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Saturday 20 April 2013

TeraData SUM OVER function - Calculating Grand Totals and Subtotals


WITH... BY is used to create subtotals.
WITH is used to create grand totals.

WITH..BY and WITH are both Teradata features and cannot produce relational result.

We can set similar result using SUM window functions:

Generating Sub totals using ANSI SUM window function and Teradata WITH..BY :

Following is how we generate subtotals using the WITH .. BY feature:

select departmentNo, Employeeid, Salary
FROM EMPLOYEE
WITH SUM(salary) BY departmentno;

 *** Query completed. 18 rows found. 3 columns returned.
 *** Total elapsed time was 1 second.


DepartmentNo   Employeeid      Salary
------------  -----------  ----------
         100            1     1000.00
         100            9     9000.00
         100            5     5000.00
                           ----------
              Sum(Salary)    15000.00

         200          124    12345.11
         200            2     2000.00
         200            6     6000.00
         200           10    10000.00
                           ----------
              Sum(Salary)    30345.11

         300            3     3000.00
         300            7     7000.00
         300           11    11000.00
                           ----------
              Sum(Salary)    21000.00

         400            8     8000.00
         400            4     4000.00
         400           12    12000.00
         400          144    12345.11
                           ----------
              Sum(Salary)    36345.11

Thus we get SUM of salaries per department. But this result is not relational and hence this query cannot be used from SQL assistant.

Following is how we make use of ANSI standard SUM OVER() function to get sub totals:

select
departmentNo,
Employeeid,
Salary,
SUM(salary) OVER( PARTITION BY departmentNo
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
FROM EMPLOYEE
;


DepartmentNo
Employeeid
Salary
Group Sum(Salary)
100
1
1000
15000
100
5
5000
15000
100
9
9000
15000
200
124
12345.11
30345.11
200
2
2000
30345.11
200
6
6000
30345.11
200
10
10000
30345.11
300
3
3000
21000
300
7
7000
21000
300
11
11000
21000
400
4
4000
36345.11
400
8
8000
36345.11
400
12
12000
36345.11
400
144
12345.11
36345.11

Each row gets the count of its group.
The PARTITION BY clause does the work of creating groups, same as what WITH BY does.


SUM window functions and other aggregate functions cannot be combined with normal aggregate functions.

Generating Grand Totals using ANSI SUM window function and Teradata WITH:


Following is how we generate grand totals using Teradata 'WITH' functionality:

select
DepartmentNo,
Employeeid,
Salary
FROM EMPLOYEE
WITH SUM(salary);

 *** Query completed. 15 rows found. 3 columns returned.
 *** Total elapsed time was 1 second.


DepartmentNo   Employeeid      Salary
------------  -----------  ----------
         200          124    12345.11
         400            8     8000.00
         200            2     2000.00
         200            6     6000.00
         400            4     4000.00
         400           12    12000.00
         100            1     1000.00
         300            3     3000.00
         200           10    10000.00
         300            7     7000.00
         300           11    11000.00
         100            9     9000.00
         100            5     5000.00
         400          144    12345.11
                           ----------
              Sum(Salary)   102690.22

Following is how we get a similar result using the ANSI standard SUM OVER() function:

select
departmentNo,
Employeeid,
Salary,SUM(salary) OVER(
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
FROM EMPLOYEE
;

DepartmentNo
Employeeid
Salary
Group Sum(Salary)
100
1
1000
102690.2
100
5
5000
102690.2
100
9
9000
102690.2
200
2
2000
102690.2
200
6
6000
102690.2
200
10
10000
102690.2
200
124
12345.11
102690.2
300
3
3000
102690.2
300
7
7000
102690.2
300
11
11000
102690.2
400
4
4000
102690.2
400
8
8000
102690.2
400
12
12000
102690.2
400
144
12345.11
102690.2

2 comments:

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