Applying the select list

The results of applying the select list to R depend on whether GROUP BY or HAVING is used:

If GROUP BY or HAVING is used

• Each column-name in the select list must identify a grouping expression, or be specified within an aggregate function, or be a correlated reference:
  • If the grouping expression is a column name, the select list may apply additional operators to the column name. For example, if the grouping expression is column C1, the select list may contain C1+1.
  • If the grouping expression is not a column name, the select list may not apply additional operators to the expression. For example, if the grouping expression is C1+1, the select list may contain C1+1, but not (C1+1)/8.
• The select list is applied to each group of R, and the result contains as many rows as there are groups in R. When the select list is applied to a group of R, that group is the source of the arguments of the aggregate functions in the select list.
• The RRN, RID, DATAPARTITIONNAME, DATAPARTITIONNUM, DBPARTITIONNAME, DBPARTITIONNUM, and HASHED_VALUE functions cannot be specified in the select list.

If neither GROUP BY nor HAVING is used

• The select list must not include any aggregate functions, or each column-name must be specified in an aggregate function or be a correlated reference.
• If the select list does not include aggregate functions, it is applied to each row of R and the result contains as many rows as there are rows in R.
• If the select list is a list of aggregate functions, R is the source of the arguments of the functions and the result of applying the select list is one row.

In either case the nth column of the result contains the values specified by applying the nth expression in the operational form of the select list.