Where its not possible to use a variable (&&var) in SQL*PLUS ?

Question

SQL*Plus Command Reference - DEFINE
Whenever you run a stored query or script, SQL*Plus substitutes the value of variable for each substitution variable referencing variable (in the form &variable or &&variable)
The question is which are the limits of this. Can eg even be between a 'STR&&varING' passed as parameter to some function? Or as parameter I can pass only a single variable and there isnt such auto-casting level ?
I have created DBCA Scripts to batch create a DB. So I want inside these scripts to replace the DBNAME with a variable. So I can create different DBS with these prescriptions from an API tool.
E.g here there are 6 different scenarios where I might need to pass the variable. I dont know
1. On which of the bellow scenarios I can inject the &&var
2. On which I cant and thus have to create a 2nd VAR to inject the 1st one
3. Which dont accept variables at all - but only static text
@D:\app\admin\DBNAMEY\scripts\CreateDB.sql
spool D:\app\admin\DBNAMEY\scripts\CreateDB.log append
startup nomount pfile="D:\app\admin\DBNAMEY\scripts\init.ora";
CREATE DATABASE "DBNAMEY"
DATAFILE 'D:\app\oradata\DBNAMEY\system01.dbf' SIZE ...
GROUP 2 ('D:\app\oradata\DBNAMEY\redo02.log') SIZE 51200K,
I may not start testing the scripts 6 times fearing corrupting my Workstation on half executed scripts.

Answer 1

GoodfireGeorge wrote:
SQL*Plus Command Reference - DEFINE
Whenever you run a stored query or script, SQL*Plus substitutes the value of variable for each substitution variable referencing variable (in the form &variable or &&variable)
The question is which are the limits of this. Can eg even be between a 'STR&&varING' passed as parameter to some function? Or as parameter I can pass only a single variable and there isnt such auto-casting level ?
I have created DBCA Scripts to batch create a DB. So I want inside these scripts to replace the DBNAME with a variable. So I can create different DBS with these prescriptions from an API tool.
E.g here there are 6 different scenarios where I might need to pass the variable. I dont know
1. On which of the bellow scenarios I can inject the &&var
2. On which I cant and thus have to create a 2nd VAR to inject the 1st one
3. Which dont accept variables at all - but only static text
@D:\app\admin\DBNAMEY\scripts\CreateDB.sql
spool D:\app\admin\DBNAMEY\scripts\CreateDB.log append
startup nomount pfile="D:\app\admin\DBNAMEY\scripts\init.ora";
CREATE DATABASE "DBNAMEY"
DATAFILE 'D:\app\oradata\DBNAMEY\system01.dbf' SIZE ...
GROUP 2 ('D:\app\oradata\DBNAMEY\redo02.log') SIZE 51200K,
I may not start testing the scripts 6 times fearing corrupting my Workstation on half executed scripts.
If you can't test because you are afraid the test might fail, you need to address that issue first.  No one on the web is going to give you iron-clad assurance that some code you write is going to work exactly as you expect.
Your script is trying to create a database?  What's the worst thing that can happen if it doesn't work?  Do you know how to manually dis-mantle whatever your script does?  If not, you need to learn.  The knowledge you will gain from that exercise will go a long way to improving your understanding of how these things interrelate.