Related
I have a postgres table with a unique datetime field.
I would like to use/create a function that takes as argument a datetime value and returns the row id having the closest datetime relative (but not equal) to the passed datetime value. A second argument could specify before or after the passed value.
Ideally, some combination of native datetime functions could handle this requirement. Otherwise it'll have to be a custom function.
Question: What are methods for querying relative datetime over a collection of rows?
select id, passed_ts - ts_column difference
from t
where
passed_ts > ts_column and positive_interval
or
passed_ts < ts_column and not positive_interval
order by abs(extract(epoch from passed_ts - ts_column))
limit 1
passed_ts is the timestamp parameter and positive_interval is a boolean parameter. If true only rows where the timestamp column is lower then the passed timestamp. If false the inverse.
use simply -.
Assuming you have a table with attributes Key, Attr and T (timestamp with or without timezone):
you can search with
select min(T - TimeValue) from Table where (T - TimeValue) > 0;
this will give you the main difference. You can combine this value with a join to the same table to get the tuple you are interested in:
select * from (select *, T - TimeValue as diff from Table) as T1 NATURAL JOIN
( select min(T - TimeValue) as diff from Table where (T - TimeValue) > 0) as T2;
that should do it
--dmg
You want the first row of a select statement producing all the rows below (or above) the given datetime in descending (or ascending) order.
Pseudo code for the function body:
SELECT id
FROM table
WHERE IF(#above, datecol < #param, datecol > #param)
ORDER BY IF (#above. datecol ASC, datecol DESC)
LIMIT 1
However, this does not work: one cannot condition the ordering direction.
The second idea is to do both queries, and select afterwards:
SELECT *
FROM (
(
SELECT 'below' AS dir, id
FROM table
WHERE datecol < #param
ORDER BY datecol DESC
LIMIT 1
) UNION (
SELECT 'above' AS dir, id
FROM table
WHERE datecol > #param
ORDER BY datecol ASC
LIMIT 1)
) AS t
WHERE dir = #dir
That should be pretty fast with an index on the datetime column.
-- test rig
DROP SCHEMA tmp CASCADE;
CREATE SCHEMA tmp ;
SET search_path=tmp;
CREATE TABLE lutser
( dt timestamp NOT NULL PRIMARY KEY
);
-- populate it
INSERT INTO lutser(dt)
SELECT gs
FROM generate_series('2013-04-30', '2013-05-01', '1 min'::interval) gs
;
DELETE FROM lutser WHERE random() < 0.9;
--
-- The query:
WITH xyz AS (
SELECT dt AS hh
, LAG (dt) OVER (ORDER by dt ) AS ll
FROM lutser
)
SELECT *
FROM xyz bb
WHERE '2013-04-30 12:00' BETWEEN bb.ll AND bb.hh
;
Result:
NOTICE: drop cascades to table tmp.lutser
DROP SCHEMA
CREATE SCHEMA
SET
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "lutser_pkey" for table "lutser"
CREATE TABLE
INSERT 0 1441
DELETE 1288
hh | ll
---------------------+---------------------
2013-04-30 12:02:00 | 2013-04-30 11:50:00
(1 row)
Wrapping it into a function is left as an excercise for the reader
UPDATE: here is a second one with the sandwiched-not-exists-trick (TM):
SELECT lo.dt AS ll
FROM lutser lo
JOIN lutser hi ON hi.dt > lo.dt
AND NOT EXISTS (
SELECT * FROM lutser nx
WHERE nx.dt < hi.dt
AND nx.dt > lo.dt
)
WHERE '2013-04-30 12:00' BETWEEN lo.dt AND hi.dt
;
You have to join the table to itself with the where condition looking for the smallest nonzero (negative or positive) interval between the base table row's datetime and the joined table row's datetime. It would be good to have an index on that datetime column.
P.S. You could also look for the max() of the previous or the min() of the subsequent.
Try something like:
SELECT *
FROM your_table
WHERE (dt_time > argument_time and search_above = 'true')
OR (dt_time < argument_time and search_above = 'false')
ORDER BY CASE WHEN search_above = 'true'
THEN dt_time - argument_time
ELSE argument_time - dt_time
END
LIMIT 1;
I am wondering if there is some easy way, a function, or other method to return data from a query with the following results.
I have a SQL Express DB 2008 R2, a table that contains numerical data in a given column, say col T.
I am given a value X in code and would like to return up to three records. The record where col T equals my value X, and the record before and after, and nothing else. The sort is done on col T. The record before may be beginning of file and therefore not exist, likewise, if X equals the last record then the record after would be non existent, end of file/table.
The value of X may not exist in the table.
This I think is similar to get a range of results in numerical order.
Any help or direction in solving this would be greatly appreciated.
Thanks again,
It might not be the most optimal solution, but:
SELECT T
FROM theTable
WHERE T = X
UNION ALL
SELECT *
FROM
(
SELECT TOP 1 T
FROM theTable
WHERE T > X
ORDER BY T
) blah
UNION ALL
SELECT *
FROM
(
SELECT TOP 1 T
FROM theTable
WHERE T < X
ORDER BY T DESC
) blah2
DECLARE #x int = 100
;WITH t as
(
select ROW_NUMBER() OVER (ORDER BY T ASC) AS row_nm,*
from YourTable
)
, t1 as
(
select *
from t
WHERE T = #x
)
select *
from t
CROSS APPLY t1
WHERE t.row_nm BETWEEN t1.row_nm -1 and t1.row_nm + 1
Assume we have a table and we want to do a sum of the Expend column so that the summation only adds up values of the same Week_Name.
SN Week_Name Exp Sum
-- --------- --- ---
1 Week 1 10 0
2 Week 1 20 0
3 Week 1 30 60
4 Week 2 40 0
5 Week 2 50 90
6 Week 3 10 0
I will assume we will need to `Order By' Week_Name, then compare the previous Week_Name(previous row) with the current row Week_name(Current row).
If both are the same, put zero in the SUM column.
If not the same, add all expenditure, where Week_Name = Week_Name(Previous row) and place in the Sum column. The final output should look like the table above.
Any help on how to achieve this in T-SQL is highly appreciated.
Okay, I was eventually able to resolve this issue, praise Jesus! If you want the exact table I gave above, you can use GilM's response below, it is perfect. If you want your table to have running Cumulatives, i.e. Rows 3 shoud have 60, Row 5, should have 150, Row 6 160 etc. Then, you can use my code below:
USE CAPdb
IF OBJECT_ID ('dbo.[tablebp]') IS NOT NULL
DROP TABLE [tablebp]
GO
CREATE TABLE [tablebp] (
tablebpcCol1 int PRIMARY KEY
,tabledatekey datetime
,tableweekname varchar(50)
,expenditure1 numeric
,expenditure_Cummulative numeric
)
INSERT INTO [tablebp](tablebpcCol1,tabledatekey,tableweekname,expenditure1,expenditure_Cummulative)
SELECT b.s_tablekey,d.PK_Date,d.Week_Name,
SUM(b.s_expenditure1) AS s_expenditure1,
SUM(b.s_expenditure1) + COALESCE((SELECT SUM(s_expenditure1)
FROM source_table bs JOIN dbo.Time dd ON bs.[DATE Key] = dd.[PK_Date]
WHERE dd.PK_Date < d.PK_Date),0)
FROM source_table b
INNER JOIN dbo.Time d ON b.[Date key] = d.PK_Date
GROUP BY d.[PK_Date],d.Week_Name,b.s_tablekey,b.s_expenditure1
ORDER BY d.[PK_Date]
;WITH CTE AS (
SELECT tableweekname
,Max(expenditure_Cummulative) AS Week_expenditure_Cummulative
,MAX(tablebpcCol1) AS MaxSN
FROM [tablebp]
GROUP BY tableweekname
)
SELECT [tablebp].*
,CASE WHEN [tablebp].tablebpcCol1 = CTE.MaxSN THEN Week_expenditure_Cummulative
ELSE 0 END AS [RunWeeklySum]
FROM [tablebp]
JOIN CTE on CTE.tableweekname = [tablebp].tableweekname
I'm not sure why your SN=6 line is 0 rather than 10. Do you really not want the sum for the last Week? If having the last week total is okay, then you might want something like:
;WITH CTE AS (
SELECT Week_Name,SUM([Expend.]) as SumExpend
,MAX(SN) AS MaxSN
FROM T
GROUP BY Week_Name
)
SELECT T.*,CASE WHEN T.SN = CTE.MaxSN THEN SumExpend
ELSE 0 END AS [Sum]
FROM T
JOIN CTE on CTE.Week_Name = T.Week_Name
Based on the requst in the comment wanting a running total in SUM you could try this:
;WITH CTE AS (
SELECT Week_Name, MAX(SN) AS MaxSN
FROM T
GROUP BY Week_Name
)
SELECT T.SN, T.Week_Name,T.Exp,
CASE WHEN T.SN = CTE.MaxSN THEN
(SELECT SUM(EXP) FROM T T2
WHERE T2.SN <= T.SN) ELSE 0 END AS [SUM]
FROM T
JOIN CTE ON CTE.Week_Name = T.Week_Name
ORDER BY SN
I need to select rows where a column (that is varchar) contains 10 or more digits (any) in a row.
'115555711111' - true
'abc11143555111111def' - true
'000345345500abc' - true
'1411a6551a111' - false
This does not work:
SELECT * FROM Table WHERE PATINDEX('%[0-9]{10}%', Column1) > 0
SELECT *
FROM Table
WHERE Column1 LIKE '%' + REPLICATE('[0-9]',10) + '%'
I have two variables, one is called PaidThisMonth, and the other is called OwedPast. They are both results of some subqueries in SQL. How can I select the smaller of the two and return it as a value titled PaidForPast?
The MIN function works on columns, not variables.
SQL Server 2012 and 2014 supports IIF(cont,true,false) function. Thus for minimal selection you can use it like
SELECT IIF(first>second, second, first) the_minimal FROM table
While IIF is just a shorthand for writing CASE...WHEN...ELSE, it's easier to write.
The solutions using CASE, IIF, and UDF are adequate, but impractical when extending the problem to the general case using more than 2 comparison values. The generalized
solution in SQL Server 2008+ utilizes a strange application of the VALUES clause:
SELECT
PaidForPast=(SELECT MIN(x) FROM (VALUES (PaidThisMonth),(OwedPast)) AS value(x))
Credit due to this website:
http://sqlblog.com/blogs/jamie_thomson/archive/2012/01/20/use-values-clause-to-get-the-maximum-value-from-some-columns-sql-server-t-sql.aspx
Use Case:
Select Case When #PaidThisMonth < #OwedPast
Then #PaidThisMonth Else #OwedPast End PaidForPast
As Inline table valued UDF
CREATE FUNCTION Minimum
(#Param1 Integer, #Param2 Integer)
Returns Table As
Return(Select Case When #Param1 < #Param2
Then #Param1 Else #Param2 End MinValue)
Usage:
Select MinValue as PaidforPast
From dbo.Minimum(#PaidThisMonth, #OwedPast)
ADDENDUM:
This is probably best for when addressing only two possible values, if there are more than two, consider Craig's answer using Values clause.
For SQL Server 2022+ (or MySQL or PostgreSQL 9.3+), a better way is to use the LEAST and GREATEST functions.
SELECT GREATEST(A.date0, B.date0) AS date0,
LEAST(A.date1, B.date1, B.date2) AS date1
FROM A, B
WHERE B.x = A.x
With:
GREATEST(value [, ...]) : Returns the largest (maximum-valued) argument from values provided
LEAST(value [, ...]) Returns the smallest (minimum-valued) argument from values provided
Documentation links :
MySQL http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html
Postgres https://www.postgresql.org/docs/current/functions-conditional.html
SQL Server https://learn.microsoft.com/en-us/sql/t-sql/functions/logical-functions-least-transact-sql
I just had a situation where I had to find the max of 4 complex selects within an update.
With this approach you can have as many as you like!
You can also replace the numbers with aditional selects
select max(x)
from (
select 1 as 'x' union
select 4 as 'x' union
select 3 as 'x' union
select 2 as 'x'
) a
More complex usage
#answer = select Max(x)
from (
select #NumberA as 'x' union
select #NumberB as 'x' union
select #NumberC as 'x' union
select (
Select Max(score) from TopScores
) as 'x'
) a
I'm sure a UDF has better performance.
Here is a trick if you want to calculate maximum(field, 0):
SELECT (ABS(field) + field)/2 FROM Table
returns 0 if field is negative, else, return field.
Use a CASE statement.
Example B in this page should be close to what you're trying to do:
http://msdn.microsoft.com/en-us/library/ms181765.aspx
Here's the code from the page:
USE AdventureWorks;
GO
SELECT ProductNumber, Name, 'Price Range' =
CASE
WHEN ListPrice = 0 THEN 'Mfg item - not for resale'
WHEN ListPrice < 50 THEN 'Under $50'
WHEN ListPrice >= 50 and ListPrice < 250 THEN 'Under $250'
WHEN ListPrice >= 250 and ListPrice < 1000 THEN 'Under $1000'
ELSE 'Over $1000'
END
FROM Production.Product
ORDER BY ProductNumber ;
GO
This works for up to 5 dates and handles nulls. Just couldn't get it to work as an Inline function.
CREATE FUNCTION dbo.MinDate(#Date1 datetime = Null,
#Date2 datetime = Null,
#Date3 datetime = Null,
#Date4 datetime = Null,
#Date5 datetime = Null)
RETURNS Datetime AS
BEGIN
--USAGE select dbo.MinDate('20120405',null,null,'20110305',null)
DECLARE #Output datetime;
WITH Datelist_CTE(DT)
AS (
SELECT #Date1 AS DT WHERE #Date1 is not NULL UNION
SELECT #Date2 AS DT WHERE #Date2 is not NULL UNION
SELECT #Date3 AS DT WHERE #Date3 is not NULL UNION
SELECT #Date4 AS DT WHERE #Date4 is not NULL UNION
SELECT #Date5 AS DT WHERE #Date5 is not NULL
)
Select #Output=Min(DT) FROM Datelist_CTE;
RETURN #Output;
END;
Building on the brilliant logic / code from mathematix and scottyc, I submit:
DECLARE #a INT, #b INT, #c INT = 0;
WHILE #c < 100
BEGIN
SET #c += 1;
SET #a = ROUND(RAND()*100,0)-50;
SET #b = ROUND(RAND()*100,0)-50;
SELECT #a AS a, #b AS b,
#a - ( ABS(#a-#b) + (#a-#b) ) / 2 AS MINab,
#a + ( ABS(#b-#a) + (#b-#a) ) / 2 AS MAXab,
CASE WHEN (#a <= #b AND #a = #a - ( ABS(#a-#b) + (#a-#b) ) / 2)
OR (#a >= #b AND #a = #a + ( ABS(#b-#a) + (#b-#a) ) / 2)
THEN 'Success' ELSE 'Failure' END AS Status;
END;
Although the jump from scottyc's MIN function to the MAX function should have been obvious to me, it wasn't, so I've solved for it and included it here: SELECT #a + ( ABS(#b-#a) + (#b-#a) ) / 2. The randomly generated numbers, while not proof, should at least convince skeptics that both formulae are correct.
Use a temp table to insert the range of values, then select the min/max of the temp table from within a stored procedure or UDF. This is a basic construct, so feel free to revise as needed.
For example:
CREATE PROCEDURE GetMinSpeed() AS
BEGIN
CREATE TABLE #speed (Driver NVARCHAR(10), SPEED INT);
'
' Insert any number of data you need to sort and pull from
'
INSERT INTO #speed (N'Petty', 165)
INSERT INTO #speed (N'Earnhardt', 172)
INSERT INTO #speed (N'Patrick', 174)
SELECT MIN(SPEED) FROM #speed
DROP TABLE #speed
END
Select MIN(T.V) FROM (Select 1 as V UNION Select 2 as V) T
SELECT (WHEN first > second THEN second ELSE first END) the_minimal FROM table