Create an Oracle function that returns a table

问题:

I'm trying to create a function in package that returns a table. I hope to call the function once in the package, but be able to re-use its data mulitple times. While I know I create temp tables in Oracle, I was hoping to keep things DRY.

So far, this is what I have:

Header:

CREATE OR REPLACE PACKAGE TEST AS 

    TYPE MEASURE_RECORD IS RECORD (
      L4_ID VARCHAR2(50),
      L6_ID VARCHAR2(50),
      L8_ID VARCHAR2(50),
      YEAR NUMBER,
      PERIOD NUMBER,
      VALUE NUMBER
    );

    TYPE MEASURE_TABLE IS TABLE OF MEASURE_RECORD;

    FUNCTION GET_UPS(
      TIMESPAN_IN IN VARCHAR2 DEFAULT 'MONTLHY',
      STARTING_DATE_IN DATE,
      ENDING_DATE_IN DATE  
    ) RETURN MEASURE_TABLE;

END TEST;

Body:

CREATE OR REPLACE PACKAGE BODY TEST AS 

  FUNCTION GET_UPS (
    TIMESPAN_IN IN VARCHAR2 DEFAULT 'MONTLHY',
    STARTING_DATE_IN DATE,
    ENDING_DATE_IN DATE
  ) RETURN MEASURE_TABLE IS

    T MEASURE_TABLE;

  BEGIN

        SELECT  ...
        INTO    T
        FROM    ...

      ;

  RETURN T;

  END GET_UPS;

END TEST;

The header compiles, the body does not. One error message is 'not enough values', which probably means that I should be selecting into the MEASURE_RECORD, rather than the MEASURE_TABLE.

What am I missing?

回答1:

I think you want a pipelined table function.

Something like this:

CREATE OR REPLACE PACKAGE test AS

    TYPE measure_record IS RECORD(
       l4_id VARCHAR2(50), 
       l6_id VARCHAR2(50), 
       l8_id VARCHAR2(50), 
       year NUMBER, 
       period NUMBER,
       VALUE NUMBER);

    TYPE measure_table IS TABLE OF measure_record;

    FUNCTION get_ups(foo NUMBER)
        RETURN measure_table
        PIPELINED;
END;

CREATE OR REPLACE PACKAGE BODY test AS

    FUNCTION get_ups(foo number)
        RETURN measure_table
        PIPELINED IS

        rec            measure_record;

    BEGIN
        SELECT 'foo', 'bar', 'baz', 2010, 5, 13
          INTO rec
          FROM DUAL;

        -- you would usually have a cursor and a loop here   
        PIPE ROW (rec);

        RETURN;
    END get_ups;
END;

For simplicity I removed your parameters and didn't implement a loop in the function, but you can see the principle.

Usage:

SELECT *
  FROM table(test.get_ups(0));



L4_ID L6_ID L8_ID       YEAR     PERIOD      VALUE
----- ----- ----- ---------- ---------- ----------
foo   bar   baz         2010          5         13
1 row selected.

回答2:

To return the whole table at once you could change the SELECT to:

SELECT  ...
BULK COLLECT INTO T
FROM    ...

This is only advisable for results that aren't excessively large, since they all have to be accumulated in memory before being returned; otherwise consider the pipelined function as suggested by Charles, or returning a REF CURSOR.

回答3:

  CREATE OR REPLACE PACKAGE BODY TEST AS 

   FUNCTION GET_UPS(
   TIMESPAN_IN IN VARCHAR2 DEFAULT 'MONTLHY',
   STARTING_DATE_IN DATE,
   ENDING_DATE_IN DATE
   )RETURN MEASURE_TABLE IS

    T MEASURE_TABLE;

 BEGIN

    **SELECT   MEASURE_RECORD(L4_ID , L6_ID ,L8_ID ,YEAR ,
             PERIOD,VALUE )  BULK COLLECT  INTO    T
    FROM    ...**

  ;

   RETURN T;

   END GET_UPS;

END TEST;