date calculation

//mySQL


SELECT CURDATE( )
-------------------
CURDATE( )
2011-12-29

SELECT CURDATE( ) -1
-------------------
CURDATE( ) -1
20111228

SELECT now( )
-------------------
now( )
2011-12-29 10:29:31

SELECT now( )-1
-------------------
now( )-1
20111229104426.000000