Calculate a Running Total in SQL Server

Question

Imagine the following table  called TestTable    id     somedate    somevalue --     --------    --------- 45     01 Jan 09   3 23     08 Jan 09   5 12     02 Feb 09   0 77     14 Feb 09   7 39     20 Feb 09   34 33     02 Mar 09   6   I would like a query that returns a running total in date order  like   id     somedate    somevalue  runningtotal --     --------    ---------  ------------ 45     01 Jan 09   3          3 23     08 Jan 09   5          8 12     02 Feb 09   0          8 77     14 Feb 09   7          15   39     20 Feb 09   34         49 33     02 Mar 09   6          55   I know there are various ways of doing this in SQL Server 2000   2005   2008   I am particularly interested in this sort of method that uses the aggregating-set-statement trick   INSERT INTO  AnotherTbl id  somedate  somevalue  runningtotal      SELECT id  somedate  somevalue  null    FROM TestTable    ORDER BY somedate  DECLARE  RunningTotal int SET  RunningTotal   0  UPDATE  AnotherTbl SET  RunningTotal   runningtotal    RunningTotal   somevalue FROM  AnotherTbl       this is very efficient but I have heard there are issues around this because you can t necessarily guarantee that the UPDATE statement will process the rows in the correct order  Maybe we can get some definitive answers about that issue   But maybe there are other ways that people can suggest   edit  Now with a SqlFiddle with the setup and the  update trick  example above

User · Answer

You can also denormalize - store running totals in the same table:

http://sqlblog.com/blogs/alexander_kuznetsov/archive/2009/01/23/denormalizing-to-enforce-business-rules-running-totals.aspx

Selects work much faster than any other solutions, but modifications may be slower

User · Answer

I believe a running total can be achieved using the simple INNER JOIN operation below   SELECT      ROW NUMBER   OVER  ORDER BY SomeDate  AS OrderID      rt   INTO      tmp FROM               SELECT 45 AS ID  CAST  01-01-2009  AS DATETIME  AS SomeDate  3 AS SomeValue         UNION ALL         SELECT 23  CAST  01-08-2009  AS DATETIME   5         UNION ALL         SELECT 12  CAST  02-02-2009  AS DATETIME   0         UNION ALL         SELECT 77  CAST  02-14-2009  AS DATETIME   7         UNION ALL         SELECT 39  CAST  02-20-2009  AS DATETIME   34         UNION ALL         SELECT 33  CAST  03-02-2009  AS DATETIME   6       rt  SELECT      t1 ID      t1 SomeDate      t1 SomeValue      SUM t2 SomeValue  AS RunningTotal FROM      tmp t1     JOIN  tmp t2         ON t2 OrderID  lt   t1 OrderID GROUP BY      t1 OrderID      t1 ID      t1 SomeDate      t1 SomeValue ORDER BY     t1 OrderID  DROP TABLE  tmp

User · Answer

Here are 2 simple ways to calculate running total   Approach 1  It can be written this way if your DBMS supports Analytical Functions  SELECT     id             somedate             somevalue             runningtotal   SUM somevalue  OVER  ORDER BY somedate ASC  FROM       TestTable   Approach 2  You can make use of OUTER APPLY if your database version   DBMS itself does not support Analytical Functions  SELECT     T id             T somedate             T somevalue             runningtotal   OA runningtotal FROM       TestTable T            OUTER APPLY                              SELECT   runningtotal   SUM TI somevalue                             FROM     TestTable TI                            WHERE    TI somedate  lt   S somedate                          OA    Note - If you have to calculate the running total for different partitions separately  it can be done as posted here  Calculating Running totals across rows and grouping by ID

User · Answer

While Sam Saffron did great work on it  he still didn t provide recursive common table expression code for this problem  And for us who working with SQL Server 2008 R2 and not Denali  it s still fastest way to get running total  it s about 10 times faster than cursor on my work computer for 100000 rows  and it s also inline query  So  here it is  I m supposing that there s an ord column in the table and it s sequential number without gaps  for fast processing there also should be unique constraint on this number     with  CTE RunningTotal as       select T ord  T total  T total as running total     from  t as T     where T ord   0     union all     select T ord  T total  T total   C running total as running total     from CTE RunningTotal as C         inner join  t as T on T ord   C ord   1   select C ord  C total  C running total from CTE RunningTotal as C option  maxrecursion 0   -- CPU 140  Reads 110014  Duration 132   sql fiddle demo  update I also was curious about this update with variable or quirky update  So usually it works ok  but how we can be sure that it works every time  well  here s a little trick  found it here - http   www sqlservercentral com Forums Topic802558-203-21 aspx bm981258  - you just check current and previous ord and use 1 0 assignment in case they are different from what you expecting   declare  total int   ord int  select  total   0   ord   -1  update  t set      total    total   total       ord   case when ord  lt  gt   ord   1 then 1 0 else ord end      ------------------------     running total    total  select   from  t  -- CPU 0  Reads 58  Duration 139   From what I ve seen if you have proper clustered index primary key on your table  in our case it would be index by ord id  update will proceed in a linear way all the time  never encountered divide by zero   That said  it s up to you to decide if you want to use it in production code     update 2 I m linking this answer  cause it includes some useful info about unreliability of the quirky update - nvarchar concatenation   index   nvarchar max  inexplicable behavior

User · Answer

Though best way is to get it done will be using a window function  it can also be done using a simple correlated sub-query   Select id  someday  somevalue   select sum somevalue                                   from testtable as t2                                 where t2 id   t1 id                                 and t2 someday  lt   t1 someday  as runningtotal from testtable as t1 order by id someday

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The following will produce the required results   SELECT a SomeDate         a SomeValue         SUM b SomeValue  AS RunningTotal FROM TestTable a CROSS JOIN TestTable b WHERE  b SomeDate  lt   a SomeDate   GROUP BY a SomeDate a SomeValue ORDER BY a SomeDate a SomeValue   Having a clustered index on SomeDate will greatly improve the performance

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Using join Another variation is to use join  Now the query could look like       SELECT a id  a value  SUM b Value FROM   RunTotalTestData a      RunTotalTestData b     WHERE b id  lt   a id     GROUP BY a id  a value      ORDER BY a id    for more you can visite this link http   askme indianyouth info details calculating-simple-running-totals-in-sql-server-12

User · Answer

In SQL Server 2012 you can use SUM   with the OVER   clause   select id         somedate         somevalue         sum somevalue  over order by somedate rows unbounded preceding  as runningtotal from TestTable   SQL Fiddle

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Update  if you are running SQL Server 2012 see  https   stackoverflow com a 10309947  The problem is that the SQL Server implementation of the Over clause is somewhat limited    Oracle  and ANSI-SQL  allow you to do things like     SELECT somedate  somevalue    SUM somevalue  OVER ORDER BY somedate       ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW             AS RunningTotal   FROM Table   SQL Server gives you no clean solution to this problem  My gut is telling me that this is one of those rare cases where a cursor is the fastest  though I will have to do some benchmarking on big results   The update trick is handy but I feel its fairly fragile  It seems that if you are updating a full table then it will proceed in the order of the primary key  So if you set your date as a primary key ascending you will probably be safe  But you are relying on an undocumented SQL Server implementation detail  also if the query ends up being performed by two procs I wonder what will happen  see  MAXDOP     Full working sample    drop table  t  create table  t   ord int primary key  total int  running total int   insert  t ord total   values  2 20  -- notice the malicious re-ordering  insert  t ord total  values  1 10  insert  t ord total   values  3 10  insert  t ord total   values  4 1   declare  total int  set  total   0 update  t set running total    total   total    total   total   select   from  t order by ord   ord         total       running total ----------- ----------- ------------- 1           10          10 2           20          30 3           10          40 4           1           41   You asked for a benchmark this is the lowdown    The fastest SAFE way of doing this would be the Cursor  it is an order of magnitude faster than the correlated sub-query of cross-join    The absolute fastest way is the UPDATE trick  My only concern with it is that I am not certain that under all circumstances the update will proceed in a linear way  There is nothing in the query that explicitly says so    Bottom line  for production code I would go with the cursor    Test data    create table  t   ord int primary key  total int  running total int   set nocount on  declare  i int set  i   0  begin tran while  i  lt  10000 begin    insert  t  ord  total  values   i   rand     100       set  i    i  1 end commit   Test 1   SELECT ord total        SELECT SUM total           FROM  t b          WHERE b ord  lt   a ord  AS b  FROM  t a  -- CPU 11731  Reads 154934  Duration 11135    Test 2    SELECT a ord  a total  SUM b total  AS RunningTotal  FROM  t a CROSS JOIN  t b  WHERE  b ord  lt   a ord   GROUP BY a ord a total  ORDER BY a ord  -- CPU 16053  Reads 154935  Duration 4647   Test 3   DECLARE  TotalTable table ord int primary key  total int  running total int   DECLARE forward cursor CURSOR FAST FORWARD  FOR  SELECT ord  total FROM  t  ORDER BY ord   OPEN forward cursor   DECLARE  running total int        ord int        total int SET  running total   0  FETCH NEXT FROM forward cursor INTO  ord   total  WHILE    FETCH STATUS   0  BEGIN      SET  running total    running total    total      INSERT  TotalTable VALUES  ord   total   running total       FETCH NEXT FROM forward cursor INTO  ord   total  END  CLOSE forward cursor DEALLOCATE forward cursor  SELECT   FROM  TotalTable  -- CPU 359  Reads 30392  Duration 496   Test 4    declare  total int  set  total   0 update  t set running total    total   total    total   total   select   from  t  -- CPU 0  Reads 58  Duration 139

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If you are using Sql server 2008 R2 above  Then  It would be shortest way to do   Select id      somedate      somevalue  LAG runningtotal  OVER  ORDER BY somedate    somevalue AS runningtotal From TestTable    LAG is use to get previous row value  You can do google for more info    1

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The APPLY operator in SQL 2005 and higher works for this   select     t id       t somedate       t somevalue       rt runningTotal from TestTable t  cross apply  select sum somevalue  as runningTotal                 from TestTable                 where somedate  lt   t somedate               as rt order by t somedate

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Use a correlated sub-query  Very simple  here you go   SELECT  somedate    SELECT SUM somevalue  FROM TestTable t2 WHERE t2 somedate lt  t1 somedate  AS running total FROM TestTable t1 GROUP BY somedate ORDER BY somedate   The code might not be exactly correct  but I m sure that the idea is   The GROUP BY is in case a date appears more than once  you would only want to see it once in the result set   If you don t mind seeing repeating dates  or you want to see the original value and id  then the following is what you want   SELECT  id  somedate   somevalue   SELECT SUM somevalue  FROM TestTable t2 WHERE t2 somedate lt  t1 somedate  AS running total FROM TestTable t1 ORDER BY somedate

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SELECT TOP 25   amount        SELECT SUM amount       FROM time detail b      WHERE b time detail id  lt   a time detail id  AS Total FROM time detail a   You can also use the ROW NUMBER   function and a temp table to create an arbitrary column to use in the comparison on the inner SELECT statement

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Assuming that windowing works on SQL Server 2008  like it does elsewhere  that I ve tried   give this a go   select testtable    sum somevalue  over order by somedate  from testtable order by somedate    MSDN says it s available in SQL Server 2008  and maybe 2005 as well   but I don t have an instance to hand to try it   EDIT  well  apparently SQL Server doesn t allow a window specification   OVER        without specifying  PARTITION BY   dividing the result up into groups but not aggregating in quite the way GROUP BY does   Annoying-- the MSDN syntax reference suggests that its optional  but I only have SqlServer 2000 instances around at the moment   The query I gave works in both Oracle 10 2 0 3 0 and PostgreSQL 8 4-beta  So tell MS to catch up

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BEGIN TRAN CREATE TABLE  Table   Id INT IDENTITY 1 1   id INT      somedate VARCHAR 100    somevalue INT    INSERT INTO  Table   id       somedate    somevalue    SELECT 45    01 Jan 09   3 UNION ALL SELECT 23    08 Jan 09   5 UNION ALL SELECT 12    02 Feb 09   0 UNION ALL SELECT 77    14 Feb 09   7 UNION ALL SELECT 39    20 Feb 09   34 UNION ALL SELECT 33    02 Mar 09   6    WITH CTE    Id  id      somedate     somevalue   totvalue   AS     SELECT  Id   id       somedate    somevalue  somevalue  FROM  Table WHERE  id   1  UNION ALL  SELECT  Table  Id    Table id    somedate    somevalue   somevalue    totvalue  FROM  Table CTE   WHERE  Table  id  gt  1 AND CTE  Id      Table  id-1      SELECT   FROM CTE  ROLLBACK TRAN

[sql] Calculate a Running Total in SQL Server

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