PLS-00423

Error: PLS-00423: ORDER BY item must be the number of a SELECT-list expression

Causa: A column alias was used in the ORDER BY clause of a SELECT statement that uses a UNION, INTERSECT, or MINUS set operator. This is not allowed. In such cases, expressions in the ORDER BY clause must be unsigned integers that designate the ordinal positions of select-list items.

Acción: Change the alias in the ORDER BY clause to an unsigned integer that designates the ordinal position of the select item in question.