Excerpt 

Aggregate functions perform a computation against a set of values to generate a single result. For example, you could use an aggregate function to compute the average (mean) order over a period of time. Aggregations can be applied as standard functions or used as part of a transformation step to reshape the data. 
Aggregate across an entire column:
D trans  


Output: Generates a new column containing the average of all values in the Scores
column.
D trans  


Output: Generates a singlecolumn table with a single value, which contains the average of all values in the Scores
column. The limit defines the maximum number of columns that can be generated.
Info 

NOTE: When aggregate functions are applied as part of a pivot transformation, they typically involve multiple parameters as part of an operation to reshape the dataset. See below. 
Aggregate across groups of values within a column:
Aggregate functions can be used with the pivot transformation to change the structure of your data. Example:
D trans  


In the above instance, the resulting dataset contains two columns:
studentId
 one row for each distinct student ID valueaverage_Scores
 average score by each student (studentId
)
Info 

NOTE: You cannot use aggregate functions inside of conditionals that evaluate to 
A pivot transformation can include multiple aggregate functions and group columns from the preaggregate dataset.
For more information on the transformation, see Pivot Data.
Info 

NOTE: Null values are ignored as inputs to these functions. 
These aggregate functions are available:
D children  

