What does it mean?

[Kostas Tsirigos]

Hello to everyone!
I am just beggining using MySQL in order to create a database.
I want to create this table:

id(PRIMARY KEY) name(text,unique) link(text,unique)


I use this syntax :

create table test
(id int primary key auto_increment,
name varchar(100) not null unique,
link varchar(1000) not null unique);

In this syntax, I get the message: ERROR 1170(42000): BLOB/TEXT column 'link'
used in key specification without a key length.

If I use this syntax:
create table test
(id int primary key auto_increment,
name varchar(100) not null unique,
link varchar(1000) not null);

everything is OK. Why can't I use unique twice? Or is there anything else wrong
in the first syntax???

Thank you very much