SQLServer,MySQL,Oracle,PostgreSQL中常用函数用法（1）日

SELECT DAYNAME('1998-02-03');
->'周四'

SELECT TO_CHAR(SYSDATE, 'Day') 
FROM dual;

SELECT DATE_PART('dow', date 'now');

SELECT DATADIFF(dd,'1/1/01',GETDATE())
GO

SELECT FROM_DAYS(TO_DAYS(CURDATE()) - TO_DAYS('2012-12-05'));

SELECT TO_DATE('25-Nov-2000','dd-mon-yyyy') - TO_DATE('25-Aug-1969','dd-mon-yyyy')
FROM dual;

SELECT AGE(CURRENT_DATE,'25-Aug-1969');

SELECT CONVERT(VARCHAR(11),GETDATE(),102)
GO

SELECT DATE_FORMAT("2001-11-25","%M %E,%Y");

ELECT TO_CHAR(SYSDATE,'dd-Mon-yyyy hh:mi,ss PM')
FROM dual;

SELECT TO_CHAR(timestamp(CURRENT_DATE),'dd-Mon-yyyy hh:mi:ss PM')