New syntax:

CREATE TABLE t1(a NVARCHAR(10))
This is for compatibility with MSSQL, DB2, Informix and some other DBMSs.

Note, standard SQL doesn't have "NVARCHAR" syntax.
There are only these syntaxes in SQL2003:
 NATIONAL VARCHAR
 NCHAR VARCHAR
 NATIONAL CHARACTER VARYING 
 NCHAR VARYING

- Tests were added for all the above syntaxes.

mysql-test/t/type_nchar.test

+#
+# Test nchar/nvarchar
+#
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+create table t1 (c nchar(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c national char(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c national varchar(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c nvarchar(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c nchar varchar(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c national character varying(10));
+show create table t1;
+drop table t1;
+
+create table t1 (c nchar varying(10));
+show create table t1;
+drop table t1;
+

sql/lex.h

@@ -293,6 +293,7 @@ static SYMBOL symbols[] = {
   { "NOT",		SYM(NOT),0,0},
   { "NULL",		SYM(NULL_SYM),0,0},
   { "NUMERIC",		SYM(NUMERIC_SYM),0,0},
+  { "NVARCHAR",		SYM(NVARCHAR_SYM),0,0},
   { "OFFSET",		SYM(OFFSET_SYM),0,0},
   { "OLD_PASSWORD",	SYM(OLD_PASSWORD),0,0},
   { "ON",		SYM(ON),0,0},

sql/sql_yacc.yy

@@ -302,6 +302,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	NEW_SYM
 %token	NCHAR_SYM
 %token	NCHAR_STRING
+%token  NVARCHAR_SYM
 %token	NOT
 %token	NO_SYM
 %token	NULL_SYM
@@ -1339,6 +1340,7 @@ varchar:
 
 nvarchar:
 	NATIONAL_SYM VARCHAR {}
+	| NVARCHAR_SYM {}
 	| NCHAR_SYM VARCHAR {}
 	| NATIONAL_SYM CHAR_SYM VARYING {}
 	| NCHAR_SYM VARYING {}
@@ -4568,6 +4570,7 @@ keyword:
 	| NEW_SYM		{}
 	| NO_SYM		{}
 	| NONE_SYM		{}
+	| NVARCHAR_SYM		{}
 	| OFFSET_SYM		{}
 	| OLD_PASSWORD		{}
 	| OPEN_SYM		{}