Looping through a postgres table and returning the wekid

问题

I have a requirement to loop through a table having all the reporting periods right from 2010. I need to loop through this table so that i when I pass the date string, it takes at and compares it if it is less than the reporting_periods_o and returns back the reporting_period_string.

CREATE OR REPLACE FUNCTION rpt.reportingperiods(IN v_date text)
 RETURNS SETOF text AS
 $BODY$
 DECLARE

v_in_date INT := CAST(v_date AS INT);
i     INT;
v_sk       INT;

BEGIN
For i IN SELECT rpt_sk FROM rpt.REPORTING_PERIODS LOOP 
    SELECT rpt_sk INTO v_sk FROM rpt.REPORTING_PERIODS  where rpt_sk = i;
    IF v_in_date <= (SELECT reporting_periods_o FROM rpt.REPORTING_PERIODS
               WHERE rpt_sk = i) 
    THEN RETURN QUERY SELECT MIN(reporting_periods)reporting_periods FROM rpt.REPORTING_PERIODS WHERE rpt_sk =  v_sk AND CAST(reporting_periods AS DATE) > CAST(now() AS DATE);
    END IF;
END LOOP;

END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100
ROWS 1000;

My reporting periods has three fields:

 rpt_sk, reporting_periods, reporting_periods_o
  1          2014-03-08          20140308

I have implemented a function but when I execute I am getting multiple records, I need to be able to get back one record.

来源：https://stackoverflow.com/questions/23301082/looping-through-a-postgres-table-and-returning-the-wekid