SQL方言参考

SQL version	Feature	Standard SQL:2011	DB2	Firebird	Ingres	Linter	MSSQL	MySQL	MonetDB	Oracle Vers. 11.x	PostgreSQL	SQLite	Virtuoso
?	Variable-length with limit	VARCHAR	VARCHAR	VARCHAR	VARCHAR NVARCHAR	VARCHAR NVARCHAR	VARCHAR[(n or max)] NVARCHAR[(n or max)]	VARCHAR	VARCHAR CHARACTER VARYING	VARCHAR2 VARCHAR is slated for deprecation	character varying varchar	TEXT[1]	VARCHAR
?	Variable-length with limit, max size	no limit	?	32765	?	?	2 GB with (max) or 8000 with the fixed limit	65535	about 2 GB	4000 bytes (32767 bytes if MAX_STRING_SIZE = EXTENDED - Oracle 12G)	about 1 GB	no limit (enforced by global, default = 1M)	?
?	Fixed-length, blank padded string	CHAR	CHAR	CHAR	CHAR NCHAR	CHAR NCHAR	CHAR NCHAR	CHAR	?	CHAR	character char	N/A	CHAR
?	Fixed-length, blank padded string, max size	no limit	?	32767	?	?	8000	255	?	2000	about 1 GB	N/A	?

Notes:

1. ↑ uses dynamic typing; allows any type name