There is a table with Columns as below:
Id : long autoincrement;
timestamp:long;
price:long
Timestamp is given as a unix_time in ms.
Question: what is the average time difference between the records ?
First thought is a sub-query grabbing the record immediately previous:
SELECT timestamp -
(select top 1 timestamp from Table T1 where T1.Id < Table.Id order by Id desc)
FROM Table
Then you can take the average of that:
SELECT AVG(delta)
from (SELECT timestamp -
(select top 1 timestamp from Table T1 where T1.Id < Table.Id order by Id desc) as delta
FROM Table) T
There will probably need to be some handling of the null that results for the first row, but I haven't tested to be sure.
In SQL Server, you could write something like that to get that information:
SELECT
t1.ID, t2.ID,
DATEDIFF(MILLISECOND, t2.PriceTime, test2.PriceTime)
FROM table t1
INNER JOIN table t2 ON t2.ID = t1.ID-1
WHERE t1.ID > (SELECT MIN(ID) FROM table)
and if you're only interested in the AVG across all entries, you could use:
SELECT
AVG(DATEDIFF(MILLISECOND, t2.PriceTime, test2.PriceTime))
FROM table t1
INNER JOIN table t2 ON t2.ID = t1.ID-1
WHERE t1.ID > (SELECT MIN(ID) FROM table)
Basically, you need to join the table with itself, and use "t1.ID = t2.ID-1" to associate item no. 2 in one table with item no. 1 in the other table and then calculate the time difference between the two. In order to avoid accessing item no. 0 which doesn't exist, use the "T1.ID > (SELECT MIN(ID) FROM table)" clause to start from the second item.
Marc
At a guess:
SELECT AVG(timestamp)
I think you need to provide more information in your question for us to help.
If you mean difference between each-other row:
select AVG(x) from (
select a.timestamp - b.timestamp as x
from table a, table b -- this multiplies a*b ) sub
SELECT AVG(T2.Timestamp - T1.TimeStamp)
FROM Table T1
JOIN Table T2 ON T2.ID = T1.ID + 1
try this
Select Avg(E.Timestamp - B.Timestamp)
From Table B Join Table E
On E.Timestamp =
(Select Max(Timestamp)
From Table
Where Timestamp < R.Timestamp)
Related
I have table with names with eomonth history.
I need to join another table that has information about "tests" performed on names:
The result table should show the latest ID and date of performed test but the date of test cannot be greater than the data month:
Any ideas how to perform this?
I am guessing that you want the most recent EOMONTH from the second table for each row in the first table. If that is the correct interpretation, then you can simply use apply:
select t1.*, t2.*
from table1 t1 outer apply
(select top (1) t2.*
from table2 t2
where t2.test_id = t1.test_id and t2.eomonth <= t1.test_date
order by t2.eomonth desc
) t2;
This join works perfectly:
from table1 a
left join table2 b on a.name = b.name and a.eomonth >= b.id_date and a.eomonth < LAG(b.id_date,1,'3000-01-01') OVER (PARTITION BY name ORDER BY b.id_date desc)
I have a table having multiple negative and positive values, i want to delete only those number of records from table which are having negative values and have the same positive values . I'm not sure how to explain this scenario...
I will give a brief example-
I have a table with 6 records in which 2 records are with negative value and 4 record with positive
Name | number
A | 1
A |-1
A | 1
A |-1
A | 1
A | 1
So here i want to delete equal number of records of negative value and positive value
so my output should be
Name | Number
A | 1
A | 1
By using Row_number
;WITH CTE AS (
select *,ROW_NUMBER()OVER(PARTITION BY number ORDER BY (SELECT NULL)) -1 RN from Table1 )
Select Name, number from CTE WHERE RN NOT IN (1,0)
The following query assumes that your table has either a column called id which is either a primary key or some other means to order your records. Without any order, your question cannot be answered, and in fact the data sample you showed us would have no meaning, since internally records have no order in a SQL database.
WITH cte1 AS (
SELECT t1.id, t1.number, SUM(t2.number) as sum
FROM yourTable t1
INNER JOIN yourTable t2 on t1.id >= t2.id
GROUP BY t1.id, t1.number
)
WITH cte2 AS (
SELECT MAX(id) AS cutoff
FROM cte1
WHERE sum = 0
)
SELECT t.*
FROM yourTable t
WHERE t.id > (SELECT cutoff FROM cte2)
Note that I used the old school way of computing a running sum because you never told us the version of SQL Server which you are using. Hence, I didn't want to make assumptions about what you have available.
declare #negvalrecs int = (select COUNT(*) from tab where Number < 0)
delete
from tab
where Number < 0
delete top (#negvalrecs)
from tab
where Number > 0
Thanks for all your inputs!
I have a solution for it. We will be needing row number function for it.
--Providing row number to rows
select *,row_number () over (partition by name,number order by name) R into #1 from Table
--Taking negative values
select * into #2 from #1 where number<0
--Now Deleting those records from the main table by joining this table
delete #1 from #1 a inner join #2 b on a.name=b.name and a.number=b.number and a.r<=b.r
delete #1 from #1 a inner join #2 b on a.name=b.name and a.number=-(b.number) and a.r<=b.r
Hope it helps!
I recently encountered a similar problem and this is how I resolved it.
I also had records in table where there we no negatives for a given name the union all is to bring such records.
SELECT t1.name, t1.number
FROM table t1
LEFT OUTER JOIN
(SELECT name, number FROM table where number < 0) t2
ON
t1.name = t2.name and t1.number = t2.number
WHERE t1.number > 0 and t2.number IS NOT NULL
UNION ALL
SELECT t1.name, t1.number
FROM table t1
LEFT OUTER JOIN
(SELECT name, number FROM table where number < 0) t2
ON
t1.name = t2.name
WHERE t1.number > 0 and t2.number IS NULL;`
Try this,
delete from table_name
where substring(ltrim(rtrim(number)),1,1)='-'
I have a table with 3 values.
ID AuditDateTime UpdateType
12 12-15-2015 18:09 1
45 12-04-2015 17:41 0
75 12-21-2015 04:26 0
12 12-17-2015 07:43 0
35 12-01-2015 05:36 1
45 12-15-2015 04:35 0
I'm trying to return only records where the UpdateType has changed from AuditDateTime based on the IDs. So in this example, ID 12 changes from the 12-15 entry to the 12-17 entry. I would want that record returned. There will be multiple instances of ID 12, and I need all records returned where an ID's UpdateType has changed from its previous entry. I tried adding a row_number but it didn't insert sequentially because the records are not in the table in order. I've done a ton of searching with no luck. Any help would be greatly appreciated.
By using a CTE it is possible to find the previous record based upon the order of the AuditDateTime
WITH CTEData AS
(SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY AuditDateTime) [ROWNUM], *
FROM #tmpTable)
SELECT A.ID, A.AuditDateTime, A.UpdateType
FROM CTEData A INNER JOIN CTEData B
ON (A.ROWNUM - 1) = B.ROWNUM AND
A.ID = B.ID
WHERE A.UpdateType <> B.UpdateType
The Inner Join back onto the CTE will give in one query both the current record (Table Alias A) and previous row (Table Alias B).
This should do what you're trying to do I believe
SELECT
T1.ID,
T1.AuditDateTime,
T1.UpdateType
FROM
dbo.My_Table T1
INNER JOIN dbo.My_Table T2 ON
T2.ID = T1.ID AND
T2.UpdateType <> T1.UpdateType AND
T2.AuditDateTime < T1.AuditDateTime
LEFT OUTER JOIN dbo.My_Table T3 ON
T3.ID = T1.ID AND
T3.AuditDateTime < T1.AuditDateTime AND
T3.AuditDateTime > T2.AuditDateTime
WHERE
T3.ID IS NULL
Alternatively:
SELECT
T1.ID,
T1.AuditDateTime,
T1.UpdateType
FROM
dbo.My_Table T1
INNER JOIN dbo.My_Table T2 ON
T2.ID = T1.ID AND
T2.UpdateType <> T1.UpdateType AND
T2.AuditDateTime < T1.AuditDateTime
WHERE
NOT EXISTS
(
SELECT *
FROM
dbo.My_Table T3
WHERE
T3.ID = T1.ID AND
T3.AuditDateTime < T1.AuditDateTime AND
T3.AuditDateTime > T2.AuditDateTime
)
The basic gist of both queries is that you're looking for rows where an earlier row had a different type and no other rows exist between the two rows (hence, they're sequential). Both queries are logically identical, but might have differing performance.
Also, these queries assume that no two rows will have identical audit times. If that's not the case then you'll need to define what you expect to get when that happens.
You can use the lag() window function to find the previous value for the same ID. Now you can pick only those rows that introduce a change:
select *
from (
select lag(UpdateType) over (
partition by ID
order by AuditDateTime) as prev_updatetype
, *
from YourTable
) sub
where prev_updatetype <> updatetype
Example at SQL Fiddle.
I apologize if the title seems absurd and lack information I am trying to explain the situation through following example:
Consider the following table-
ID Event Time
---------------------
1 EventA ta
1 EventB tx
2 EventB ty
1 EventC tb
2 EventC to
I wish to select the ID such that there is an EventC after(based on Time) any instance of EventB.
I could think of the following query:
select ID from TabET where
((select TIME from TabET where Event = EventC order by TIME desc fetch first row only)
>
(select TIME from TabET where Event = EventB order by TIME desc fetch first row only))
I am looking for a better approach and alternative as the table in reality is a very big table and this query is just a subquery inside a big query to satisfy a condition.
Edit
The ID is not unique. The problem is to identify the IDs for whcich there is an EventC after(based on TIME) an EventB
You can use a self join:
select distinct t1.ID
from table t1
join table t2 on
t1.ID = t2.ID and
t1.Event = 'EventB' and
t2.Event = 'EventC' and
t2.Time > t1.Time
Another approach:
with latest_times as (
select id, max(time) as time from table
where Event='EventC'
group by id
)
select t1.ID from table t1
join latest_times on
t1.id = latest_times.id and
t1.Event = 'EventB' and
latest_times.time > t1.time
Hope the title makes some kind of sense - I'd basically like to do a nested select, based on a value in the original select, like so:
SELECT MAX(iteration) AS maxiteration,
(SELECT column
FROM table
WHERE id = 223652
AND iteration = maxiteration)
FROM table
WHERE id = 223652;
I get an ORA-00904 invalid identifier error.
Would really appreciate any advice on how to return this value, thanks!
It looks like this should be rewritten with a where clause:
select iteration,
col
from tbl
where id = 223652
and iteration = (select max(iteration) from tbl where id = 223652);
You can circumvent the problem alltogether by placing the subselect in an INNER JOIN of its own.
SELECT t.iteration
, t.column
FROM table t
INNER JOIN (
SELECT id, MAX(iteration) AS iteration
FROM table
WHERE id = 223652
) tm ON tm.id = t.id AND tm.iteration = t.iteration
Since you're using Oracle, I'd suggest using analytic functions for this:
SELECT * FROM (
SELECT col,
iteration,
row_number() over (partition by id order by iteration desc) rn
FROM tab
WHERE id = 223652
) WHERE rn = 1
do it like this:
with maxiteration as
(
SELECT MAX(iteration) AS maxiteration
FROM table
WHERE id = 223652
)
select
column,
iteration
from
table
where
id = 223652
AND iteration = maxiteration
;
Not 100% sure on Oracle syntax, but isn't it something like:
select iteration, column from table where id = 223652 order by iteration desc limit 1
I would approach this problem in a slightly different way. You're basically looking for the row that has no other iterations greater than it. There are at least 3 ways I can think of to do this:
SELECT
T1.iteration AS maxiteration,
T1.column
FROM
Table T1
WHERE
T1.id = 223652 AND
NOT EXISTS
(
SELECT *
FROM Table T2
WHERE
T2.id = 223652 AND
T2.iteration > T1.iteration
)
Or...
SELECT
T1.iteration AS maxiteration,
T1.column
FROM
Table T1
LEFT OUTER JOIN Table T2 ON
T2.id = T1.id AND
T2.iteration > T1.iteration
WHERE
T1.id = 223652 AND
T2.id IS NULL
Or...
SELECT
T1.iteration AS maxiteration,
T1.column
FROM
Table T1
INNER JOIN (SELECT id, MAX(iteration) AS maxiteration FROM Table T2 GROUP BY id) SQ ON
SQ.id = T1.id AND
SQ.maxiteration = T1.iteration
WHERE
T1.id = 223652
EDIT: I didn't see the ORA error the first time reading the question and it wasn't tagged as Oracle specific. I think that there may be some differences in the syntax and use of aliases in Oracle, so you may need to tweak some of the above queries.
The Oracle error is telling you that it doesn't know what maxiteration is, because the column alias isn't available yet inside the subquery. You need to refer to it by the table alias and column name instead of the column alias I believe.
You do something like
select maxiteration,column from table a join (select max(iteration) as maxiteration from table where id=1) b using (id) where b.maxiteration=a.iteration;
This could of course return multiple rows for one maxiteration unless your table has a constraint against it.