OUTER JOIN
Delivery on Delivery.OrderNO = Order.OrderNo
Here's the MSDN article. The PARTITION BY tells the SUM to be done separately for each distinct Order.Region.
Edit: I just noticed that I missed what you said about orders being counted multiple times. One thing you could do is SUM() the values before joining, as a CTE (guessing at your schema a bit):
WITH RegionOrders AS (
SELECT Region, OrderNo, SUM(Value) OVER (PARTITION BY Region) AS RegionTotal
FROM Order
)
SELECT Region, OrderNo, Value, DeliveryDate, RegionTotal
FROM RegionOrders RO
INNER JOIN Delivery D on D.OrderNo = RO.OrderNo
I have the following "COMPANIES_BY_NEWS_REPUTATION" in my JavaDB database (this is some random data just to represent the structure)
COMPANY | NEWS_HASH | REPUTATION | DATE
-------------------------------------------------------------------
Company A | 14676757 | 0.12345 | 2011-05-19 15:43:28.0
Company B | 454564556 | 0.78956 | 2011-05-24 18:44:28.0
Company C | 454564556 | 0.78956 | 2011-05-24 18:44:28.0
Company A | -7874564 | 0.12345 | 2011-05-19 15:43:28.0
One news_hash may relate to several companies while a company can relate to several news_hashes as well. Reputation and date are bound to the news_hash.
What I need to do is calculate the average reputation of last 5 news for every company. In order to do that I somehow feel that I need to user 'order by' and 'offset' in a subquery as shown in the code below.
select COMPANY, avg(REPUTATION) from
(select * from COMPANY_BY_NEWS_REPUTATION order by "DATE" desc
offset 0 rows fetch next 5 row only) as TR group by COMPANY;
However, JavaDB allows neither ORDER BY, nor OFFSET in a subquery. Could anyone suggest a working solution for my problem please?
Which version of JavaDB are you using? According to the chapter TableSubquery in the JavaDB documentation, table subqueries do support order by and fetch next, at least in version 10.6.2.1.
Given that subqueries can be ordered and the size of the result set can be limited, the following (untested) query might do what you want:
select COMPANY, (select avg(REPUTATION)
from (select REPUTATION
from COMPANY_BY_NEWS_REPUTATION
where COMPANY = TR.COMPANY
order by DATE desc
fetch first 5 rows only))
from (select distinct COMPANY
from COMPANY_BY_NEWS_REPUTATION) as TR
This query retrieves all distinct company names from COMPANY_BY_NEWS_REPUTATION, then retrieves the average of the last five reputation rows for each company. I have no idea whether it will perform sufficiently, that will likely depend on the size of your data set and what indexes you have in place.
If you have a list of unique company names in another table, you can use that instead of the select distinct ... subquery to retrieve the companies for which to calculate averages.