创建用户定义的聚合函数来计算加权平均值:
CREATE OR REPLACE TYPE WEIGHTED_AVG_O AS OBJECT (
sum_of_weights NUMBER,
sum_of_weights_times_value NUMBER,
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(cs_ctx IN OUT WEIGHTED_AVG_O) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEITERATE (self IN OUT WEIGHTED_AVG_O, value IN WEIGHTED_AVG_O) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEMERGE (self IN OUT WEIGHTED_AVG_O, ctx2 IN OUT WEIGHTED_AVG_O) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATETERMINATE (self IN OUT WEIGHTED_AVG_O, returnvalue OUT NUMBER, flags IN NUMBER) RETURN NUMBER
);
/
CREATE OR REPLACE TYPE BODY WEIGHTED_AVG_O
AS
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(cs_ctx IN OUT WEIGHTED_AVG_O) RETURN NUMBER
IS
BEGIN
cs_ctx := WEIGHTED_AVG_O(0, 0);
RETURN odciconst.success;
END;
MEMBER FUNCTION ODCIAGGREGATEITERATE (self IN OUT WEIGHTED_AVG_O, value IN WEIGHTED_AVG_O) RETURN NUMBER
IS
BEGIN
self.sum_of_weights := self.sum_of_weights + value.sum_of_weights;
self.sum_of_weights_times_value := self.sum_of_weights_times_value + value.sum_of_weights * value.sum_of_weights_times_value;
RETURN odciconst.success;
END;
MEMBER FUNCTION ODCIAGGREGATEMERGE (self IN OUT WEIGHTED_AVG_O, ctx2 IN OUT WEIGHTED_AVG_O) RETURN NUMBER
IS
BEGIN
RETURN odciconst.success;
END;
MEMBER FUNCTION ODCIAGGREGATETERMINATE (self IN OUT WEIGHTED_AVG_O, returnvalue OUT NUMBER, flags IN NUMBER) RETURN NUMBER
IS
BEGIN
IF sum_of_weights = 0 THEN
returnvalue := NULL;
ELSE
returnvalue := sum_of_weights_times_value/sum_of_weights;
END IF;
RETURN odciconst.success;
END;
END;
/
CREATE OR REPLACE FUNCTION WEIGHTED_AVG (input WEIGHTED_AVG_O)
RETURN NUMBER PARALLEL_ENABLE
AGGREGATE USING WEIGHTED_AVG_O;
/
查询与您的数据:
SELECT part, WEIGHTED_AVG(WEIGHTED_AVG_O(qty, price_per))
FROM <YOUR_TABLE>
GROUP BY part;
猜你不需要TOTAL_QTY字段了。它公然违反了唯一性数据原则 - 每一条数据只能出现一次。 – Josep 2013-05-29 13:05:14