Aggregate Functions

[This is preliminary documentation and subject to change.]

DBOP_min, DBOP_max, DBOP_count, DBOP_sum, DBOP_avg, DBOP_any_sample, DBOP_stddev, DBOP_stddev_pop, DBOP_var, DBOP_var_pop, DBOP_first, DBOP_last

Aggregate functions, to be used in the aggregation operation, including standard deviation and variance for samples (using division by "N-1") and complete populations (division by "N"). All operators (except count) take one mandatory input representing a column_name on which the function will be computed. A count node with no inputs indicates SQL's COUNT(*). The DISTINCT and ALL SQL set quantifiers, e.g., SELECT SUM (DISTINCT X) FROM T, SELECT SUM (ALL X) FROM T), are indicated by setting the appropriate bits of the dwSetQuantifier field of DBSETFUNC struct as follows:

#define DBSETFUNC_NONE        = 0x00,
#define DBSETFUNC_ALL         = 0x01,
#define DBSETFUNC_DISTINCT    = 0x02
 

The node produces a scalar output.