Hello, i have a table and use a cursor to prove the rows and do some changes (for example take value from row n+1 for row n). To perform a faster select query i insert some informations about the row. For example: CUSTOMER_ID | DATE | ..... | BUYS_OFTEN | GOOD_FEEDBACK 12 | 2008-01-01 | ...... | 1 | 1 12 | 2008-01-01 | ...... | 0 | NULL 13 | 2008-01-01 | ...... | 1 | 0 As you see in the row with ID 13 i wrote the 2 possiblities i thought about. There are rows where this information is not needed (the infos are just needed for the first date entry for a specific customer) therefore i have to NULL the fields there or insert a def value. The question is what's better? In the first case (NULL) i have to write SELECT WHERE IS NOT NULL and in the second case (def value) i have to write SELECT WHERE IS (1) Thx for your opinions.