SQL ANSI/ISO Data Types(SQL数据类型及对应关系)

本章枚举并说明SQL ISO规范中给定的数据类型，并列出JDBC规范及Oracle、SQLServer对应的数据类型。

大类	ISO/ANSI	JDBC	Oracle	SQLServer	MySQL	PostgreSQL
文本	CHARACTER(n)	CHAR	CHAR	char
	CHARACTER VARYING(n)	VARCHAR	VARCHAR (VARCHAR2)	varchar
	CHARACTER LARGE OBJECT	CLOB	CLOB	text
	NATIONAL CHARACTER(n)	NCHAR	NCHAR	nchar
	NATIONAL CHARACTER VARYING(n)	NVARCHAR	NVARCHAR (NVARCHAR2)	nvarchar
	NATIONAL CHARACTER LARGE OBJECT	NCLOB	NCLOB	ntext
字节	BINARY(n)	BINARY	×	binary
	BINARY VARYING(n)	VARBINARY	×	varbinary
	BINARY LARGE OBJECT	BLOB	BLOB	image
整形	SMALLINT	SMALLINT	NUMBER(5)	smallint
	INTEGER	INTEGER	NUMBER(10)	int
	BIGINT	BIGINT	NUMBER(38)	bigint
数值	DECIMAL	DECIMAL	DECIMAL (NUMBER)	decimal
	NUMERIC	NUMERIC	NUMERIC (NUMBER)	numeric
	REAL	REAL	REAL	real
	FLOAT	FLOAT	FLOAT BINARY_FLOAT	float
	DOUBLE PRECISION	DOUBLE	DOUBLE BINARY_DOUBLE
	DECFLOAT	×	×	×
布尔	BOOLEAN	BOOLEAN	×	bit
日期	DATE	DATE	DATE	date
	TIME WITHOUT TIME ZONE	TIME	DATE	time
	TIME WITH TIME ZONE	TIME_WITH_TIMEZONE	DATE	time
	TIMESTAMP WITHOUT TIME ZONE	TIMESTAMP	TIMESTAMP	timestamp
	TIMESTAMP WITH TIME ZONE	TIMESTAMP_WITH_TIMEZONE	TIMESTAMP	timestamp
	INTERVAL	×

其中Oracle数据类型，参见https://my.oschina.net/jixiaolei/blog/4816208