questions about chi square and g test

Hi,
I am new to statistics. I got couple questions about chi square and g
independence test. For chi square test, how do I handle all zero
columns in cross tables? Should those columns be included in the
table? all zero columns will give zero expectation for cells in those
columns and cause divided by zero errors.. For g test, what to do if
some cells have zero observations? That will cause log of zero error.

Thanks.