SQL-Doesn't return a value when the columns are multiplied

Question

I have 3 columns in my db table, I need to multiply column, itm_count & itm_price and output the total for a given id(itm_id).

SELECT sum(itm_price * itm_count) as total FROM ods_temporder WHERE itm_id='11'

I tried to do this using the above sql query, but the result was null. What seems to be the issue here?

Answer 1

What do this give you?

SELECT itm_price, itm_count FROM ods_temporder WHERE itm_id='11'

Is either of itm_price or itm_count NULL? Do you have rows for itm_id = 11?