validating against duplicate db entries

[Anon]

Hi there,
I am doing a rates management part of a guesthouse reservations system and I am trying to add,edit and delete rates.When I add a new rate I want to make sure that the rate name does not already exist in the database and alert back to the user if it does. Also I want to make sure that the dates I am entering do not overlap with any dates already in the db.
I am stuck on this so any suggestions would be greatly appreciated.

-Jenny

[Anon]

Hi Jenny,

One way you could accomplish this is to do a query and query against the database field that you do not want to have a duplicate of. If the query returns no results then do the insert query and if the query returns a result don't do the insert query and show the error page. The code to do this using MySql would be:

$result = mysql_query("SELECT column_name FROM tablename WHERE field_to_be_checked = $value_to_be_checked_for",$link_name);

if (mysql_num_rows($result) >= 1) {
echo(" Your error message here ");
} else {
$insert = mysql_query("INSERT INTO tablename (field_1,field2) VALUES ($field_1_value,$field_2_value)",$link_name);
}

replace the $link_name with the name of the link to the database and the field names with the names for your fields. This will work for both checks.

Hope this helps