I have a table 'Cashup_Till' that records all data on what a particular till has recorded in a venue for a given day, each venue has multiple tills all with a designated number 'Till_No'. I need to get the previous 2 days entries for each till number. For each till Individually I can do this...
SELECT TOP 2 T.* FROM CashUp_Till T
WHERE T.Till_No = (Enter Till Number Here)
ORDER BY T.Till_Id DESC
Some venues have 20-30 tills so Ideally I need to do all the tills in one call. I can pass in a user defined table type of till numbers, then select them in a subquery, but that's as far as my SQL knowledge takes me, does anyone have a solution?
Here is one way:
SELECT T.*
FROM (SELECT T.*,
ROW_NUMBER() OVER (PARTITION BY Till_No ORDER BY Till_Id DESC) as seqnum
FROM CashUp_Till T
) T
WHERE seqnum <= 2;
This assumes that there is one record per day, which I believe is suggested by the question.
If you have a separate table of tills, then:
select ct.*
from t cross apply
(select top 2 ct.*
from cashup_till ct
where ct.till_no = t.till_no
order by till_id desc
) ct;
Related
for example i have data like this(sql server)
id name
4 anu
3 lohi
1 pras
2 chand
i want 2nd record in a table (means 3 lohi)
if i use row_number() function its changes the order and i get (2 chand)
i want 2nd record from table data
can anyonr please give me the query fro above scenario
There is no such thing as the nth row in a table. And for a simple reason: SQL tables represent unordered sets (technically multi-sets because they allow duplicates).
You can do what you want use offset/fetch:
select t.*
from t
order by id desc
offset 1 fetch first 1 row only;
This assumes that the descending ordering on id is what you want, based on your example data.
You can also do this using row_number():
select t.*
from (select t.*,
row_number() over (order by id desc) as seqnum
from t
) t
where seqnum = 2;
I should note that that SQL Server allows you to assign row_number() without having an effective sort using something like this:
select t.*
from (select t.*,
row_number() over (order by (select NULL)) as seqnum
from t
) t
where seqnum = 2;
However, this returns an arbitrary row. There is no guarantee it returns the same row each time it runs, nor that the row is "second" in any meaningful use of the term.
In SQL Server, I am attempting to pull the second latest NOTE_ENTRY_DT_TIME (items highlighted in screenshot). With the query written below it still pulls the latest date (I believe it's because of the grouping but the grouping is required to join later). What is the best method to achieve this?
SELECT
hop.ACCOUNT_ID,
MAX(hop.NOTE_ENTRY_DT_TIME) AS latest_noteid
FROM
NOTES hop
WHERE
hop.GEN_YN IS NULL
AND hop.NOTE_ENTRY_DT_TIME < (SELECT MAX(hope.NOTE_ENTRY_DT_TIME)
FROM NOTES hope
WHERE hop.GEN_YN IS NULL)
GROUP BY
hop.ACCOUNT_ID
Data sample in the table:
One of the "easier" ways to get the Nth row in a group is to use a CTE and ROW_NUMBER:
WITH CTE AS(
SELECT Account_ID,
Note_Entry_Dt_Time,
ROW_NUMBER() OVER (PARTITION BY AccountID ORDER BY Note_Entry_Dt_Time DESC) AS RN
FROM dbo.YourTable)
SELECT Account_ID,
Note_Entry_Dt_Time
FROM CTE
WHERE RN = 2;
Of course, if an ACCOUNT_ID only has 1 row, then it will not be returned in the result set.
The OP's statement "The row will not always be 2." from the comments conflicts with their statement "I am attempting to pull the second latest NOTE_ENTRY_DT_TIME" in the question. At a best guess, this means that the OP has rows with the same date, that could be the "latest" date. If so, then would simply need to replace ROW_NUMBER with DENSE_RANK. Their sampple data, however, doesn't suggest this is the case.
You can use window functions:
select *
from (
select
n.*,
row_number() over(partition by account_id order by note_entry_dt_time desc) rn
from notes n
) t
where rn = 2
I have a large data set with about 100 million rows that I want to 'compress' the data set and get a 1% sample of the entire dataset while ensuring relativity.
How can such query be implemented?
Step 1: create the helper table
You can use aggregation to group records by visit_id, and CROSS JOIN with a query that computes the total number of records in the table to compute the distribution percent:
CREATE TABLE my_helper AS
SELECT
t.visit_number,
COUNT(*) visit_count,
SUM(t.purchase_id) sum_purchase,
COUNT(*)/total.cnt distribution
FROM
mytable t
CROSS JOIN (SELECT COUNT(*) cnt FROM mytable) total
GROUP BY t.visit_number
Step 2: sample the main table using the helper table
Within a subquery, you can use ROW_NUMBER() OVER(PARTITION BY visit_number ORDER BY RANDOM()) to assign a random rank to each record within groups of records sharing the same visit_id. Then, in the outer query, you can join on the helper table to select the corect amount of records for each visit_id:
SELECT x.*
FROM (
SELECT
t.*,
ROW_NUMBER() OVER(PARTITION BY visit_number ORDER BY RANDOM()) rn
FROM mytable t
) x
INNER JOIN my_helper h ON h.visit_number = x.visit_number
WHERE x.rn <= 1000000 * h.distribution
Side notes:
this only works if there are indeed more than 1 million record in the source table
the exact number of records in the output might be slightly below or above 1 million (depending on the distribution in the original table)
it should be possible to combine both queries into a single one, which would avoid the need to use a helper table
This is doable. A quick way is to take every nth record only.
1) order by a random column (probably ID)
2) apply a nownum() attribute
3) apply a mod(rownum) = 0 on whatever percent makes sense (e.g. 1% would be rownum mod 100)
You may need steps 1/2 in a sub query and step 3 on the outside.
Enjoy and good luck!
I am trying to find whether a person (id = A3) is continuously active in a program at least five months or more in a given year (2013). Any suggestion would be appreciated. My data look like as follows:
You simply use group by and a conditional expression:
select id,
(case when count(ActiveMonthYear) >= 5 then 'YES!' else 'NAW' end)
from table t
where ListOfTheMonths between '201301' and '201312'
group by id;
EDIT:
I suppose "continuously" doesn't just mean any five months. For that, there are various ways. I like the difference of row numbers approach
select distinct id
from (select t.*,
(row_number() over (partition by id order by ListOfTheMonths) -
count(ActiveMonthYear) over (partition by id order by ListOfTheMonths)
) as grp
from table t
where ListOfTheMonths between '201301' and '201312'
) t
where ActiveMonthYear is not null
group by id, grp
having count(*) >= 5;
The difference in the subquery is constant for groups of consecutive active months. This is then used a grouping. The result is a list of all ids that meet this criteria. You can add a where for a particular id (do it in the subquery).
By the way, this is written using select distinct and group by. This is one of the rare cases where these two are appropriately used together. A single id could have two periods of five months in the same year. There is no reason to include that person twice in the result set.
i'm currently developing a news-site.
So here is the problem. I want to select the 2nd and 3rd row in a TOP 3.
SELECT TOP 3 * FROM News ORDER BY Date DESC;
I want to remove the 1st row and only return the 2nd and 3rd row.
Can anyone help?
Try this:
SELECT TOP 2 FROM
( SELECT TOP 3 * FROM News ORDER BY Date DESC ) xx
ORDER BY Date
SQLFiddle: http://www.sqlfiddle.com/#!3/dbb7e/5
You can also do this generically using window functions:
select n.*
from (SELECT n.*, row_number() over (order by date desc) as seqnum
FROM News n
) n
where n.seqnum >= 2 and n.seqnum <= 3;
I just offer this as a general solution. You can also ensure that you get everything from the second date (in case there are more than two items on that date) by using dense_rank() rather than row_number().
If you know that no two dates will be the same, you could add
where date not in (select max(date) from News)
Or you could look at rowid if you know that the first item will have rowid=0, for example if you created a temp table with the results of your initial query.
I assume, you somehow know what you Top 3 news are by ordering by date descending.
Therfore you should use the LIMIT clause with an OFFSET [For sqlite]
SELECT * FROM News ORDER BY Date DESC LIMIT 2 OFFSET 1;
Select top 2 * from News cross apply (select top 3 from news order by date desc)x