Case statements: SQL Server - sql

id date value
------------------
1 1 null
1 2 a
1 3 b
1 4 null
2 1 null
2 2 null
2 3 null
2 4 null
2 5 null
If value is null in all id's then max of date of that id and if we have value then max of date with value id.
Required output is:
id date value
-----------------
1 3 b
2 5 null

Typical method for this type of problem is row_number(). You can create a CASE expression to define a priority:
select id,
date,
value
from (
select id,
date,
value,
row_number() over (partition by id order by case when value is not null then 1 else 2 end asc, date desc) rn
from UnnamedTable
) t1
where t1.rn = 1

Sql Fiddle Demo
WITH cte as (
SELECT id,
[date],
[value],
ROW_NUMBER() OVER (PARTITION BY [ID] ORDER BY [value] DESC, [date] DESC) as rn
FROM Table1
)
SELECT *
FROM cte
WHERE rn = 1

Related

ROW_Number with Custom Group

I am trying to have row_number based on custom grouping but I am not able to produce it.
Below is my Query
CREATE TABLE mytbl (wid INT, id INT)
INSERT INTO mytbl Values(1,1),(2,1),(3,0),(4,2),(5,3)
Current Output
wid id
1 1
2 1
3 0
4 2
5 3
Query
SELECT *, RANK() OVER(PARTITION BY wid, CASE WHEN id = 0 THEN 0 ELSE 1 END ORDER BY ID)
FROM mytbl
I would like to rank the rows based on custom condition like if ID is 0 then I have start new group until I have non 0 ID.
Expected Output
wid id RN
1 1 1
2 1 1
3 0 1
4 2 2
5 3 2
Guessing here, as we don't have much clarification, but perhaps this:
SELECT wid,
id,
COUNT(CASE id WHEN 0 THEN 1 END) OVER (ORDER BY wid ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING) +1 AS [Rank]
FROM mytbl ;
If I understand you correctly, you may use the next approach. Note, that you need to have an ordering column (I assume this is wid column):
Statement:
;WITH ChangesCTE AS (
SELECT
*,
CASE WHEN LAG(id) OVER (ORDER BY wid) = 0 THEN 1 ELSE 0 END AS ChangeIndex
FROM mytbl
), GroupsCTE AS (
SELECT
*,
SUM(ChangeIndex) OVER (ORDER BY wid) AS GroupIndex
FROM ChangesCTE
)
SELECT
wid,
id,
DENSE_RANK() OVER (ORDER BY GroupIndex) AS Rank
FROM GroupsCTE
Result:
wid id Rank
1 1 1
2 1 1
3 0 1
4 2 2
5 3 2
without much clarification on the logic required, my understanding is you want to increase the Rank by 1 whenever id = 0
select wid, id,
[Rank] = sum(case when id = 0 then 1 else 0 end) over(order by wid)
+ case when id <> 0 then 1 else 0 end
from mytbl
Try this,
CREATE TABLE #mytbl (wid INT, id INT)
INSERT INTO #mytbl Values(1,1),(2,1),(3,0)
,(4,2),(5,3),(6,0),(7,4),(8,5),(9,6)
;with CTE as
(
select *,ROW_NUMBER()over(order by wid)rn
from #mytbl where id=0
)
,CTE1 as
(
select max(rn)+1 ExtraRN from CTE
)
select a.* ,isnull(ca.rn,ca1.ExtraRN) from #mytbl a
outer apply(select top 1 * from CTE b
where a.wid<=b.wid )ca
cross apply(select ExtraRN from CTE1)ca1
drop table #mytbl
Here both OUTER APPLY and CROSS APPLY will not increase cardianility estimate.It will always return only one rows.

How to Generate Row number Partition by two column match in sql

Tbl1
---------------------------------------------------------
Id Date Qty ReOrder
---------------------------------------------------------
1 1-1-18 1 3
2 2-1-18 0 3
3 3-1-18 2 3
4 4-1-18 3< >3
5 5-1-18 2 3
6 6-1-18 0 3
7 7-1-18 1 3
8 8-1-18 0 3
---------------------------------------------------------
I want the result like below
---------------------------------------------------------
Id Date Qty ReOrder
---------------------------------------------------------
1 1-1-18 1 3
5 5-1-18 2 3
---------------------------------------------------------
if ReOrder not same with Qty then date will be same upto after reorder=Qty
You can use cumulative approach with row_number() function :
select top (1) with ties *
from (select *, max(case when qty = reorder then 'v' end) over (order by id desc) grp
from table
) t
order by row_number() over(partition by grp order by id);
Unfortunately this will require SQL Server, But you can also do:
select *
from (select *, row_number() over(partition by grp order by id) seq
from (select *, max(case when qty = reorder then 'v' end) over (order by id desc) grp
from table
) t
) t
where seq = 1;

different conditions on different groups

I have a table like this. I would like to get the first row grouped by id where acc1 is not null and if all the rows in the acc1 are null then i would want to get all the rows.
id acc1 acc2
1 null 1
1 1 1
1 1 2
1 2 2
2 null 1
2 null 2
2 null 3
2 null 4
I would like to get an output like this:
id acc1 acc2
1 1 1
2 null 1
2 null 2
2 null 3
2 null 4
Assuming acc1 is unique when not null (for each id):
select t.*
from (select t.*,
rank() over (partition by id
order by (case when acc1 is null then 2 else 1 end), acct1
) as seqnum
from t
) t
where seqnum = 1;
If it is not unique, this just requires a little more work:
select t.*
from (select t.*,
row_number() over (partition by id
order by acct1, acct2
) as seqnum,
count(acct1) over (partition by id) as cnt
from t
) t
where seqnum = 1 or cnt = 0;
This assumes that "first" is based on acct1, acct2. SQL tables are inherently unordered, so you need a column that specifies the ordering.
SELECT *
FROM mytable
QUALIFY Max(acc1) Over (PARTITION BY id) IS NULL -- only NULLs
OR Row_Number() Over (PARTITION BY id -- or the first non-null value
ORDER BY acc1 NULLS LAST) = 1

SQL Rank() function excluding rows

Consider I have the following table.
ID value
1 100
2 200
3 200
5 250
6 1
I have the following query which gives the result as follows. I want to exclude the value 200 from rank function, but still that row has to be returned.
SELECT
CASE WHEN Value = 200 THEN 0
ELSE DENSE_RANK() OVER ( ORDER BY VALUE DESC)
END AS RANK,
ID,
VALUE
FROM #table
RANK ID VALUE
1 5 250
0 2 200
0 3 200
4 1 100
5 6 1
But I want the result as follows. How to achieve it?
RANK ID VALUE
1 5 250
0 2 200
0 3 200
2 1 100
3 6 1
If VAL column is not nullable, taking into account NULL is the last value in ORDER BY .. DESC
select *, dense_rank() over (order by nullif(val,200) desc) * case val when 200 then 0 else 1 end
from myTable
order by val desc;
There is no way to exclude Val in Dense Rank currently ,unless you filter in where clause..that is the reason ,you get below result
RANK ID VALUE
1 5 250
0 2 200
0 3 200
4 1 100
5 6 1
You will need to filter once and then do a union all
;with cte(id,val)
as
(
select 1, 100 union all
select 2, 200 union all
select 3, 200 union all
select 5, 250 union all
select 6, 1 )
select *, dense_rank() over (order by val desc)
from cte
where val<>200
union all
select 0,id,val from cte where val=200
You could split the ranking in to separate queries for the values you want to include/exclude from the ranking and UNION ALL the results like so:
Standalone executable example:
CREATE TABLE #temp ( [ID] INT, [value] INT );
INSERT INTO #temp
( [ID], [value] )
VALUES ( 1, 100 ),
( 2, 200 ),
( 3, 200 ),
( 5, 250 ),
( 6, 1 );
SELECT *
FROM ( SELECT 0 RANK ,
ID ,
value
FROM #temp
WHERE value = 200 -- set rank to 0 for value = 200
UNION ALL
SELECT DENSE_RANK() OVER ( ORDER BY value DESC ) AS RANK ,
ID ,
value
FROM #temp
WHERE value != 200 -- perform ranking on records != 200
) t
ORDER BY value DESC ,
t.ID
DROP TABLE #temp
Produces:
RANK ID value
1 5 250
0 2 200
0 3 200
2 1 100
3 6 1
You can modify the ordering at the end of the statement if required, I set it to produce your desired results.
You can also try this, too:
SELECT ISNULL(R, 0) AS Rank ,t.id ,t.value
FROM tbl1 AS t
LEFT JOIN ( SELECT id ,DENSE_RANK() OVER ( ORDER BY value DESC ) AS R
FROM dbo.tbl1 WHERE value <> 200
) AS K
ON t.id = K.id
ORDER BY t.value DESC
The solution in the original question was actually pretty close. Just adding a partition clause to the dense_rank can do the trick.
SELECT CASE
WHEN VALUE = 200 THEN 0
ELSE DENSE_RANK() OVER(
PARTITION BY CASE WHEN VALUE = 200 THEN 0 ELSE 1 END
ORDER BY VALUE DESC
)
END AS RANK
,ID
,VALUE
FROM #table
ORDER BY VALUE DESC;
The 'partition by' creates separate groups for the dense_rank such that the order is performed on these groups individually. This essentially means you create two ranks at the same time, one for the group without the 200 value and one for the group with only the 200 value. The latter one to be set to 0 in the 'case when'.
Standalone executable example:
DECLARE #table TABLE
(
ID INT NOT NULL PRIMARY KEY
,VALUE INT NULL
)
INSERT INTO #table
(
ID
,VALUE
)
SELECT 1, 100
UNION SELECT 2, 200
UNION SELECT 3, 200
UNION SELECT 5, 250
UNION SELECT 6, 1;
SELECT CASE
WHEN VALUE = 200 THEN 0
ELSE DENSE_RANK() OVER(
PARTITION BY CASE WHEN VALUE = 200 THEN 0 ELSE 1 END
ORDER BY VALUE DESC
)
END AS RANK
,ID
,VALUE
FROM #table
ORDER BY VALUE DESC;
RANK ID VALUE
1 5 250
0 2 200
0 3 200
2 1 100
3 6 1

Any other alternative to write this SQL query

I need to select data base upon three conditions
Find the latest date (StorageDate Column) from the table for each record
See if there is more then one entry for date (StorageDate Column) found in first step for same ID (ID Column)
and then see if DuplicateID is = 2
So if table has following data:
ID |StorageDate | DuplicateTypeID
1 |2014-10-22 | 1
1 |2014-10-22 | 2
1 |2014-10-18 | 1
2 |2014-10-12 | 1
3 |2014-10-11 | 1
4 |2014-09-02 | 1
4 |2014-09-02 | 2
Then I should get following results
ID
1
4
I have written following query but it is really slow, I was wondering if anyone has better way to write it.
SELECT DISTINCT(TD.RecordID)
FROM dbo.MyTable TD
JOIN (
SELECT T1.RecordID, T2.MaxDate,COUNT(*) AS RecordCount
FROM MyTable T1 WITH (nolock)
JOIN (
SELECT RecordID, MAX(StorageDate) AS MaxDate
FROM MyTable WITH (nolock)
GROUP BY RecordID)T2
ON T1.RecordID = T2.RecordID AND T1.StorageDate = T2.MaxDate
GROUP BY T1.RecordID, T2.MaxDate
HAVING COUNT(*) > 1
)PT ON TD.RecordID = PT.RecordID AND TD.StorageDate = PT.MaxDate
WHERE TD.DuplicateTypeID = 2
Try this and see how the performance goes:
;WITH
tmp AS
(
SELECT *,
RANK() OVER (PARTITION BY ID ORDER BY StorageDate DESC) AS StorageDateRank,
COUNT(ID) OVER (PARTITION BY ID, StorageDate) AS StorageDateCount
FROM MyTable
)
SELECT DISTINCT ID
FROM tmp
WHERE StorageDateRank = 1 -- latest date for each ID
AND StorageDateCount > 1 -- more than 1 entry for date
AND DuplicateTypeID = 2 -- DuplicateTypeID = 2
You can use analytic function rank , can you try this query ?
Select recordId from
(
select *, rank() over ( partition by recordId order by [StorageDate] desc) as rn
from mytable
) T
where rn =1
group by recordId
having count(*) >1
and sum( case when duplicatetypeid =2 then 1 else 0 end) >=1