问在Postgres 8.2函数中传递参数会导致数组错误

EN

/*
@Function: valiDates [Avoid inserting data from invalid dates]
@Purpose: Providing a _TABLE and a date _COLUMN to be validated.
Given a _DATE (from script name) validate that a certain % of data (_TOLERANCE) belongs to the _INTERVAL of days specified.
*/

CREATE OR REPLACE FUNCTION valiDates(_date date, _table regclass, _column text, _interval integer,  _tolerance real) RETURNS BOOLEAN AS
$$
DECLARE result boolean;
BEGIN
    EXECUTE 'SELECT
            (SELECT count(*) FROM ' || _table::regclass || '
             WHERE ' || _column || ' BETWEEN '''|| _date || '''::date and ''' || _date || '''::date + INTERVAL ''' ||  _interval || 'days'')'
                        || '/
            (SELECT COUNT(*) FROM ' || _table::regclass || ')::real
         > ' || _tolerance
    INTO result;
    RETURN result;
END
;
$$ LANGUAGE plpgsql;

select valiDates('2015-03-01','_table','_date',1,0.8);