How to use proper syntax when creating SQL Macro? - macros

Question

Using Oracle SQL Developer, I am trying to make this web (link) example working:
CREATE OR REPLACE FUNCTION concat_self(str VARCHAR2, cnt PLS_INTEGER)
RETURN VARCHAR2 SQL_MACRO(SCALAR)
IS BEGIN RETURN 'rpad(str, cnt * length(str), str)';
END;
/
But I get those errors I do not understand:
Function CONCAT_SELF compiled
LINE/COL ERROR
--------- -------------------------------------------------------------
2/37 PLS-00103: Encountered the symbol "SQL_MACRO" when expecting one of the following: . # % ; is authid as cluster order using external character deterministic parallel_enable pipelined aggregate result_cache accessible
3/4 PLS-00103: Encountered the symbol "BEGIN" when expecting one of the following: not null of nan infinite dangling a empty
5/0 PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following: end not pragma final instantiable order overriding static member constructor map
Errors: check compiler log

Answer 1

Your code is perfectly 'valid' for any instance of Oracle where SQL_MACRO keyword is recognized by the PL/SQL Engine.
The errors start to make a little bit more sense once you realize that the database doesn't understand what you're asking for - it does not recognize that 'SQL_MACRO' is a valid component of the CREATE OR REPLACE FUNCTION PL/SQL library.
Those errors kind of allow you to see how the database's PL/SQL and SQL parser are taking your request and breaking it down into things it knows how to work with.
Everything after the first error is about the parser not being able to make it past the first problem it encountered.
This feature was introduced in version 21c of the database, as explained in the 21c New Features Guide.
You can create SQL Macros (SQM) to factor out common SQL expressions
and statements into reusable, parameterized constructs that can be
used in other SQL statements. SQL macros can either be scalar
expressions, typically used in SELECT lists, WHERE, GROUP BY and
HAVING clauses, to encapsulate calculations and business logic or can
be table expressions, typically used in a FROM clause.
SQL macros increase developer productivity, simplify collaborative
development, and improve code quality.