You could use conditional compilation, based on dbms_db_version values:
declare
$if not dbms_db_version.ver_le_11_2 $then
l_var number;
$end
begin
$if dbms_db_version.ver_le_11_2 $then
null;
$else
select json_value('{x:42}', '$.x') into l_var from dual;
dbms_output.put_line('12c+: ' || l_var);
$end
end;
/
On 11gR2 this just gets:
PL/SQL procedure successfully completed.
On 12c it gets:
12c+: 42
PL/SQL procedure successfully completed.
Wrap any variable declarations that are only relevant to 12c+ operations, and any code that you only want to call in 12c and above, in conditions.
Of course, this will only work on version 11gR2 or above; if you need to be able to run (without doing anything) on 11gR1 then change the check to ver_le_11. Even that won't be recognised if you try to run on a 10g or earlier database though.
If you need to handle other earlier versions, you can check the version number directly (as @Wernfried showed):
declare
$if dbms_db_version.version >= 12 $then
l_var number;
$end
begin
$if dbms_db_version.version >= 12 $then
select json_value('{x:42}', '$.x') into l_var from dual;
dbms_output.put_line('12c+: ' || l_var);
$else
null;
$end
end;
/
The $else null; part is only needed because I have nothing else in my block - I would get PLS-00103: Encountered the symbol "END" ... without it (in 11g or earlier). If there is other unconditional code then that isn't necessary, though it may still be clearer to include it.
