正如Erwin所说:日期没有格式。此外,无需对日期进行过多的字符转换。另外,即使对于最终的查询结果,你也可以使用
SET datestyle;
(针对最常用的样式),避免所有过度的格式化。
DROP SCHEMA tmp CASCADE;
CREATE SCHEMA tmp ;
SET search_path=tmp;
CREATE TABLE SYS_FEED
( USERID INTEGER NOT NULL PRIMARY KEY
, GRANTDATE DATE NOT NULL
, REVOKEDATE DATE NOT NULL
, feedname varchar
);
INSERT INTO SYS_FEED(USERID, GRANTDATE, REVOKEDATE, feedname)
SELECT sv
, date('2005-01-01') + sv
, date('2006-01-01') + sv
, 'silent_' || sv::text
FROM generate_series( 1,1000) sv
;
CREATE TABLE PRINCIPLE
( ID INTEGER NOT NULL PRIMARY KEY
, SURNAME varchar
);
INSERT INTO PRINCIPLE(ID,SURNAME)
SELECT val
, 'SHOUT_' || val::text
FROM generate_series( 1,1000) val
;
DELETE FROM SYS_FEED WHERE random() < 0.9;
DELETE FROM PRINCIPLE WHERE random() < 0.9;
SELECT P.SURNAME
, to_char(SFE.GRANTDATE, 'DD Mon YY') AS GRANTDATE
, to_char(SFE.REVOKEDATE, 'DD Mon YY') AS REVOKEDATE
, SFE.feedname AS DONTSHOUTNAME
FROM SYS_FEED SFE
JOIN PRINCIPLE P ON SFE.USERID = P.ID
WHERE GRANTDATE < '2006-12-01'
;
结果:
DROP SCHEMA
CREATE SCHEMA
SET
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "sys_feed_pkey" for table "sys_feed"
CREATE TABLE
INSERT 0 1000
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "principle_pkey" for table "principle"
CREATE TABLE
INSERT 0 1000
DELETE 901
DELETE 904
surname | grantdate | revokedate | dontshoutname
SHOUT_53 | 23 Feb 05 | 23 Feb 06 | silent_53
SHOUT_173 | 23 Jun 05 | 23 Jun 06 | silent_173
SHOUT_308 | 05 Nov 05 | 05 Nov 06 | silent_308
SHOUT_337 | 04 Dec 05 | 04 Dec 06 | silent_337
SHOUT_531 | 16 Jun 06 | 16 Jun 07 | silent_531
SHOUT_543 | 28 Jun 06 | 28 Jun 07 | silent_543
SHOUT_566 | 21 Jul 06 | 21 Jul 07 | silent_566
(7 rows)