Trying to paste:
CREATE TABLE ".$prefix."store_comments (
into phpMyAdmin will fail
phpMyAdmin doesn't interpret your statement as php code, just sends the string to the database.
CREATE TABLE MyPrefixstore_comments (
will work in PHP my admin
or write and execute your own php script:
$prefix='MyPrefix';
$result=mysql_query ("CREATE TABLE ".$prefix."store_comments (
name varchar(100) NOT NULL,
product varchar(60) NOT NULL default '',
stars tinyint(1) DEFAULT '0' NOT NULL,
status tinyint(1) DEFAULT '0' NOT NULL,
comments text NOT NULL,
id int(60) NOT NULL auto_increment,
PRIMARY KEY (id))");