Oracle在PostgreSQL中“使用”聚合[重复]

Question

此问题已经在这里有了答案：

How to concatenate strings of a string field in a PostgreSQL 'group by' query?（14个回答）

[<14天前关闭。

我想知道PostgreSQL中的Oracle“ Aggregate Using”是否有其他选择？

CREATE OR REPLACE TYPE type_1 AS OBJECT (   g_string  VARCHAR2(32767),

  STATIC FUNCTION ODCIAggregateInitialize(sctx  IN OUT  t_string_agg)
    RETURN NUMBER,

  MEMBER FUNCTION ODCIAggregateIterate(self   IN OUT  t_string_agg,
                                       value  IN      VARCHAR2 )
     RETURN NUMBER,

  MEMBER FUNCTION ODCIAggregateTerminate(self         IN  
t_string_agg,
                                         returnValue  OUT  VARCHAR2,
                                         flags        IN   NUMBER)
    RETURN NUMBER,

  MEMBER FUNCTION ODCIAggregateMerge(self  IN OUT  t_string_agg,
                                     ctx2  IN      t_string_agg)
    RETURN NUMBER ); /



CREATE OR REPLACE TYPE BODY t_string_agg IS   STATIC FUNCTION
ODCIAggregateInitialize(sctx  IN OUT  t_string_agg)
    RETURN NUMBER IS   BEGIN
    sctx := t_string_agg(NULL);
    RETURN ODCIConst.Success;   END;

  MEMBER FUNCTION ODCIAggregateIterate(self   IN OUT  t_string_agg,
                                       value  IN      VARCHAR2 )
    RETURN NUMBER IS   BEGIN
    SELF.g_string := self.g_string || ',' || value;
    RETURN ODCIConst.Success;   END;

  MEMBER FUNCTION ODCIAggregateTerminate(self         IN  
t_string_agg,
                                         returnValue  OUT  VARCHAR2,
                                         flags        IN   NUMBER)
    RETURN NUMBER IS   BEGIN
    returnValue := SUBSTR(SELF.g_string, 2);
    RETURN ODCIConst.Success;   END;

  MEMBER FUNCTION ODCIAggregateMerge(self  IN OUT  t_string_agg,
                                     ctx2  IN      t_string_agg)
    RETURN NUMBER IS
      BEGIN
    SELF.g_string := SELF.g_string || ctx2.g_string;
    RETURN ODCIConst.Success;   END; END; /


CREATE OR REPLACE FUNCTION string_agg (p_input VARCHAR2) RETURN
VARCHAR2 AGGREGATE USING t_string_agg;

Answer 1

您可以使用create aggregate语法在PostgreSQL中定义自定义聚合函数。