各种数据库的数据类型对比

	postgresql	sqlite	sqlserver	sybase	db2	mysql	openbase	oracle
binary	bytea	blob	image	image	blob(32768)	blob	object	blob
boolean	boolean	boolean	bit	bit	decimal(1)	tinyint(1)	boolean	number(1)
date	date	date	datetime	datetime	date	date	date	date
datetime	timestamp	datetime	datetime	datetime	timestamp	datetime	datetime	date
decimal	decimal	decimal	decimal	decimal	decimal	decimal	decimal	decimal
float	float	float	float(8)	float(8)	float	float	float	number
integer	integer	integer	int	int	int	int(11)	integer	number(38)
string	(note 1)	varchar(255)	varchar(255)	varchar(255)	varchar(255)	varchar(255)	char(4096)	varchar2(255)
text	text	text	text	text	clob(32768)	text	text	clob
time	time	datetime	datetime	time	time	time	time	date
timestamp	timestamp	datetime	datetime	timestamp	timestamp	datetime	timestamp	date

reference:
http://www.blogjava.net/GavinMiao/archive/2011/09/06/358081.html
http://blog.csdn.net/dengxingbo/article/details/5896314
http://onlamp.com/onlamp/2001/09/13/aboutSQL.html
http://www.java2s.com/Code/Java/Hibernate/JavaTypeVSHibernateType.htm