I have the following table:
RowId, UserId, Date
1, 1, 1/1/01
2, 1, 2/1/01
3, 2, 5/1/01
4, 1, 3/1/01
5, 2, 9/1/01
I want to get the latest records based on date and per UserId but as a part of the following query (due to a reason I cannot change this query as this is auto generated by a tool but I can write pass any thing starting with AND...):
SELECT RowId, UserId, Date
FROM MyTable
WHERE 1 = 1
AND (
// everything which needs to be done goes here . . .
)
I have tried similar query, but get an error:
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.
EDIT: Database is Sql Server 2008
You could use a NOT EXISTS condition:
SELECT RowId, UserId, Date
FROM MyTable
WHERE 1 = 1
AND NOT EXISTS (
SELECT *
FROM MyTable AS t
WHERE t.UserId = MyTable.UserId
AND t.Date > MyTable.Date
)
;
Note that if a user has more than one row with the same latest Date value, the query will return all such entries. If necessary, you can modify the subquery's condition slightly to make sure only one row is returned:
WHERE t.UserId = MyTable.UserId
AND (t.Date > MyTable.Date
OR t.Date = MyTable.Date AND t.RowId > MyTable.RowId
)
With the above condition, if two or more rows with the same Date exist for the same user, the one with the greater RowId value will be returned.
Assuming you have the ability to modify anything within the AND clause you can do a query like this if you are using TSQL
SELECT RowId, UserId, [Date]
FROM #myTable
WHERE 1 = 1
AND (
RowId IN (
SELECT D.RowId
FROM (
SELECT DISTINCT MAX(RowId) AS RowId, UserId, MAX([Date]) AS [Date]
FROM #myTable
GROUP BY UserId
) AS D
)
)
Try:
SELECT RowId, UserId, Date
FROM MyTable
WHERE 1 = 1
AND EXISTS
(SELECT 1
FROM (SELECT UserId, MAX(Date) MaxDate
FROM MyTable
GROUP BY UserId) m
WHERE m.UserId = MyTable.UserId and m.MaxDate = MyTable.Date)
SQLFiddle here.
Assuming that RowID is an identity column:
SELECT t1.RowId, t1.UserId, t1.Date
FROM MyTable t1
WHERE 1 = 1
AND t1.RowID IN (
SELECT TOP 1 t2.RowID
FROM MyTable t2
WHERE t1.UserId = t2.UserId
AND t2.Date = (SELECT MAX(t3.Date) FROM MyTable t3
WHERE t2.UserID = t3.UserId)
)
Demo
Related
I have the data in Initial format:
STEP 1: To find out the users having more than 1 record and show those records. This was achieved using the below.
SELECT ID,
USER,
STATUS
FROM TABLE
WHERE USER in
(SELECT USER
FROM TABLE
GROUP BY USER
HAVING COUNT(*) > 1)
*STEP 2: From the above set of records find out records for which all the values are either 1 or 2. SO data should be something like:
Can I get some suggestions to how to achieve that. Note status is NVARCHAR hence aggregate functions can't be used.
The simplest thing is to check that the status is the same in your subquery. Assuming that status only takes on the values 1 and 2:
SELECT t.ID, t.USER, t.STATUS
FROM TABLE
WHERE t.USER IN (SELECT t2.USER
FROM TABLE t2
GROUP BY t2.USER
HAVING COUNT(*) > 1 AND
MIN(t2.status) = MAX(t2.status)
);
If there are other status values and you particularly care about 1 and 2, you would use:
SELECT t.ID, t.USER, t.STATUS
FROM TABLE
WHERE t.USER IN (SELECT t2.USER
FROM TABLE t2
GROUP BY t2.USER
HAVING COUNT(*) > 1 AND
MIN(t2.status) = MAX(t2.status) AND
MIN(t2.status) IN (1, 2)
);
Please check if this helps
SELECT ID,
[USER],
[STATUS]
FROM TABLE
WHERE [USER] in
(SELECT [USER]
FROM TABLE
GROUP BY [USER]
HAVING COUNT([USER]) > 1 AND ((MIN(STATUS) != MAX(STATUS) AND COUNT(STATUS) > 2) OR (MIN(STATUS) = MAX(STATUS))))
I have a little sql query, like so
SELECT * FROM table
This returns a bunch of results, i output the following fields:
ID
UserID
Amount
Date
What i want to do is get the most recent entry from each UserID ( based on ID ), then if the amount is 0 do not return ANY results from that UserID.
select t1.*
from your_table t1
join
(
select userid, max(date) as mdate
from your_table
group by userid
having sum(case when amount = 0 then 1 else 0 end) = 0
) t2 on t1.userid = t2.userid and t1.date = t2.mdate
In the subquery you group by the user and select only those having no amount of zero. In that select you use max(date) as mdate to get the latest date for each user.
That subquery can be joined to the original table to get the complete record and not just the userid.
try this
WITH cte AS
(
SELECT
MAX(ID) OVER (PARTITION BY UserID) MaxIDForUserID,
ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY ID DESC) rn,
UserID,
Amount,
Date
FROM TableName
)
SELECT * FROM cte WHERE rn = 1 AND Amount != 0
So I have data like this:
UserID CreateDate
1 10/20/2013 4:05
1 10/20/2013 4:10
1 10/21/2013 5:10
2 10/20/2012 4:03
I need to group by each user get the average time between CreateDates. My desired results would be like this:
UserID AvgTime(minutes)
1 753.5
2 0
How can I find the difference between CreateDates for all records returned for a User grouping?
EDIT:
Using SQL Server 2012
Try this:
SELECT A.UserID,
AVG(CAST(DATEDIFF(MINUTE,B.CreateDate,A.CreateDate) AS FLOAT)) AvgTime
FROM #YourTable A
OUTER APPLY (SELECT TOP 1 *
FROM #YourTable
WHERE UserID = A.UserID
AND CreateDate < A.CreateDate
ORDER BY CreateDate DESC) B
GROUP BY A.UserID
This approach should aslo work.
Fiddle demo here:
;WITH CTE AS (
Select userId, createDate,
row_number() over (partition by userid order by createdate) rn
from Table1
)
select t1.userid,
isnull(avg(datediff(second, t1.createdate, t2.createdate)*1.0/60),0) AvgTime
from CTE t1 left join CTE t2 on t1.UserID = t2.UserID and t1.rn +1 = t2.rn
group by t1.UserID;
Updated: Thanks to #Lemark for pointing out number of diff = recordCount - 1
since you're using 2012 you can use lead() to do this
with cte as
(select
userid,
(datediff(second, createdate,
lead(CreateDate) over (Partition by userid order by createdate)
)/60) datdiff
From table1
)
select
userid,
avg(datdiff)
from cte
group by userid
Demo
Something like this:
;WITH CTE AS
(
SELECT
ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY CreateDate) RN,
UserID,
CreateDate
FROM Tbl
)
SELECT
T1.UserID,
AVG(DATEDIFF(mi, ISNULL(T2.CreateDate, T1.CreateDate), T1.CreateDate)) AvgTime
FROM CTE T1
LEFT JOIN CTE T2
ON T1.UserID = T2.UserID
AND T1.RN = T2.RN - 1
GROUP BY T1.UserID
With SQL 2012 you can use the ROW_NUMBER function and self-join to find the "previous" row in each group:
WITH Base AS
(
SELECT
ROW_NUMBER() OVER (PARTITION BY UserID ORDER BY CreateDate) RowNum,
UserId,
CreateDate
FROM Users
)
SELECT
B1.UserID,
ISNULL(
AVG(
DATEDIFF(mi,B2.CreateDate,B1.CreateDate) * 1.0
)
,0) [Average]
FROM Base B1
LEFT JOIN Base B2
ON B1.UserID = B2.UserID
AND B1.RowNum = B2.RowNum + 1
GROUP BY B1.UserId
Although I get a different answer for UserID 1 - I get an average of (5 + 1500) / 2 = 752.
This only works in 2012. You can use the LEAD analytic function:
CREATE TABLE dates (
id integer,
created datetime not null
);
INSERT INTO dates (id, created)
SELECT 1 AS id, '10/20/2013 4:05' AS created
UNION ALL SELECT 1, '10/20/2013 4:10'
UNION ALL SELECT 1, '10/21/2013 5:10'
UNION ALL SELECT 2, '10/20/2012 4:03';
SELECT id, isnull(avg(diff), 0)
FROM (
SELECT id,
datediff(MINUTE,
created,
LEAD(created, 1, NULL) OVER(partition BY id ORDER BY created)
) AS diff
FROM dates
) as diffs
GROUP BY id;
http://sqlfiddle.com/#!6/4ce89/22
Table Essentially looks like:
Serial-ID, ID, Date, Data, Data, Data, etc.
There can be Multiple Rows for the Same ID. I'd like to create a view of this table to be used in Reports that only shows the most recent entry for each ID. It should show all of the columns.
Can someone help me with the SQL select? thanks.
There's about 5 different ways to do this, but here's one:
SELECT *
FROM yourTable AS T1
WHERE NOT EXISTS(
SELECT *
FROM yourTable AS T2
WHERE T2.ID = T1.ID AND T2.Date > T1.Date
)
And here's another:
SELECT T1.*
FROM yourTable AS T1
LEFT JOIN yourTable AS T2 ON
(
T2.ID = T1.ID
AND T2.Date > T1.Date
)
WHERE T2.ID IS NULL
One more:
WITH T AS (
SELECT *, ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Date DESC) AS rn
FROM yourTable
)
SELECT * FROM T WHERE rn = 1
Ok, i'm getting carried away, here's the last one I'll post(for now):
WITH T AS (
SELECT ID, MAX(Date) AS latest_date
FROM yourTable
GROUP BY ID
)
SELECT yourTable.*
FROM yourTable
JOIN T ON T.ID = yourTable.ID AND T.latest_date = yourTable.Date
I would use DISTINCT ON
CREATE VIEW your_view AS
SELECT DISTINCT ON (id) *
FROM your_table a
ORDER BY id, date DESC;
This works because distinct on suppresses rows with duplicates of the expression in parentheses. DESC in order by means the one that normally sorts last will be first, and therefor be the one that shows in the result.
https://www.postgresql.org/docs/10/static/sql-select.html#SQL-DISTINCT
This seems like a good use for correlated subqueries:
CREATE VIEW your_view AS
SELECT *
FROM your_table a
WHERE date = (
SELECT MAX(date)
FROM your_table b
WHERE b.id = a.id
)
Your date column would need to uniquely identify each row (like a TIMESTAMP type).
I have a requirement where I need to get data from the previous row to use in a calculation to give a status to the current row. It's a history table. The previous row will let me know if a data has changed in a date field.
I've looked up using cursors and it seems a little complicated. Is this the best way to go?
I've also tried to assgin a value to a new field...
newField =(Select field1 from Table1 where "previous row") previous row is where I seem to get stuck. I can't figure out how to select the row beneath the current row.
I'm using SQL Server 2005
Thanks in advance.
-- Test data
declare #T table (ProjectNumber int, DateChanged datetime, Value int)
insert into #T
select 1, '2001-01-01', 1 union all
select 1, '2001-01-02', 1 union all
select 1, '2001-01-03', 3 union all
select 1, '2001-01-04', 3 union all
select 1, '2001-01-05', 4 union all
select 2, '2001-01-01', 1 union all
select 2, '2001-01-02', 2
-- Get CurrentValue and PreviousValue with a Changed column
;with cte as
(
select *,
row_number() over(partition by ProjectNumber order by DateChanged) as rn
from #T
)
select
C.ProjectNumber,
C.Value as CurrentValue,
P.Value as PreviousValue,
case C.Value when P.Value then 0 else 1 end as Changed
from cte as C
inner join cte as P
on C.ProjectNumber = P.ProjectNumber and
C.rn = P.rn + 1
-- Count the number of changes per project
;with cte as
(
select *,
row_number() over(partition by ProjectNumber order by DateChanged) as rn
from #T
)
select
C.ProjectNumber,
sum(case C.Value when P.Value then 0 else 1 end) as ChangeCount
from cte as C
inner join cte as P
on C.ProjectNumber = P.ProjectNumber and
C.rn = P.rn + 1
group by C.ProjectNumber
This really depends on what tells you a row is a "Previous Row". however, a self join should do what you want:
select *
from Table1 this
join Table2 prev on this.incrementalID = prev.incrementalID+1
If you have the following table
CREATE TABLE MyTable (
Id INT NOT NULL,
ChangeDate DATETIME NOT NULL,
.
.
.
)
The following query will return the previous record for any record from MyTable.
SELECT tbl.Id,
tbl.ChangeDate,
hist.Id,
hist.ChangeDate
FROM MyTable tbl
INNER JOIN MyTable hist
ON hist.Id = tbl.Id
AND hiost.ChangeDate = (SELECT MAX(ChangeDate)
FROM MyTable sub
WHERE sub.Id = tbl.Id AND sub.ChangeDate < tbl.ChangeDate)