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Aggregate Functions

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The following list describes the operators for aggregate functions.

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

These are 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 is computed. A count node with no inputs indicates SQL's COUNT(*). The DISTINCT and ALL SQL set quantifiers; for example, SELECT SUM (DISTINCT X) FROM T, SELECT SUM (ALL X) FROM T) are indicated by setting the appropriate bits of the dwSetQuantifier member of the DBSETFUNC structure using the aggregate function constants. The node produces a scalar output.