RunningAVG
Updated: 31 Oct 2012
Use RunningAVG to calculate the average of column values in an ordered resultant table, without having to do a self-join. The average value is calculated for each value from the first value to the last value in the ordered group or partition. If the column values are presented to the functions out of order, an error message will be generated.
Syntax
SELECT [wctWindowing].[wct].[RunningAVG] (
<@Val, float,>
,<@RowNum, int,>
,<@Id, tinyint,>)
Arguments
@Val
the value passed into the function. @Val is an expression of type float or of a type that can be implicitly converted to float.
@RowNum
the number of the row within the group for which the average is being calculated. If @RowNum for the current row in a set is less than or equal to the previous @RowNum and @RowNum is not equal to 1, an error message will be generated. @RowNum is an expression of type int or of a type that can be implicitly converted to int.
@Id
a unique identifier for the RunningAVG calculation. @Id allows you to specify multiple RunningAVG calculations within a resultant table. @Id is an expression of type tinyint or of a type that can be implicitly converted to tinyint.
Remarks
· If @Id is NULL then @Id = 0.
· To calculate moving averages, use the MovingAVG function.
· To calculate moving averages for time series, use the DEMA or DWMA function.
· If @RowNum is equal to 1, RunningAVG is equal to @Val.
· @RowNum must be in ascending order.
· There may be cases where the order in which the data are returned to the function and the order in which the results are returned are different, generally due to parallelism. You can use OPTION(MAXDOP 1) or OPTION(MAXDOP 1,FORCE ORDER) to help eliminate this problem.
Example
In this example we will calculate the average check amount in a check register from the first check to the last check. We will create a temporary table, #c, populate it with some data and then run the SELECT.
/*Create the temporary table*/
CREATE TABLE #c (
num_check int,
date_check datetime,
payee varchar(50),
amt_check money,
Primary Key (num_check)
)
/*Populate the table with some data*/
INSERT INTO #c VALUES (1200,'2012-01-31','Gas Company',108.49)
INSERT INTO #c VALUES (1201,'2012-01-31','Electric Company',98.27)
INSERT INTO #c VALUES (1202,'2012-01-31','Telephone Company',136.6)
INSERT INTO #c VALUES (1203,'2012-01-31','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1204,'2012-01-31','Mortgage Bank',1129.23)
INSERT INTO #c VALUES (1205,'2012-02-29','Gas Company',153.89)
INSERT INTO #c VALUES (1206,'2012-02-29','Electric Company',121.99)
INSERT INTO #c VALUES (1207,'2012-02-29','Telephone Company',138.92)
INSERT INTO #c VALUES (1208,'2012-02-29','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1209,'2012-02-29','Mortgage Bank',1129.23)
INSERT INTO #c VALUES (1210,'2012-03-31','Gas Company',70.79)
INSERT INTO #c VALUES (1211,'2012-03-31','Electric Company',93.57)
INSERT INTO #c VALUES (1212,'2012-03-31','Telephone Company',149.78)
INSERT INTO #c VALUES (1213,'2012-03-31','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1214,'2012-03-31','Mortgage Bank',1129.23)
INSERT INTO #c VALUES (1215,'2012-04-30','Gas Company',105.58)
INSERT INTO #c VALUES (1216,'2012-04-30','Electric Company',149.36)
INSERT INTO #c VALUES (1217,'2012-04-30','Telephone Company',145.35)
INSERT INTO #c VALUES (1218,'2012-04-30','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1219,'2012-04-30','Mortgage Bank',1129.23)
INSERT INTO #c VALUES (1220,'2012-05-31','Gas Company',96.27)
INSERT INTO #c VALUES (1221,'2012-05-31','Electric Company',114.62)
INSERT INTO #c VALUES (1222,'2012-05-31','Telephone Company',145.43)
INSERT INTO #c VALUES (1223,'2012-05-31','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1224,'2012-05-31','Mortgage Bank',1129.23)
INSERT INTO #c VALUES (1225,'2012-06-30','Gas Company',147.03)
INSERT INTO #c VALUES (1226,'2012-06-30','Electric Company',130.52)
INSERT INTO #c VALUES (1227,'2012-06-30','Telephone Company',147.71)
INSERT INTO #c VALUES (1228,'2012-06-30','Car Leasing Company',361.75)
INSERT INTO #c VALUES (1229,'2012-06-30','Mortgage Bank',1129.23)
/*Calculate the running average*/
SELECT num_check
,cast(convert(varchar, date_check, 106) as char(11)) as date_check
,cast(payee as char(20)) as payee
,amt_check
,wct.RunningAvg(amt_check,num_check,NULL) as [Running AVG]
FROM #c
This produces the following result.
num_check date_check payee amt_check Running AVG
----------- ----------- -------------------- --------------------- ----------------------
1200 31 Jan 2012 Gas Company 108.49 108.49
1201 31 Jan 2012 Electric Company 98.27 103.38
1202 31 Jan 2012 Telephone Company 136.60 114.453333333333
1203 31 Jan 2012 Car Leasing Company 361.75 176.2775
1204 31 Jan 2012 Mortgage Bank 1129.23 366.868
1205 29 Feb 2012 Gas Company 153.89 331.371666666667
1206 29 Feb 2012 Electric Company 121.99 301.46
1207 29 Feb 2012 Telephone Company 138.92 281.1425
1208 29 Feb 2012 Car Leasing Company 361.75 290.098888888889
1209 29 Feb 2012 Mortgage Bank 1129.23 374.012
1210 31 Mar 2012 Gas Company 70.79 346.446363636364
1211 31 Mar 2012 Electric Company 93.57 325.373333333333
1212 31 Mar 2012 Telephone Company 149.78 311.866153846154
1213 31 Mar 2012 Car Leasing Company 361.75 315.429285714286
1214 31 Mar 2012 Mortgage Bank 1129.23 369.682666666667
1215 30 Apr 2012 Gas Company 105.58 353.17625
1216 30 Apr 2012 Electric Company 149.36 341.187058823529
1217 30 Apr 2012 Telephone Company 145.35 330.307222222222
1218 30 Apr 2012 Car Leasing Company 361.75 331.962105263158
1219 30 Apr 2012 Mortgage Bank 1129.23 371.8255
1220 31 May 2012 Gas Company 96.27 358.70380952381
1221 31 May 2012 Electric Company 114.62 347.609090909091
1222 31 May 2012 Telephone Company 145.43 338.818695652174
1223 31 May 2012 Car Leasing Company 361.75 339.774166666667
1224 31 May 2012 Mortgage Bank 1129.23 371.3524
1225 30 Jun 2012 Gas Company 147.03 362.724615384615
1226 30 Jun 2012 Electric Company 130.52 354.124444444445
1227 30 Jun 2012 Telephone Company 147.71 346.7525
1228 30 Jun 2012 Car Leasing Company 361.75 347.269655172414
1229 30 Jun 2012 Mortgage Bank 1129.23 373.335
In this example, we calculate the average by payee in date order and use the ROW_NUMBER() function to determine the @RowNum value passed into the RunningAVG function.
SELECT num_check
,cast(convert(varchar, date_check, 106) as char(11)) as date_check
,cast(payee as char(20)) as payee
,amt_check
,wct.RunningAvg(amt_check, ROW_NUMBER() OVER (PARTITION BY payee ORDER BY payee, num_check),NULL) as [Running AVG]
FROM #c
ORDER BY payee, num_check
This produces the following result.
num_check date_check payee amt_check Running AVG
----------- ----------- -------------------- --------------------- ----------------------
1203 31 Jan 2012 Car Leasing Company 361.75 361.75
1208 29 Feb 2012 Car Leasing Company 361.75 361.75
1213 31 Mar 2012 Car Leasing Company 361.75 361.75
1218 30 Apr 2012 Car Leasing Company 361.75 361.75
1223 31 May 2012 Car Leasing Company 361.75 361.75
1228 30 Jun 2012 Car Leasing Company 361.75 361.75
1201 31 Jan 2012 Electric Company 98.27 98.27
1206 29 Feb 2012 Electric Company 121.99 110.13
1211 31 Mar 2012 Electric Company 93.57 104.61
1216 30 Apr 2012 Electric Company 149.36 115.7975
1221 31 May 2012 Electric Company 114.62 115.562
1226 30 Jun 2012 Electric Company 130.52 118.055
1200 31 Jan 2012 Gas Company 108.49 108.49
1205 29 Feb 2012 Gas Company 153.89 131.19
1210 31 Mar 2012 Gas Company 70.79 111.056666666667
1215 30 Apr 2012 Gas Company 105.58 109.6875
1220 31 May 2012 Gas Company 96.27 107.004
1225 30 Jun 2012 Gas Company 147.03 113.675
1204 31 Jan 2012 Mortgage Bank 1129.23 1129.23
1209 29 Feb 2012 Mortgage Bank 1129.23 1129.23
1214 31 Mar 2012 Mortgage Bank 1129.23 1129.23
1219 30 Apr 2012 Mortgage Bank 1129.23 1129.23
1224 31 May 2012 Mortgage Bank 1129.23 1129.23
1229 30 Jun 2012 Mortgage Bank 1129.23 1129.23
1202 31 Jan 2012 Telephone Company 136.60 136.6
1207 29 Feb 2012 Telephone Company 138.92 137.76
1212 31 Mar 2012 Telephone Company 149.78 141.766666666667
1217 30 Apr 2012 Telephone Company 145.35 142.6625
1222 31 May 2012 Telephone Company 145.43 143.216
1227 30 Jun 2012 Telephone Company 147.71 143.965
In this example we calculate 2 running averages which we will call the month-to-date (MTD) running average and the year-to-date (YTD) running average.
SELECT num_check as [check]
,cast(convert(varchar, date_check, 106) as char(11)) as date_check
,cast(payee as char(20)) as payee
,amt_check
,ROUND(wct.RunningAvg(amt_check, ROW_NUMBER() OVER (PARTITION BY MONTH(date_check) ORDER BY num_check),1) ,2) as [MTD AVG]
,ROUND(wct.RunningAvg(amt_check,num_check,NULL), 2) as [YTD AVG]
FROM #c
ORDER BY num_check
This produces the following result.
check date_check payee amt_check MTD AVG YTD AVG
----- ----------- -------------------- --------- ------- -------
1200 31 Jan 2012 Gas Company 108.49 108.49 108.49
1201 31 Jan 2012 Electric Company 98.27 103.38 103.38
1202 31 Jan 2012 Telephone Company 136.60 114.45 114.45
1203 31 Jan 2012 Car Leasing Company 361.75 176.28 176.28
1204 31 Jan 2012 Mortgage Bank 1129.23 366.87 366.87
1205 29 Feb 2012 Gas Company 153.89 153.89 331.37
1206 29 Feb 2012 Electric Company 121.99 137.94 301.46
1207 29 Feb 2012 Telephone Company 138.92 138.27 281.14
1208 29 Feb 2012 Car Leasing Company 361.75 194.14 290.1
1209 29 Feb 2012 Mortgage Bank 1129.23 381.16 74.01
1210 31 Mar 2012 Gas Company 70.79 70.79 346.45
1211 31 Mar 2012 Electric Company 93.57 82.18 325.37
1212 31 Mar 2012 Telephone Company 149.78 104.71 311.87
1213 31 Mar 2012 Car Leasing Company 361.75 168.97 315.43
1214 31 Mar 2012 Mortgage Bank 1129.23 361.02 369.68
1215 30 Apr 2012 Gas Company 105.58 105.58 353.18
1216 30 Apr 2012 Electric Company 149.36 127.47 341.19
1217 30 Apr 2012 Telephone Company 145.35 133.43 330.31
1218 30 Apr 2012 Car Leasing Company 361.75 190.51 331.96
1219 30 Apr 2012 Mortgage Bank 1129.23 378.25 371.83
1220 31 May 2012 Gas Company 96.27 96.27 358.7
1221 31 May 2012 Electric Company 114.62 105.44 347.61
1222 31 May 2012 Telephone Company 145.43 118.77 338.82
1223 31 May 2012 Car Leasing Company 361.75 179.52 339.77
1224 31 May 2012 Mortgage Bank 1129.23 369.46 371.35
1225 30 Jun 2012 Gas Company 147.03 147.03 362.72
1226 30 Jun 2012 Electric Company 130.52 138.78 354.12
1227 30 Jun 2012 Telephone Company 147.71 141.75 346.75
1228 30 Jun 2012 Car Leasing Company 361.75 196.75 347.27
1229 30 Jun 2012 Mortgage Bank 1129.23 383.25 373.34