http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/sql_elements2a.htm 2. VARCHAR2(size) [BYTE | CHAR] Variable-length character string having maximum length size bytes or characters. Maximum size is 4000 bytes, and minimum is 1 byte or 1 character. You must specify size for VARCHAR2. BYTE indicates that the column will have byte length semantics; CHAR indicates that the column will have character semantics.
NVARCHAR2(size) Variable-length character string having maximum length size characters. Maximum size is determined by the national character set definition, with an upper limit of 4000 bytes. You must specify size for NVARCHAR2.
2. VARCHAR2(size) [BYTE | CHAR]
Variable-length character string having maximum length size bytes or characters. Maximum size is 4000 bytes, and minimum is 1 byte or 1 character. You must specify size for VARCHAR2. BYTE indicates that the column will have byte length semantics; CHAR indicates that the column will have character semantics.
NVARCHAR2(size)
Variable-length character string having maximum length size characters. Maximum size is determined by the national character set definition, with an upper limit of 4000 bytes. You must specify size for NVARCHAR2.