CREATE OR REPLACE FUNCTION timeadd(difftype character varying, incrementvalue integer, inputdate timestamp with time zone) RETURNS timestamp without time zone AS $BODY$ DECLARE YEAR_CONST Char(15) := 'year'; MONTH_CONST Char(15) := 'month'; WEEK_CONST Char(15) := 'week'; DAY_CONST Char(15) := 'day'; HOUR_CONST Char(15) := 'hour'; MIN_CONST Char(15) :='mi'; SECOND_CONST Char(15) :='ss'; dateTemp timestamp; intervals interval; BEGIN IF lower($1) = lower(YEAR_CONST) THEN select cast(cast(incrementvalue as character varying) || ' year' as interval) into intervals; ELSEIF lower($1) = lower(MONTH_CONST) THEN select cast(cast(incrementvalue as character varying) || ' months' as interval) into intervals; ELSEIF lower($1) = lower(WEEK_CONST) THEN select cast(cast(incrementvalue as character varying) || ' week' as interval) into intervals; ELSEIF lower($1) = lower(DAY_CONST) THEN select cast(cast(incrementvalue as character varying) || ' day' as interval) into intervals; ELSEIF lower($1) = lower(HOUR_CONST) THEN select cast(cast(incrementvalue as character varying) || ' hour' as interval) into intervals; ELSEIF lower($1) = lower(MIN_CONST) THEN select cast(cast(incrementvalue as character varying) || ' minute' as interval) into intervals; ELSEIF lower($1) = lower(SECOND_CONST) THEN select cast(cast(incrementvalue as character varying) || ' second' as interval) into intervals; END IF; dateTemp:= inputdate + intervals; RETURN dateTemp; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE;
------------------------------------------- API ------------------------------------------------------------
功能:类似于Sybase语法中的dateadd函数,用于时间加减相应的时间段
参数:
- $1 时间运算格式,分为:ss(秒),mi(分钟),hour(小时),day(天),week(周),month(月),year(年)
- $2 时间运算间隔,整型,正负均可
- $3 本地时间,常用now()代替
范例:
select timeadd('day',-1,now())