Missing mySQL variables

I have been creating a PHP form which reads a record and puts the values into the 'values=' part of the HTML <INPUT> tag. Unfortunatelym when I use mySQL adn the array_fetch command, if the column is NULL then if you try to access the particular column using @row["nullcolumn"] you just get an unidentified index error. There seem unfortunately no way around it. Can any one please help?

if(isset(row["nullcolumn"])) {
//do something
}

??