Oracle SQL if statement based on parameter passed in via .sh script - sql

Question

I have a shell script which calls some SQL like so
sqlplus system/$password#$instance #./oracle/mysqlfile.sql $var1 $var2 $var3
Then in mysqlfile.sql, I define properties like this:
DEFINE var1=&1
DEFINE var2=&3
DEFINE var3=&3
Later in the file, I call another SQL script:
// i wish to wrap this in a if statement - pseudo-code
if(var3="true") do the following
#./oracle/myOthersqlfile.sql &&varA &&varB
I am not sure how to implement this though, any suggestions appreciated

Answer 1

You could (ab)use substitution variables:
set termout off
column var3_path new_value var3_path
select case
when '&var3' = 'true' then './oracle/myOthersqlfile.sql &&varA &&varB'
else '/dev/null'
end as var3_path
from dual;
set termout on
#&var3_path
The query between the set termout commands - which just hide the output of the query - uses a case expression to pick either your real file path or a dummy file; I've used /dev/null, but you could have a 'no-op' file of your own that does nothing if that's clearer. The query gives the result of that the alias var3_path. The new_value line before it turns that into a substitution variable. The # then expands that variable.
So if var3 is 'true' then that runs:
#./oracle/myOthersqlfile.sql &&varA &&varB
(or, actually, with the varA and varB variables already replaced with their actual values) and if it is false it runs:
#/dev/null
which does nothing, silently.
You can set verify on around that code to see when and where substitution is happening.

Answer 2

You can't implement procedural logic into sqlplus. You have these options :
Implement the IF-THEN-ELSE logic inside the shell script that is running the sqlplus.
Use PL/SQL, but then your SQL Script should be called as a process inside an anonymous block, not like an external script.
In your case the easiest way is to change your shell script.
#/bin/bash
#
# load environment Oracle variables
sqlplus system/$password#$instance #./oracle/mysqlfile.sql $var1 $var2 $var3
# if then
if [ $var3 == "true" ]
then
sqlplus system/$password#$instance #./oracle/myOthersqlfile.sql
fi
You should realise that sqlplus is just a CLI ( Command Line Interface ). So you can't apply procedural logic to it.
I have no idea what you do in those sql scripts ( running DMLs, creating files, etc ), but the best approach would be to convert them to PL/SQL, then you can apply whatever logic you need to.