ORACLE 修改wm_concat逗号分隔符为自定义的符号

本文链接：https://blog.youkuaiyun.com/iilegend/article/details/83344779

本文详细介绍了如何在Oracle中重写wm_concat函数，通过自定义类型MyConcatImpl实现字符串聚合功能，使用'-----'作为分隔符。文章深入探讨了ODCIAggregateInitialize、ODCIAggregateIterate、ODCIAggregateTerminate和ODCIAggregateMerge等成员函数的具体实现，展示了如何创建并使用自定义聚合函数。

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重写wm_concat函数，将分隔符改成 -----（自己定义）

create or replace type MyConcatImpl as object  
(  
  str VARCHAR2(32767), -- second highest value seen so far  
  static function ODCIAggregateInitialize(sctx IN OUT MyConcatImpl)   
    return number,  
  member function ODCIAggregateIterate(self IN OUT MyConcatImpl,   
    value IN VARCHAR2) return number,  
  member function ODCIAggregateTerminate(self IN MyConcatImpl,   
    returnValue OUT VARCHAR2, flags IN number) return number,  
  member function ODCIAggregateMerge(self IN OUT MyConcatImpl,   
    ctx2 IN MyConcatImpl) return number  
);  
/  
  
create or replace type body MyConcatImpl is   
static function ODCIAggregateInitialize(sctx IN OUT MyConcatImpl)   
return number is   
begin  
  sctx := MyConcatImpl(NULL);  
  return ODCIConst.Success;  
end;  
  
member function ODCIAggregateIterate(self IN OUT MyConcatImpl, value IN VARCHAR2) return number is  
begin  
  if self.str is not null then  
    self.str := self.str || '-----' || value;  
  else  
    self.str := value;  
  end if;  
  return ODCIConst.Success;  
end;  
  
member function ODCIAggregateTerminate(self IN MyConcatImpl, returnValue OUT VARCHAR2, flags IN number) return number is  
begin  
  returnValue := self.str;  
  return ODCIConst.Success;  
end;  
  
member function ODCIAggregateMerge(self IN OUT MyConcatImpl, ctx2 IN MyConcatImpl) return number is  
begin  
  if ctx2.str is not null then  
    self.str := self.str || '-----' || ctx2.str;  
  end if;  
  return ODCIConst.Success;  
end;  
end;  
/  
create or replace FUNCTION MyConcat(input VARCHAR2) RETURN VARCHAR2   
PARALLEL_ENABLE AGGREGATE USING MyConcatImpl;

结果为：