At times, you may want to replace null values with either a zero or blank, so that analytics work properly. You can do so with the Replace Nulls command. To replace nulls, select the column for which you want to replace nulls and enter the new character for the null.
To enter replace nulls with an empty value, select the replacement field and hit the space bar once. Once you do so, a suggestion appears reading "Replace NULLS in [column] with Empty"