December 2002
Intermediate to advanced
928 pages
85h 29m
English
Most aggregate functions optionally accept the DISTINCT and ALL keywords in their parameter list. These keywords allow you to control the manner in which duplicate column values are handled. The keywords have the following meanings:
Causes the aggregate function to look only at distinct values, and to ignore duplicates.
Causes the aggregate function to look at all values including any duplicates. This is the default behavior.