Tidbits

    # Put SQL output into shell variable
    nextday=`sqlplus -s <<! # backquotes better
    define dt = $somedate
    define fmt = yyyy-mm-dd
    select
      to_char(to_date('&dt','&fmt')+1,'&fmt')
    from dual;
    !
    `

    # myshellscript mysqlscript.sql $var1 $var2
    sqlplus -s <<!  # do whatever script I say...
    @$*
    !
    
    # echo 'select * from mytable;'|myshellscript
    sqlplus -s <<!  # do whatever I say ...
    $(cat -)
    !

    # Send SQL output through shell pipe
    sqlplus -s <<! |
    -- whatever sql here
    !
    while read line; do whatever with $line; done