php/mysql table problem

Hi I have the following table (real simple):
CREATE TABLE txttest (comments TEXT);

I then use a <textarea> to enter text.
This text then gets inserted into the table above.

I was told to use: $comments=urlencode($comments);
before inserting into my database

This WORKS when I type in something like:
"this is a comment line" (looks like: this+is+a+comment+line)
BUT
if I type in something like:
"this is a comment line,
this is another comment line"
(looks like: this+is+a+comment+line%2C%0D%0Athis+is+another+comment+line)

I get this error:
Error in executing INSERT INTO txttest (comments)VALUES('this+is+a+comment+line%2C%0D%0Athis+is+another+comment+line')
error:1065 Query was empty

ANY IDEAS??

Thanks
Mike