I have a table called AssetTable which stores AssetId
I have another table called AssetBookTable which stores two fields BookId and CurrentOperationsTax
Another table AssetBook that stores AssetId and BookId as foriegn keys.
Now, I have a situation in which I have to filter records based on
AssetBookTable.CurrentOperationsTax
This, is what I am getting now,
And this, is what I want:
**
The logic is that I want only one BookId per AssetId that has either Current/Operation/Tax for CurrentOperationsTax field.
**
Here's the SQL fiddle written so far:
SQLFiddle
Any help is greatly appreciated.
You can simple remove the GROUP BY BookID. But of course you then need to aggregate the BookID some how. Here using the MIN() function:
SELECT
ab.AssetId
,MIN(ab.BookId) as BookID
,abt.CuurentOperationsTax
FROM
AssetBook ab
JOIN AssetTable at ON at.AssetId = ab.AssetId
JOIN AssetBookTable abt ON abt.BookId = ab.BookId
GROUP BY
ab.AssetId
,abt.CuurentOperationsTax
http://sqlfiddle.com/#!6/e3477/42
I prefer using the ROW_NUMBER approach. It does require the use of a subquery. In summary it is grouping the records by the CuurentOperationsTax number and ordering by book id and giving the row number for each grouping. Then in the outer select I filter out how many I want for each grouping. In this example just 1.
SELECT AssetId
,BookId
,CuurentOperationsTax
,RowNum
FROM (
SELECT
ab.AssetId
,ab.BookId
,abt.CuurentOperationsTax
,ROW_NUMBER() OVER(PARTITION BY abt.CuurentOperationsTax ORDER BY ab.BookId) AS RowNum
FROM
AssetBook ab
JOIN AssetTable AT ON AT.AssetId = ab.AssetId
JOIN AssetBookTable abt ON abt.BookId = ab.BookId
) AS b
WHERE b.RowNum = 1
Related
i am a total beginner in SQL. So i have two tables ( table a and table b )
table a holds people with unique IDs, table b holds multiple rows for each person of table a and also the persons ID ( for a possible join ) . the rows in table b are sorted by the columnn row_number.
How can i select all people but only the row of table b with the highest row_number ?
i hope you could somewhat understand me.
Cheers
If i got you right:
SELECT a.persons_ID
,b.rn
FROM A
INNER JOIN
(
SELECT MAX(row_number_column) AS rn
,persons_ID
FROM B
GROUP BY persons_ID
) sub
ON sub.persons_ID = A.persons_ID
The subselect in the inner joins groups your data of table B. So there will be just one row for each persons_ID - the row with the highest row_number_column.
Finally just a simple join on persons_ID.
If you don't need any other information than the person ID and the last row_number per person, then it is quite trivial. Let's call the first table person and the second visit:
select person_id,
max(row_number) max_row_number
from visit
group by person_id
If you need some other information from the first table, like person.name, then perform the join:
select person.person_id,
person.name,
max(visit.row_number) max_row_number
from person
inner join visit on visit.person_id = person.person_id
group by person.person_id,
person.name
If you need some other information from the second table, like visit.present, then modern databases support the row_number() window function (not to be confused with the column that you have):
select name,
base.row_number,
present
from (
select person.name,
row_number() over (partition by visit.person_id
order by visit.row_number desc) rn,
visit.row_number,
visit.present
from person
inner join visit on visit.person_id = person.person_id
) base
where rn = 1
NB: I would strongly advise to rename the column row_number to some other name, as row_number is an analytic function in many databases.
I've been banging my head against the wall for something that I think should be simple but just cant get to work.
I'm trying to retrieve the row with the highest multi_flag value when I join table A and table B but I can't seem to get the SQL right because it returns all the rows rather than the one with the highest multi_flag value.
Here are my tables...
Table A
Table B
This is almost my desired result but only if I leave out the value_id row
SELECT CATALOG, VENDOR_CODE, INVLINK, NAME_ID, MAX(multi_flag) AS multiflag
FROM TBLINVENT_ATTRIBUTE AS A
INNER JOIN TBLATTRIBUTE_VALUE AS B
ON A.VALUE_ID = B.VALUE_ID
GROUP BY CATALOG, VENDOR_CODE, INVLINK, NAME_ID
ORDER BY CATALOG DESC
This is close to what I want to retreive but not quite notice how it returns unique name_id and the highest multi_flag but I also need the value_id that belongs to such multi_flag / name_id grouping...
If I include the value_id in my SQL statement then it returns all rows and is no longer grouped
Notic ein the results below how it no longer returns the row for the highest multi_flag and how all the different values for name_id (Ex. name_id 1) are also returned
You can choose to use a sub-query, derived table or CTE to solve this problem. Performance will be depending on the amount of data you are querying. To achieve your goal of getting the max multiflag you must first get the max value based on the grouping you want to achieve this you can use a CTE or sub query. The below CTE will give the max multi_flag by value that you can use to get the max multi_flag and then you can use that to join back to your other tables. I have three joins in this example but this can be reduce and as far a performance it may be better to use a subquery but you want know until you get the se the actual execution plans side by side.
;with highest_multi_flag as
(
select value_id, max(multi_flag) AS multiflag
FROM TBLINVENT_ATTRIBUTE
group by value_id
)
select A.CATALOG, a.VENDOR_CODE, a.INVLINK, b.NAME_ID,m.multiflag
from highest_multi_flag m
inner join TBLINVENT_ATTRIBUTE AS A on a.VALUE_ID =b. m.VALUE_ID
INNER JOIN TBLATTRIBUTE_VALUE AS B ON m.VALUE_ID = B.VALUE
You can use Lateral too, its an other solution
SELECT
A.CATALOG, A.VENDOR_CODE, A.INVLINK, B.NAME_ID, M.maxmultiflag
FROM TBLINVENT_ATTRIBUTE AS A
inner join lateral
(
select max(B.multi_flag) as maxmultiflag from TBLINVENT_ATTRIBUTE C
where A.VALUE_ID = C.VALUE_ID
) M on 1=1
INNER JOIN TBLATTRIBUTE_VALUE AS B ON M.maxmultiflag = B.VALUE
I have a table like this:
I need group this table latest date for every ID.
I mean, I want to get last row every ID. Here is my query:
SELECT DISTINCT ch.Date,ID FROM dbo.tblrisk AS rk
inner join (Select TableIdentity, [Date] from tblCommonHistory ) ch
ON ch.TableIDentity = rk.ID order by ID
How can I do what I want?
EDIT: This query worked for me:
SELECT DISTINCT ch.dt,ID FROM dbo.tblrisk AS rk
inner join (Select TableIdentity, max([Date]) as dt from tblCommonHistory group by TableIdentity) ch ON ch.TableIDentity = rk.ID order by ID
Just use aggregation:
select TableIdentity, max([date])
from tblCommonHistory
group by TableIdentity;
Your question only mentions one table. Your query has two; I don't understand the discrepancy.
It's strange that you have duplicated TableIdentity in tblCommonHistory, but otherwise you should not be getting multiple dates for the same ID from your query.
And also, the only reason to join the 2 tables seems to be that you need to skip those ID that are not present in the tblrisk (is it what you need to do?)
In that case, I'd suggest
SELECT max(ch.Date) AS [Date],ID FROM dbo.tblrisk AS rk
inner join tblCommonHistory AS ch ON ch.TableIDentity = rk.ID
group by ID order by ID
I'm working on a database meant for auctions and I would like get the id of all the winning bids. The hard part is extracting it from a subquery that returns 2 columns: the id and the amount.
It looks something like this:
SELECT id FROM Bid WHERE id IN (Select ID,max(amount) FROM Bid group by bid.idAuction)
Can I somehow extract just one column from the subquery? Any other sugestions to do this task are helpfull too.
Thank you!
Your query is close, but you need a correlated subquery to make this work:
SELECT b.id
FROM Bid b
WHERE b.amount = (SELECT max(amount)
FROM Bid b2
WHERE b2.idAuction = b.idAuction
);
SELECT id, maxBid.MAmount, Bid.Amount
FROM Bid
INNER JOIN (Select ID,max(amount) mamount FROM Bid group by bid.idAuction) MaxBid
on MaxBid.ID = Bid.ID
RDBMS and SQL operate most effectively in SET based operations. So in this case we generate a set based on ID and max bid. We then join it back to the base set so that only the max bids are treturned.
I have a customers and orders table in SQL Server 2008 R2. Both have indexes on the customer id (called id). I need to return details about all customers in the customers table and information from the orders table, such as details of the first order.
I currently left join my customers table on a subquery of the orders table, with the subquery returning the information I need about the orders. For example:
SELECT c.id
,c.country
,First_orders.product
,First_orders.order_id
FROM customers c
LEFT JOIN SELECT( id,
product
FROM (SELECT id
,product
,order_id
,ROW_NUMBER() OVER (PARTITION BY id ORDER BY Order_Date asc) as order_No
FROM orders) orders
WHERE Order_no = 1) First_Orders
ON c.id = First_orders.id
I'm quite new to SQL and want to understand if I'm doing this efficiently. I end up left joining quite a few subqueries like this onto the customers table in one select query and it can take tens of minutes to run.
So am I doing this efficiently or can it be improved? For example, I'm not sure if my index on id in the orders table is of any use and maybe I could speed up the query by creating a temporary table of what is in the subquery first and creating a unique index on id in the temporary table so SQL Server knows id is now a unique column and then joining my customers table to this temporary table? I typically have one or two million rows in the customers and orders tables.
Many thanks in advance!
You can remove one of your subqueries to make it a little more efficient:
SELECT c.id
,c.country
,First_orders.product
,First_orders.order_id
FROM customers c
LEFT JOIN (SELECT id
,product
,order_id
,ROW_NUMBER() OVER (PARTITION BY id ORDER BY Order_Date asc) as order_No
FROM orders) First_Orders
ON c.id = First_orders.id AND First_Orders.order_No = 1
In your above query, you need to be careful where you place your parentheses as I don't think it will work. Also, you're returning product in your results, but not including in your nested subquery.
For someone who is just learning SQL, your query looks pretty good.
The index on customers may or may not be used for the query -- you would need to look at the execution plan. An index on orders(id, order_date) could be used quite effectively for the row_number function.
One comment is on the naming of fields. The field orders.id should not be the customer id. That should be something like 'orders.Customer_Id`. Keeping the naming system consistent across tables will help you in the future.
Try this...its easy to understand
;WITH cte
AS (
SELECT id
,product
,order_id
,ROW_NUMBER() OVER (
PARTITION BY id ORDER BY Order_Date ASC
) AS order_No
FROM orders
)
SELECT c.id
,c.country
,c1.Product
,c1.order_id
FROM customers c
INNER JOIN cte c1 ON c.id = c1.id
WHERE c1.order_No = 1