Conditional Exit from the script

Question

Hi,
I have to code the script like the below
--Step 1
begin
If <Table1 doesnot exist> then
Display "User Defined Error Message: Table1 doesnot exit"
EXIT FROM THE SCRIPT(Below sql should not run)
endif
end
--Step 2
spool abc.txt;
select "should not run" from Table1;
spool off;Step 2 should not run if table1 doesnot exist.
Can someone please tell how to conditionally exit the script.
Thanks & Regards,C
CDPrasad
Edited by: cdprasad on Aug 12, 2010 1:35 PM
Edited by: cdprasad on Aug 12, 2010 1:36 PM
Edited by: cdprasad on Aug 12, 2010 1:38 PM
Edited by: cdprasad on Aug 12, 2010 1:38 PM

Answer 1

Hi,
David is right; SQL*Plus is the wrong tool for this job.
If you really want to to this in SQL*Plus, you can achieve a crude type of branching by using sub-sripts. Instead of an IF statement, you use START or @ to run one or another of those sub-scripts, based on a substitution variable, which in turn is set by a query.
For example:
--     abc.sql - Test if table1 exists, and
--                     (1) if it exists, run abc_query.sql to do a query
--                     (2) if it does not exist, run abc_error.sql to display an error message
--     Preliminary query, to define next_script:
COLUMN     next_script_col        NEW_VALUE next_script
SELECT     CASE      COUNT (*)
         WHEN  0  THEN  'abc_error'
                   ELSE  'abc_query'
     END     AS next_script_col
FROM     all_tables
WHERE     table_name     = 'TABLE1'
AND     owner          = 'SCOTT'
--     Now that we know what to do, do it:
@&next_scriptYou would run the above script (abc.sql) and it would decide whether to run the script containing you query, or the script that prints an error message.
Why does table1 sometimes disappear? In a good database design, tables are permanent structures, and get dropped only when they are obsolete. Perhaps you should be TRUNCATing the table, not dropping it.