[sql] How to run SQL in shell script

How do you run a SQL command in a shell script while setting a variable? I had tried this method and it isn't executing the command, it is thinking the command is just a string.

#!/bin/ksh
variable1=`sqlplus -s username/pw@oracle_instance <<EOF
SET PAGESIZE 0 FEEDBACK OFF VERIFY OFF HEADING OFF ECHO OFF
select count(*) from table;
EXIT;
EOF`
if [ -z "$variable1" ]; then
  echo "No rows returned from database"
  exit 0
else
  echo $variable1
fi

sqlplus -s /nolog <<EOF
whenever sqlerror exit sql.sqlcode;
set echo on;
set serveroutput on;

connect <SCHEMA>/<PASS>@<HOST>:<PORT>/<SID>;

truncate table tmp;

exit;
EOF

Maybe it's too late for answering but, there's a working code:

sqlplus -s "/ as sysdba" << EOF
    SET HEADING OFF
    SET FEEDBACK OFF
    SET LINESIZE 3800
    SET TRIMSPOOL ON
    SET TERMOUT OFF
    SET SPACE 0
    SET PAGESIZE 0
    select (select instance_name from v\$instance) as DB_NAME,
           file_name
      from dba_data_files
     order by 2;

You can use a heredoc. e.g. from a prompt:

$ sqlplus -s username/password@oracle_instance <<EOF
set feed off
set pages 0
select count(*) from table;
exit
EOF

so sqlplus will consume everything up to the EOF marker as stdin.

Code

PL_CONNECT_STRING="$DB_USERNAME/$DB_PASSWORD@$DB_SERVICE"

OUTPUT=$(sqlplus -s $PL_CONNECT_STRING <<-END-OF-SQL
           select count(*) from table;
exit;
END-OF-SQL)
echo "COMPLETED GATHER STATS $OUTPUT";

Explanation:

PL_CONNECT_STRING carry database username, password and it service name

sqlplus is used to connect the Database with PL_CONNECT_STRING details

END-OF-SQL tag contain the query which you want to execute

echo is used to print the output of the query

NOTE: You can give multiple Query inside the END-OF-SQL tag, so its useful for batch execution as well