oracle自定义聚合函数

第一步: 实现 ODCIAggregate 接口(定义type、type body)

CREATE TYPE SpatialUnionRoutines(

STATIC FUNCTION ODCIAggregateInitialize( ... ) ...,

MEMBER FUNCTION ODCIAggregateIterate(...) ... ,

MEMBER FUNCTION ODCIAggregateMerge(...) ...,

MEMBER FUNCTION ODCIAggregateTerminate(...)

);

CREATE TYPE BODY SpatialUnionRoutines IS

...

END;

第2步: 定义自定义函数

CREATE FUNCTION SpatialUnion(x Geometry) RETURN Geometry

AGGREGATE USING SpatialUnionRoutines;

第3: 使用自定义聚合函数

SELECT SpatialUnion(geometry) FROM counties GROUP BY state

下面为具体例子:
1、定义type
create or replace type STRCAT_TYPE as object (
CAT_STRING varchar2(4000),
static Function ODCIAGGREGATEINITIALIZE (CS_CTX IN OUT strcat_type)
return number,
member Function ODCIAGGREGATEITERATE (SELF IN OUT strcat_type,VALUE IN varchar2)
return number,
member Function ODCIAGGREGATEMERGE (SELF IN Out strcat_type,CTX2 IN Out strcat_type)
return number,
member Function ODCIAGGREGATETERMINATE (SELF IN Out strcat_type,RETURNVALUE OUT varchar2,FLAGS IN number)
return number
)
2、定义type body
create or replace type body STRCAT_TYPE as
static Function ODCIAGGREGATEINITIALIZE (CS_CTX IN OUT strcat_type)
return number as
begin
cs_ctx := strcat_type( null );
return ODCIConst.Success;
end;
member Function ODCIAGGREGATEITERATE (SELF IN OUT strcat_type,VALUE IN varchar2)
return number as
begin
--1. concat string
self.cat_string := self.cat_string || ','|| value;
-- 2.get union set
-- if instr(self.cat_string, value ) = 0 or self.cat_string is null then
-- self.cat_string := self.cat_string || ',' || value ;
-- else
-- self.cat_string := self.cat_string ||'' ;
-- end if ;
return ODCIConst.Success;
end;
member Function ODCIAGGREGATEMERGE (SELF IN Out strcat_type,CTX2 IN Out strcat_type)
return number as
begin
self.cat_string := self.cat_string || ',' || ctx2.cat_string;
return ODCIConst.Success;
end;
member Function ODCIAGGREGATETERMINATE (SELF IN Out strcat_type,RETURNVALUE OUT varchar2,FLAGS IN number)
return number as
begin
returnValue := ltrim(rtrim(self.cat_string,','),',');
return ODCIConst.Success;
end;
end;
3、定义函数
CREATE OR REPLACE FUNCTION strcat(input varchar2) RETURN varchar2
PARALLEL_ENABLE
AGGREGATE USING strcat_type;
以上最终效果如下：
附一：具体表结构、数据如下：



附二：具体使用方法如下：