Question

I have a simple database query I wrapped in my bash script.

In case my query retrieves one row, I want to do several things. If my query retrieves zero rows, I want to terminate my script gracefully.

What is the best way to check if my script retrieves zero rows? Can you please provide some pointers?

Thank you.

Answer 1

Here’s a working bash script to get number of rows from the DB. Just pass the variables and replace FROM part of the sql with yours.

#!/bin/bash
NUMROWS=`$ORACLE_HOME/bin/sqlplus -s $DBUSER/$DBPASSWORDd@//$DBHOST:$DBPORT/$ORACLE_SID   << EOF
WHENEVER SQLERROR EXIT FAILURE ROLLBACK
SET HEADING OFF
SET FEEDBACK OFF
SET PAGES 0
select count(*) from dual;
exit success
EOF`
echo $NUMROWS

HINT:
Replace the last line echo $NUMROWS with exit $NUMROWS and your script will exit gracefully if there are no records. Wrap it in a bash if statement if you want to do other things, as below.

if [ $NUMROWS -lt 1 ]; then
  #exit gracefully
  exit 0; 
fi

# do something