There a couple of ways you can do this, one by using the function ‘COALESCE’ and the other one is using CASE expression.
COALESCE is a simple function which takes one or more column names and a replacement (default) value which can be displayed in case of the missing data.  For example, in an employee table [...]

Popularity: 45% [?]

This is a very common problem while displaying some numbers (numeric values) using the format function in Teradata. Instead of the numbers, you would see a bunch of wild char characters (‘*’); If you run the following SQL in Teradata SQL Assistant Version 7.1
SELECT cast ((545458874489 (format ‘999-999-9999′)) as char (15)) as Format_Cast_PhoneNum
Output would be [...]

Popularity: 17% [?]