How to use single quotes inside ssh and sqlplus

Question

Below script helps me to ssh and do sqlplus to fetch info from database. I checked and it worked well but the only problem is if i use single quotes in the sql query then I am getting an error since I already used single quotes for ssh.

db_info=`${ssh_path} -qn ${ssh_host} '
DBHost="<TNS>";
$ORACLE_HOME/bin/sqlplus -s $DBUser/$DBPass@$DBHost <<EOF
set heading off feedback off verify off
Select count(*) from table_name where column = 'hell123';
quit;
EOF
'`
echo $db_info

Answer 1

You can include a ' in a single-quoted string by writing '\'' (explanation).

But it would be easier to use a here document for the shell snippet to run on the remote host.

db_info=$("${ssh_path}" -qn "${ssh_host}" <<\END_SSH
DBHost="<TNS>";
$ORACLE_HOME/bin/sqlplus -s $DBUser/$DBPass@$DBHost <<\END_SQL
set heading off feedback off verify off
Select count(*) from table_name where column = 'hell123';
quit;
END_SQL
END_SSH
)
echo "$db_info"

Answer 2

Thanks Thrig. I used your idea in my script and it works perfectly. Just add '\'' in the place of single quote.

db_info=`${ssh_path} -qn ${ssh_host} '
DBHost="<TNS>";
$ORACLE_HOME/bin/sqlplus -s $DBUser/$DBPass@$DBHost <<EOF
set heading off feedback off verify off
Select count(*) from table_name where column = '\''hell123'\'';
quit;
EOF
'`
echo $db_info