BASH - Single quote inside double quote for SQL Where clause
Question
I need to send a properly formatted date comparison WHERE clause to a program on the command line in bash.
Once it gets inside the called program, the WHERE clause should be valid for Oracle, and should look exactly like this:
highwater>TO_DATE('11-Sep-2009', 'DD-MON-YYYY')
The date value is in a variable. I've tried a variety of combinations of quotes and backslashes. Rather than confuse the issue and give examples of my mistakes, I'm hoping for a pristine accurate answer unsullied by dreck.
If I were to write it in Perl, the assignment would I think look like this:
$hiwaterval = '11-Sep-2009';
$where = "highwater>TO_DATE(\'$hiwaterval\', \'DD-MON-YYYY\')";
How do I achieve the same effect in bash?
Solution
hiwaterval='11-Sep-2009'
where="highwater > TO_DATE('$hiwaterval', 'DD-MON-YYYY')"
optionally add "export " before final variable setting if it is to be visible ourside the current shell.
OTHER TIPS
Have you tried using using double ticks? Like highwater>TO_DATE(''11-Sep-2009'', ''DD-MON-YYYY''). Just a suggestion. I haven't tried it out.
You can assign the where clause like this:
export WHERECLAUSE=`echo "where highwater >TO_DATE('11-Sep-2009', 'DD-MON-YYYY')"`
(with backticks around the echo statement - they're not showing up in my editor here...)
which works with a shell script of the form:
sqlplus /nolog <<EOS
connect $USERNAME/$PASSWD@$DB
select * from test $WHERECLAUSE
;
exit
EOS