ORDER
Clause (order_clause) 
The ORDER clause (order_clause) specifies a sort sequence for a result table.
Syntax
<order_clause> ::= ORDER BY <sort_spec>,...
<sort_spec> ::=
<unsigned_integer> [ASC |
DESC]
|
<expression> [ASC |
DESC]
Examples
SQL
Tutorial, 
Selecting and
Arranging Rows
Explanation
The sort columns specified in the order clause determine the sequence of the sort criteria.
A number n specified in the sorting specification (sort_spec) identifies the nth column in the result table. n must be less than or equal to the number of columns in the result table.
If a QUERY expression consists of more than one QUERY specification, sort specifications must be specified in one of the following forms.
<sort_spec> ::= <unsigned_integer> [ASC
| DESC]
|
<column_spec> [ASC |
DESC]
As the column specification column_spec in this case, you can either use a reference name reference_name or a column name column_name from the list of selected columns of the first QUERY specification.
Scalable subqueries are not permissible in an ORDER clause.
ASC/DESC
The default setting is ASC.
● ASC: the values are sorted in ascending order.
● DESC: the values are sorted in descending order.
More Information
If a query specification was specified with DISTINCT, the total of the internal lengths of all sorting columns must not exceed 1016 characters; otherwise it can comprise 1020 characters.
Column names in the sort specifications must be columns in the tables of the FROM clause or a result_column_name in the selected columns of the QUERY specification.
If DISTINCT or a set function was used in a selected column, the sort specification must identify a column in the result table.
Values are compared in accordance with the rules for the comparison predicate. For sorting purposes, NULL values are greater than non-NULL values, and special NULL values are greater than non-NULL values but less than NULL values.
See also:
Restrictions for SQL Statements
SELECT Statement (select_statement)