Refreshing Page

Hi
Have the code below

It checks for

Empty fields
if it is then error

checks for numbers when it should be strings and vice versa

however i do not know how to do it so if the user enters numbers and strings i.e ghf65 then it produces an error.

//If User has entered characters instead of nuumbers and then will cause an error
if(ereg("^[a-zA-Z]$*", $_POST['option'])) echo 'needs to be numba';

//If User has entered nothing, then it will cause an error
else if (empty($_POST['option']))

ps
if you think coding is inconsistent please advise me, i would welcome and suggestions

also how do i do it so if the user presses the back button, the previous version of the database is not seen. i.e. the rows before delete

Cheers

<?php

$listCurrentRecords=true;

if (isset($_POST['s'])) {
$listCurrentRecords=false;
$matchingRecords=true;
}

if($listCurrentRecords) {

echo ( '<form action="shoppingDatabaseDelete.php" method="post">' );

//Connection to Database
$dbcon=pg_pconnect("host=dbh port= dbname=uc user=c password=ect");

//SQL statement looking for information in the database
$sql="SELECT * FROM shop";

//Prints the SQL statement
echo $sql;

//Stores the result of the SQL statement
$result = pg_exec($sql);

//Returns the number of rows in the result
$nrows = pg_numrows($result);