Help with Sql commands

[c0ncrete]

yes, * is the multiplication operator.
you might consider updating each stat individually, as tabasco suggested, to keep from multiplying negative values:

UPDATE items SET CR=CR*5 WHERE CR > 0;

that would only multiply positive CR values.

additionally, you could run something like this:

UPDATE items SET CR=0 WHERE CR < 0;

to set any negative CR values to 0.