how to swap two column value in mysql query

see the example how to swap  column rows value

UPDATE emprs SET EName=(@temp:=EName), EName= Salary, Salary = @temp;
or
UPDATE emprs s1, emprs s2 SET s1.EName=s1.Salary, s1.Salary=s2.EName WHERE s1.id=s2.id;

How does we check the product page in wordpress

 if (is_single() && get_post_type()== 'wpsc-product' ) {
echo "its a product pag";
}else{
echo "it is not product page";
}?>