The aggregate functions generate summary values that appear as new columns in the query results. The aggregate functions are:
Aggregate functions can be used in the select list or the having clause of a select statement or subquery. They cannot be used in a where clause.
Each aggregate in a query requires its own worktable. Therefore, a query using aggregates cannot exceed the maximum number of worktables allowed in a query (12).
When an aggregate function is applied to a char datatype value, it implicitly converts the value to varchar, stripping all trailing blanks. Likewise, a unichar datatype value is implicitly converted to univarchar.
The max, min, and count aggregate functions now have semantics that include the unichar data type.