The LONG NVARCHAR data type stores Unicode character data of arbitrary length.
The maximum size is 2 GB.
Characters are stored in UTF-8. Each character requires from one to four bytes. The maximum number of characters that can be stored in a LONG NVARCHAR is over 500 million and possibly over 2 billion, depending on the lengths of the characters stored.
When an embedded SQL client performs a DESCRIBE on a LONG NVARCHAR column, the data type returned is either DT_LONGVARCHAR or DT_LONGNVARCHAR, depending on whether the db_change_nchar_charset function has been called. See db_change_nchar_charset function.
For ODBC, a LONG NVARCHAR expression is described as SQL_WLONGVARCHAR.
SQL/2003 Vendor extension.