I have a nested table in a object database. Now I want that row, that has the most rows in the nested table.
The problem is, I don't have a object database, but I have to learn some SQL statements for a exam. For now my query looks like this:
SELECT o.Order_Number
FROM Order o, TABLE(o.Position) pos
GROUP BY o.Order_Number
HAVING COUNT (*) >= all
(SELECT COUNT(*)
FROM pos);
With ANSI SQL for most DBs you can use a little trickery with the RANK() function
SELECT Order_Number, Order_Count
FROM (
SELECT Order_Number, COUNT(1) Order_Count,
RANK() OVER (ORDER BY COUNT(1) DESC) Ranking
FROM [Position]
GROUP BY Order_Number
) a
WHERE Ranking = 1
Related
Looking for a better solution, this query I wrote works for me, I would like to know if there is any better approach or same logic which I could used in the case expression.
I have written a query which give the max count for each id for respective quarter using window function and then pulling seqnum which is 1 and giving the results.
I would like to know is it possible to use the same query in case expression with similar logic.
select id,Quarter_yr, country
from (select id,Quarter_yr, country, count(*) as cnt,
row_number() over (partition by id, Quarter_yr order by count(*) desc) as seqnum
from table
group by id,Quarter_yr,country
) t
where seqnum = 1;
Maybe this query is what you're looking for
select top(1) id, Quarter_yr, country, count(*) as cnt
from table
group by id, Quarter_yr, country
order by count(*) desc;
I am using MySQL database. So, there are two columns I am working on, CustomerId, and OrderDate. I want to find a second-order date (2nd minimum order date) for each customer.
If you are using MySQL 8+, then ROW_NUMBER can be used here:
WITH cte AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY CustomerId ORDER BY OrderDate) rn
FROM yourTable
)
SELECT CustomerId, OrderDate
FROM cte
WHERE rn = 2;
I would recommend using dense_rank as it can give you correct result even if there is duplicate order_date as follows:
SELECT * FROM
(SELECT t.*, DENSE_RANK() OVER (PARTITION BY CustomerId ORDER BY OrderDate) dr
FROM yourTable t
) t where dr = 2;
You can use corelated sub-query as follows if your MySQL version do not support analytical functions as follows:
SELECT T.*
FROM YOURTABLE T
WHERE 1 = (
SELECT COUNT(DISTINCT ORDER_DATE)
FROM YOURTABLE TT
WHERE TT.ORDER_DATE > T.ORDER_DATE
)
I would use a subquery like this:
select o.*
from orders o
where o.order_date = (select o2.order_date
from orders o2
where o2.customer_id = o.customer_id
order by o2.order_date
limit 1 offset 1
);
The subquery is a correlated subquery that returns the second date. If you want the second date with other columns, it can be moved to the select.
With an index on (customer_id, order_date), this is likely to be the fastest solution.
This assumes that there is one row per date (or that if there are multiple rows, "second" can be the earliest date). If you want the second distinct date then use select distinct int he subquery -- however select distinct and group by would incur additional overhead.
I have a table with multiple rows of the same member id. I need only distinct rows based on 2 unique columns
Ex: there are 100 different customers, the table has 1000 rows because every customer has multiple cities and segments assigned to him.
I need 100 distinct rows for these customers depending on a unique segment and city combination. There is no specific requirement for this combination, just the first from the table is fine.
So, currently the table is somewhat like this,
Hope this helps.
use row_number()
select * from (select *,row_number() over(partition by memberid order by sales) rn
from table_name
) a where a.rn=1
Handy sql-server top(1) with ties syntax for that
select top(1) with ties t.*
from table_name t
order by row_number() over(partition by memberid order by sales)
As you have no paticular requirement for which exactly row to select, any column will do at order by, it can be null as well
select top(1) with ties t.*
from table_name t
order by row_number() over(partition by memberid order by (select null))
The simplest way to do this is to use the ROW_NUMBER() OVER(GROUP BY...) syntax. You have no need to use an order by, since you want an arbitrary row, but only one, for each member.
Since you need only the expected data, and not the Row_Number value, make sure that you detail the fields returned, like below:
SELECT
MemberId,
city,
segment,
sales
FROM (
SELECT *
ROW_NUMBER() OVER (GROUP BY MemberId) as Seq
FROM [Status]
) src
WHERE Seq = 1
how to add to the query max(o.Acct)-1 rows. I need to visualize the last two o.Acct rows. My query is currently showing only the max(o.Acct)
SELECT Max(o.Acct) AS [MaxAcct],o.ObjectID,o.Opertype
FROM Operations o
GROUP By o.ObjectID,o.Opertype
If you want to see the last two rows (per group), you're better off using ROW_NUMBER() rather than GROUP BY.
SELECT
*
FROM
(
SELECT
*,
ROW_NUMBER() OVER (PARTITION BY ObjectID,
Opertype
ORDER BY Acct DESC
)
AS sequence_id
FROM
Operations
)
sortedOperations
WHERE
sequence_id <= 2
ORDER BY
ObjectID,
Opertype,
Acct
If you want the last two of something, I'm thinking order by and top. Something like this:
select top (2) o.*
from Operations o
order by o.acct desc;
I'm using ROW_NUMBER() and a derived table to fetch data from the derived table result.
However, I get the error message telling me I don't have the appropriate columns in the GROUP BY clause.
Here's the error:
Column 'tblCompetition.objID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause
What column am I missing? Or am I doing something else wrong? Find below the query that is not working, and the (more simple) query that is working.
SQL Server 2008.
Query that isn't working:
SELECT
objID,
objTypeID,
userID,
datAdded,
count,
sno
FROM
(
SELECT scc.objID,scc.objTypeID,scc.userID,scc.datAdded,
COUNT(sci.favID) as count,
ROW_NUMBER() OVER(PARTITION BY scc.userID ORDER BY scc.unqID DESC) as sno
FROM tblCompetition scc
LEFT JOIN tblFavourites sci
ON sci.favID = scc.objID
AND sci.datTimeStamp BETWEEN #datStart AND #datEnd
) as t
WHERE sno <= 2 AND objTypeID = #objTypeID
AND datAdded BETWEEN #datStart AND #datEnd
GROUP BY objID,objTypeID,userID,datAdded,count,sno
Simple query that is working:
SELECT objId,objTypeID,userId,datAdded FROM
(
SELECT objId,objTypeID,userId,datAdded,
ROW_NUMBER() OVER(PARTITION BY userId ORDER BY unqid DESC) as sno
FROM tblRdbCompetition
) as t
WHERE sno<=2 AND objtypeid=#objTypeID
AND datAdded BETWEEN #datStart AND #datEnd
Thank you!
you need the GROUP BY in your subquery since that's where the aggregate is:
SELECT
objID,
objTypeID,
userID,
datAdded,
count,
sno
FROM
(
SELECT scc.objID,scc.objTypeID,scc.userID,scc.datAdded,
COUNT(sci.favID) as count,
ROW_NUMBER() OVER(PARTITION BY scc.userID ORDER BY scc.unqID DESC) as sno
FROM tblCompetition scc
LEFT JOIN tblFavourites sci
ON sci.favID = scc.objID
AND sci.datTimeStamp BETWEEN #datStart AND #datEnd
GROUP BY scc.objID,scc.objTypeID,scc.userID,scc.datAdded) as t
WHERE sno <= 2 AND objTypeID = #objTypeID
AND datAdded BETWEEN #datStart AND #datEnd
You cannot have count in a group by clause. Infact the count is derived when you have other fields in group by. Remove count from your Group by.
In the innermost query you are using
COUNT(sci.favID) as count,
which is an aggregate, and you select other non-aggregating columns along with it.
I believe you wanted an analytic COUNT instead:
SELECT objID,
objTypeID,
userID,
datAdded,
count,
sno
FROM (
SELECT scc.objID,scc.objTypeID,scc.userID,scc.datAdded,
COUNT(sci.favID) OVER (PARTITION BY scc.userID ) AS count,
ROW_NUMBER() OVER (PARTITION BY scc.userID ORDER BY scc.unqID DESC) as sno
FROM tblCompetition scc
LEFT JOIN
tblFavourites sci
ON sci.favID = scc.objID
AND sci.datTimeStamp BETWEEN #datStart AND #datEnd
) as t
WHERE sno = 1
AND objTypeID = #objTypeID