问题
I am trying to sum INTERVAL. E.g.
SELECT SUM(TIMESTAMP1 - TIMESTAMP2) FROM DUAL
Is it possible to write a query that would work both on Oracle and SQL Server? If so, how?
Edit: changed DATE to INTERVAL
回答1:
I'm afraid you're going to be out of luck with a solution which works in both Oracle and MSSQL. Date arithmetic is something which is very different on the various flavours of DBMS.
Anyway, in Oracle we can use dates in straightforward arithmetic. And we have a function NUMTODSINTERVAL which turns a number into a DAY TO SECOND INTERVAL. So let's put them together.
Simple test data, two rows with pairs of dates rough twelve hours apart:
SQL> alter session set nls_date_format = 'dd-mon-yyyy hh24:mi:ss'
2 /
Session altered.
SQL> select * from t42
2 /
D1 D2
-------------------- --------------------
27-jul-2010 12:10:26 27-jul-2010 00:00:00
28-jul-2010 12:10:39 28-jul-2010 00:00:00
SQL>
Simple SQL query to find the sum of elapsed time:
SQL> select numtodsinterval(sum(d1-d2), 'DAY')
2 from t42
3 /
NUMTODSINTERVAL(SUM(D1-D2),'DAY')
-----------------------------------------------------
+000000001 00:21:04.999999999
SQL>
Just over a day, which is what we would expect.
"Edit: changed DATE to INTERVAL"
Working with TIMESTAMP columns is a little more labourious, but we can still work the same trick.
In the following sample. T42T is the same as T42 only the columns have TIMESTAMP rather than DATE for their datatype. The query extracts the various components of the DS INTERVAL and converts them into seconds, which are then summed and converted back into an INTERVAL:
SQL> select numtodsinterval(
2 sum(
3 extract (day from (t1-t2)) * 86400
4 + extract (hour from (t1-t2)) * 3600
5 + extract (minute from (t1-t2)) * 600
6 + extract (second from (t1-t2))
7 ), 'SECOND')
8 from t42t
9 /
NUMTODSINTERVAL(SUM(EXTRACT(DAYFROM(T1-T2))*86400+EXTRACT(HOURFROM(T1-T2))*
---------------------------------------------------------------------------
+000000001 03:21:05.000000000
SQL>
At least this result is in round seconds!
回答2:
Ok, after a bit of hell, with the help of the stackoverflowers' answers I've found the solution that fits my needs.
SELECT
SUM(CAST((DATE1 + 0) - (DATE2 + 0) AS FLOAT) AS SUM_TURNAROUND
FROM MY_BEAUTIFUL_TABLE
GROUP BY YOUR_CHOSEN_COLUMN
This returns a float (which is totally fine for me) that represents days both on Oracle ant SQL Server.
The reason I added zero to both DATEs is because in my case date columns on Oracle DB are of TIMESTAMP type and on SQL Server are of DATETIME type (which is obviously weird). So adding zero to TIMESTAMP on Oracle works just like casting to date and it does not have any effect on SQL Server DATETIME type.
Thank you guys! You were really helpful.
回答3:
You can't sum two datetimes. It wouldn't make sense - i.e. what does 15:00:00 plus 23:59:00 equal? Some time the next day? etc
But you can add a time increment by using a function like Dateadd() in SQL Server.
回答4:
In SQL Server as long as your individual timespans are all less than 24 hours you can do something like
WITH TIMES AS
(
SELECT CAST('01:01:00' AS DATETIME) AS TimeSpan
UNION ALL
SELECT '00:02:00'
UNION ALL
SELECT '23:02:00'
UNION ALL
SELECT '17:02:00'
--UNION ALL SELECT '24:02:00' /*This line would fail!*/
),
SummedTimes As
(
SELECT cast(SUM(CAST(TimeSpan AS FLOAT)) as datetime) AS [Summed] FROM TIMES
)
SELECT
FLOOR(CAST(Summed AS FLOAT)) AS D,
DATEPART(HOUR,[Summed]) AS H,
DATEPART(MINUTE,[Summed]) AS M,
DATEPART(SECOND,[Summed]) AS S
FROM SummedTimes
Gives
D H M S
----------- ----------- ----------- -----------
1 17 7 0
If you wanted to handle timespans greater than 24 hours I think you'd need to look at CLR integration and the TimeSpan structure. Definitely not portable!
Edit: SQL Server 2008 has a DateTimeOffset datatype that might help but that doesn't allow either SUMming or being cast to float
回答5:
I also do not think this is possible. Go with custom solutions that calculates the date value according to your preferences.
回答6:
You can also use this:
select
EXTRACT (DAY FROM call_end_Date - call_start_Date)*86400 +
EXTRACT (HOUR FROM call_end_Date - call_start_Date)*3600 +
EXTRACT (MINUTE FROM call_end_Date - call_start_Date)*60 +
extract (second FROM call_end_Date - call_start_Date) as interval
from table;
回答7:
You Can write you own aggregate function :-). Please read carefully http://docs.oracle.com/cd/B19306_01/appdev.102/b14289/dciaggfns.htm
You must create object type and its body by template, and next aggregate function what using this object:
create or replace type Sum_Interval_Obj as object
(
-- Object for creating and support custom aggregate function
duration interval day to second, -- In this property You sum all interval
-- Object Init
static function ODCIAggregateInitialize(
actx IN OUT Sum_Interval_Obj
) return number,
-- Iterate getting values from dataset
member function ODCIAggregateIterate(
self IN OUT Sum_Interval_Obj,
ad_interval IN interval day to second
) return number,
-- Merge parallel summed data
member function ODCIAggregateMerge(
self IN OUT Sum_Interval_Obj,
ctx2 IN Sum_Interval_Obj
) return number,
-- End of query, returning summary result
member function ODCIAggregateTerminate
(
self IN Sum_Interval_Obj,
returnValue OUT interval day to second,
flags IN number
) return number
)
/
create or replace type body Sum_Interval_Obj is
-- Object Init
static function ODCIAggregateInitialize(
actx IN OUT Sum_Interval_Obj
) return number
is
begin
actx := Sum_Interval_Obj(numtodsinterval(0,'SECOND'));
return ODCIConst.Success;
end ODCIAggregateInitialize;
-- Iterate getting values from dataset
member function ODCIAggregateIterate(
self IN OUT Sum_Interval_Obj,
ad_interval IN interval day to second
) return number
is
begin
self.duration := self.duration + ad_interval;
return ODCIConst.Success;
exception
when others then
return ODCIConst.Error;
end ODCIAggregateIterate;
-- Merge parallel calculated intervals
member function ODCIAggregateMerge(
self IN OUT Sum_Interval_Obj,
ctx2 IN Sum_Interval_Obj
) return number
is
begin
self.duration := self.duration + ctx2.duration; -- Add two intervals
-- return = All Ok!
return ODCIConst.Success;
exception
when others then
return ODCIConst.Error;
end ODCIAggregateMerge;
-- End of query, returning summary result
member function ODCIAggregateTerminate(
self IN Sum_Interval_Obj,
returnValue OUT interval day to second,
flags IN number
) return number
is
begin
-- return = All Ok, too!
returnValue := self.duration;
return ODCIConst.Success;
end ODCIAggregateTerminate;
end;
/
-- You own new aggregate function:
CREATE OR REPLACE FUNCTION Sum_Interval(
a_Interval interval day to second
) RETURN interval day to second
PARALLEL_ENABLE AGGREGATE USING Sum_Interval_Obj;
/
Last, check your function:
select sum_interval(duration)
from (select numtodsinterval(1,'SECOND') as duration from dual union all
select numtodsinterval(1,'MINUTE') as duration from dual union all
select numtodsinterval(1,'HOUR') as duration from dual union all
select numtodsinterval(1,'DAY') as duration from dual);
Finally You can create SUM function, if you want.
来源：https://stackoverflow.com/questions/3352057/sql-is-it-possible-to-sum-fields-of-interval-type