I have a table:
| id | Number |Address
| -----| ------------|-----------
| 1 | 0 | NULL
| 1 | 1 | NULL
| 1 | 2 | 50
| 1 | 3 | NULL
| 2 | 0 | 10
| 3 | 1 | 30
| 3 | 2 | 20
| 3 | 3 | 20
| 4 | 0 | 75
| 4 | 1 | 22
| 4 | 2 | 30
| 5 | 0 | NULL
I need to get: the NUMBER of the last ADDRESS change for each ID.
I wrote this select:
select dh.id, dh.number from table dh where dh =
(select max(min(t.history)) from table t where t.id = dh.id group by t.address)
But this select not correctly handling the case when the address first changed, and then changed to the previous value. For example id=1: group by return:
| Number |
| -------- |
| NULL |
| 50 |
I have been thinking about this select for several days, and I will be happy to receive any help.
You can do this using row_number() -- twice:
select t.id, min(number)
from (select t.*,
row_number() over (partition by id order by number desc) as seqnum1,
row_number() over (partition by id, address order by number desc) as seqnum2
from t
) t
where seqnum1 = seqnum2
group by id;
What this does is enumerate the rows by number in descending order:
Once per id.
Once per id and address.
These values are the same only when the value is 1, which is the most recent address in the data. Then aggregation pulls back the earliest row in this group.
I answered my question myself, if anyone needs it, my solution:
select * from table dh1 where dh1.number = (
select max(x.number)
from (
select
dh2.id, dh2.number, dh2.address, lag(dh2.address) over(order by dh2.number asc) as prev
from table dh2 where dh1.id=dh2.id
) x
where NVL(x.address, 0) <> NVL(x.prev, 0)
);
Original Table
Id | Time | Status
------------------
1 | 5 | T
1 | 6 | F
2 | 3 | F
1 | 2 | F
2 | 4 | T
3 | 7 | F
2 | 3 | T
3 | 1 | F
4 | 7 | H
4 | 6 | S
4 | 5 | F
4 | 4 | T
5 | 5 | S
5 | 6 | F
Expected Table
Id | Time | Status
------------------
1 | 6 | F
3 | 7 | F
4 | 5 | F
I want all the distinct ids who have status as F but time should be maximum, if for any id status is T for given maximum time then that id should not be picked. Also only those ids should be picked who have at-least one T. For e.g 4 will not be picked at it doesn't have any 'T' as status.
Please help in writing the SQL query.
You can use EXISTS and NOT EXISTS in the WHERE clause:
select t.*
from tablename t
where t.status = 'F'
and exists (select 1 from tablename where id = t.id and status = 'T')
and not exists (
select 1
from tablename
where id = t.id and status in ('F', 'T') and time > t.time
)
See the demo.
Results:
| Id | Time | Status |
| --- | ---- | ------ |
| 1 | 6 | F |
| 4 | 5 | F |
Try the below way -
select * from tablename t
where time = (select max(time) from tablename t1 where t.id=t1.id and Status='F')
and Status='F'
the following should work
select id,max(time) as time,status
from table
where status='F'
group by id,status
select id, max(time), status
from stuff s
where status = 'F'
and id not in (
select id
from stuff s2
where s2.id = s.id
and s2.time > s.time
and s2.status = 'T')
group by id, status;
You can see the Fiddle here.
As I understand it, you want to find the highest time for each ID (max(time)) where the status is F, but only if there isn't a later record where the status is 'T'. The sub query filters out records where there exists a later record where the status is T.
WITH MAX_TIME_ID AS (
SELECT
ID
,MAX(TIME) AS MAX_TIME
GROUP BY
ID
)
SELECT
O.*
FROM
ORIGINAL_TABLE O
INNER JOIN
MAX_TIME_ID MAX
ON
O.ID = MAX.ID
WHERE
O.STATUS = 'F'
The CTE will find the max time for each ID and the inner join with the where clause on the status will select it only if the latest is 'F'.
I would just use window functions:
select t.*
from (select t.*
row_number() over (partition by id order by time desc) as seqnum,
sum(case when status = 'T' then 1 else 0 end) over (partition by id) as num_t
from t
) t
where num_t > 0 and
seqnum = 1 and status = 'F';
There is a another fun way to do this just with aggregation:
select id, max(time) as time, 'F' as status
from t
group by id
having sum(case when status = 'T' then 1 else 0 end) > 0 and
max(time) = max(case when status 'F' then time end);
I have a simple scenario wherein, a table stores data about which card(s) a users uses and if those cards are registered (exist) in the system. I've applied ROW_NUMBER to group them too
SELECT User, CardId, CardExists, ROW_NUMBER() OVER (PARTITION BY User) AS RowNum From dbo.CardsInfo
User | CardID | CardExists | RowNum
-------------------------------------
A | 1 | 0 | 1
A | 2 | 1 | 2
A | 3 | 1 | 3
---------------------------------
B | 4 | 0 | 1
B | 5 | 0 | 2
B | 6 | 0 | 3
B | 7 | 0 | 4
---------------------------------
C | 8 | 1 | 1
C | 9 | 0 | 2
C | 10 | 1 | 3
Now in the above, I need to filter out User cards based on the two rules below
If in the cards registered with a user, multiple cards exist in the system, then take first one. So, for user A, CardID 2 will be returned and for User C it'll return CardID = 8
Othwerwise, if no card is existing (registered) for the user in the system, then just take the first one. So, for user B, it should return CardID = 4
Thus, final returned set should be -
User | CardID | CardExists | RowNum
-------------------------------------
A | 2 | 1 | 2
---------------------------------
B | 4 | 0 | 1
---------------------------------
C | 8 | 1 | 1
How can I do this filteration in SQL?
Thanks
You can use:
SELECT ci.*
FROM (SELECT User, CardId, CardExists,
ROW_NUMBER() OVER (PARTITION BY User ORDER BY CardExists DESC, CardId) AS RowNum
FROM dbo.CardsInfo ci
) ci
WHERE seqnum = 1;
You can also do this with aggregation:
select user,
max(cardexists) as cardexists,
coalesce(min(case when cardexists = 1 then cardid end),
min(card(cardid)
) as cardid
from cardsinfo
group by user;
Or, if you have a separate users table:
select ci.*
from users u cross apply
(select top (1) ci.*
from cardinfo ci
where ci.user = u.user
order by ci.cardexists desc, cardid asc
) ci
Assume I have this table:
+----+-------+
| id | value |
+----+-------+
| 1 | 5 |
| 2 | 4 |
| 3 | 1 |
| 4 | NULL |
| 5 | NULL |
| 6 | 14 |
| 7 | NULL |
| 8 | 0 |
| 9 | 3 |
| 10 | NULL |
+----+-------+
I want to write a query that will replace any NULL value with the last value in the table that was not null in that column.
I want this result:
+----+-------+
| id | value |
+----+-------+
| 1 | 5 |
| 2 | 4 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 14 |
| 7 | 14 |
| 8 | 0 |
| 9 | 3 |
| 10 | 3 |
+----+-------+
If no previous value existed, then NULL is OK. Ideally, this should be able to work even with an ORDER BY. So for example, if I ORDER BY [id] DESC:
+----+-------+
| id | value |
+----+-------+
| 10 | NULL |
| 9 | 3 |
| 8 | 0 |
| 7 | 0 |
| 6 | 14 |
| 5 | 14 |
| 4 | 14 |
| 3 | 1 |
| 2 | 4 |
| 1 | 5 |
+----+-------+
Or even better if I ORDER BY [value] DESC:
+----+-------+
| id | value |
+----+-------+
| 6 | 14 |
| 1 | 5 |
| 2 | 4 |
| 9 | 3 |
| 3 | 1 |
| 8 | 0 |
| 4 | 0 |
| 5 | 0 |
| 7 | 0 |
| 10 | 0 |
+----+-------+
I think this might involve some kind of analytic function - somehow partitioning over the value column - but I'm not sure where to look.
You can use a running sum to set groups and use max to fill in the null values.
select id,max(value) over(partition by grp) as value
from (select id,value,sum(case when value is not null then 1 else 0 end) over(order by id) as grp
from tbl
) t
Change the over() clause to order by value desc to get the second result in the question.
The best way has been covered by Itzik Ben-Gan here:The Last non NULL Puzzle
Below is a solution which for 10 million rows and completes around in 20 seconds on my system
SELECT
id,
value1,
CAST(
SUBSTRING(
MAX(CAST(id AS binary(4)) + CAST(value1 AS binary(4)))
OVER (ORDER BY id
ROWS UNBOUNDED PRECEDING),
5, 4)
AS int) AS lastval
FROM dbo.T1;
This solution assumes your id column is indexed
You can also try using correlated subquery
select id,
case when value is not null then value else
(select top 1 value from table
where id < t.id and value is not null order by id desc) end value
from table t
Result :
id value
1 5
2 4
3 1
4 1
5 1
6 14
7 14
8 0
9 3
10 3
If the NULLs are scattered I use a WHILE loop to fill them in
However if the NULLs are in longer consecutive strings there are faster ways to do it.
So here's one approach:
First find a record that we want to update. It has NULL in this record and no NULL in the prior record
SELECT C.VALUE, N.ID
FROM TABLE C
INNER JOIN TABLE N
ON C.ID + 1 = N.ID
WHERE C.VALUE IS NOT NULL
AND N.VALUE IS NULL;
Use that to update: (bit hazy on this syntax but you get the idea)
UPDATE N
SET VALUE = C.Value
FROM TABLE C
INNER JOIN TABLE N
ON C.ID + 1 = N.ID
WHERE C.VALUE IS NOT NULL
AND N.VALUE IS NULL;
.. now just keep doing it till you run out of rows
-- This is needed to set ##ROWCOUNT to non zero
SELECT 1;
WHILE ##ROWCOUNT <> 0
BEGIN
UPDATE N
SET VALUE = C.Value
FROM TABLE C
INNER JOIN TABLE N
ON C.ID + 1 = N.ID
WHERE C.VALUE IS NOT NULL
AND N.VALUE IS NULL;
END
The other way is to use a similiar query to get a range of id's to update. This works much faster if your NULLS are usually against consecutive id's
Here is the one simple approach using OUTER APPLY
CREATE TABLE #table(id INT, value INT)
INSERT INTO #table VALUES
(1,5),
(2,4),
(3,1),
(4,NULL),
(5,NULL),
(6,14),
(7,NULL),
(8,0),
(9,3),
(10,NULL)
SELECT t.id, ISNULL(t.value, t3.value) value
FROM #table t
OUTER APPLY(SELECT id FROM #table WHERE id = t.id AND VALUE IS NULL) t2
OUTER APPLY(SELECT TOP 1 value
FROM #table WHERE id <= t2.id AND VALUE IS NOT NULL ORDER BY id DESC) t3
OUTPUT:
id VALUE
---------
1 5
2 4
3 1
4 1
5 1
6 14
7 14
8 0
9 3
10 3
Using this sample data:
if object_id('tempdb..#t1') is not null drop table #t1;
create table #t1 (id int primary key, [value] int null);
insert #t1 values(1,5),(2,4),(3,1),(4,NULL),(5,NULL),(6,14),(7,NULL),(8,0),(9,3),(10,NULL);
I came up with:
with x(id, [value], grouper) as (
select *, row_number() over (order by id)-sum(iif([value] is null,1,0)) over (order by id)
from #t1)
select id, min([value]) over (partition by grouper)
from x;
I noticed, however, that Vamsi Prabhala beat me to it... My solution is identical to what he posted. (arghhhh!). So I thought I'd try a recursive solution. Here's a pretty efficient use of a recursive cte (provided that ID is indexed):
with sorted as (select *, seqid = row_number() over (order by id) from #t1),
firstRecord as (select top(1) * from #t1 order by id),
prev as
(
select t.id, t.[value], lastid = 1, lastvalue = null
from sorted t
where t.id = 1
union all
select t2.id, t2.[value], lastid+1, isnull(prev.[value],lastvalue)
from sorted t2
join prev on t2.id = prev.lastid+1
)
select id, [value]=isnull([value],lastvalue)--, *
from prev;
Normally I don't like recursive cte's (rCte for short) but in this case it offered an elegant solution and was faster than using the window aggregate function (sum over, min over...). Note the execution plans, the rcte on the bottom. The rCTE get's it done with two index seeks, one of which is for just one row. Unlike the window aggregate solution, the rcte does not require a sort. Running this with statistics io on; the rcte produces much less IO.
All this said, don't use either of these solutions, What the TheGameiswar posted will perform the best by far. His solution on a properly indexed id column would be lightening fast.
Following UPDATE statement can be used, please test it before use
update #table
set value = newvalue
from (
select
s.id, s.value,
(select top 1 t.value from #table t where t.id <= s.id and t.value is not null order by t.id desc) as newvalue
from #table S
) u
where #table.id = u.id and #table.value is null
stop worrying..here's the answer for you :)
SELECT *
INTO #TempIsNOtNull
FROM YourTable
WHERE value IS NOT NULL
SELECT *
INTO #TempIsNull
FROM YourTable
WHERE value IS NULL
UPDATE YourTable
SEt YourTable.value = UpdateDtls.value
FROM YourTable
JOIN (
SELECT OuterTab1.id,
#TempIsNOtNull.value
FROM #TempIsNull OuterTab1
CROSS JOIN #TempIsNOtNull
WHERE OuterTab1.id - #TempIsNOtNull.id > 0
AND (OuterTab1.id - #TempIsNOtNull.id) = ( SELECT TOP 1
OuterTab1.id - #TempIsNOtNull.id
FROM #TempIsNull InnerTab
CROSS JOIN #TempIsNOtNull
WHERE OuterTab1.id - #TempIsNOtNull.id > 0
AND OuterTab1.id = InnerTab.id
ORDER BY (OuterTab1.id - #TempIsNOtNull.id) ASC) ) AS UpdateDtls
ON (YourTable.id = UpdateDtls.id)
I have 2 tables having schema as given below
EmployeeDetails - (employeeID,timestamp,status)
EmployeeActivity - (employeedID, timestamp, activity)
Status field is either 0 or 1
What I want to do is, find the timestamp when status goes from 1 to 0. Use this date as parameter in finding activity done after this date from table 2.
I am sorry I am not able to provide a sample query at this point. Since I am not sure whether this can be done using a single query or will I need PL/SQL.
Any help would be appreciated.
Thanks
EDIT
Sample Data
Table 1
employeeID | timestamp | status
1 | 01-NOV-13 | 1
2 | 01-NOV-13 | 1
1 | 02-NOV-13 | 0
2 | 02-NOV-13 | 1
1 | 03-NOV-13 | 0
2 | 03-NOV-13 | 0
Table 2
employeeID | timestamp | activity
1 | 01-NOV-13 | 1
2 | 01-NOV-13 | 1
1 | 02-NOV-13 | 0
2 | 02-NOV-13 | 1
1 | 03-NOV-13 | 1
2 | 03-NOV-13 | 0
Result
employeeID | timestamp | activity
1 | 03-NOV-13 | 1
This is the output since EmployeeId=1 has activity when its status is 0.
WITH previous_statuses AS (
SELECT employeeID,
timestamp_val,
status,
LAG( status ) OVER ( PARTITION BY employeeID ORDER BY timestamp_val ) AS previous_status
FROM employeeDetails
),
changed_statuses AS (
SELECT employeeID,
timestamp_val
FROM previous_statuses
WHERE status = 0
AND previous_status = 1
)
SELECT a.employeeID,
a.timestamp_val,
a.activity
FROM employeeActivity a
INNER JOIN
changed_statuses s
ON ( a.employeeID = s.employeeID
AND a.timestamp_val = s.timestamp_val);
SQLFIDDLE