How to control logic flow in SQL Plus script

Question

Hi
I have the requirement below:
Before I start running an SQL script, I need to ensure that I am connecting as a particular user. If I am not that user, then the script should show a msg "Error - Invalid User - Log in as <<username>>"
Let's say i am executing a script A.sql.
SQL > @<path>a.sql
But before this script is executed -- i shall check for the user:
block begins...
select user into var1 from dual
if upper(var1) != 'ABCUSER' then
-- display the error message and stop execution of this script
else
@<path>a.sql (*it executes what i want :) )
end if;
block ends...
How do I write this code using an SQL script ? Pls sugges

Answer 1

Hi,
As Centinul said, SQL*Plus is poorly equipped to deal with problems like this. If possible, try to do what you want outside of SQL*Plus.
If you really have to do it in SQL*Plus, here are two ideas:
(1) run a script conditionally
(2) deliberately raise an error
(1) Using SQL*Plus substitution variables, you can decide which of several scripts to run as a sub-script, based on the results of some query.
For example, if a.sql is the script that only user ABCUSER is allowed to run, then write two other very short scripts:
(a) warning.sql, such as the following:
--  warning.sql
PROMPT  You are not authorized to do this.
QUIT(b) step_1.sql, which decides whether a.sql or warning.sql should be run, and does it:
--     step_1.sql - Decide whether a.sql or warning.sql is to be run next, and do it.
--     (a) decide:
COLUMN  script_name_col     NEW_VALUE     script_name
SELECT     CASE
          WHEN  USER = 'ABCUSER'
          THEN  'a.sql'
          ELSE  'warning.sql'
     END     AS script_name_col
FROM     dual;
--     do:
@&script_nameYou may want to use @@, or specify a complete path name.
(2) Deliberately raise an error, either in a separate script or in a.sql itself, like this:
WHENEVER     SQLERROR     EXIT
SELECT     CASE
          WHEN  USER = 'ABCUSER'
          THEN  NULL
          ELSE  TO_NUMBER ('This will raise ORA-01722')
     END     AS "Welcome!"
FROM     dual;
WHENEVER     SQLERROR     NONE
-- continue with the original a.sql