[RESOLVED] How to check if entry already exists in MySQL table

[chrisdee]

Hello. I have the following script that adds data to a mysql table :

<?php
#connects to the MySQL server
$username = "my_username";
$password  = "my_password";
$host         = "localhost";
$database  = "my_database";
$table        = "my_table";

mysql_connect($host,$username,$password) or die(mysql_error());
mysql_select_db($database) or die(mysql_error());

$id=$_GET['id'];
$category=escapeshellcmd($_POST['category']);

$query = mysql_query("SELECT category FROM $table WHERE category=$category");
$check = mysql_fetch_array($query);

if(!$_POST) {
 echo "<form method='post' action='add.php'>";
 echo "Category :<br><input type=='text' size='64' name='category'<br>";
 echo "<input type='submit' value='Add'>";
 echo "<input type='button' onclick='history.go(-1)' value='Cancel'>";
 echo "</form>";
}

elseif ($query==$category) {
 echo "<a href='#' onclick='history.go(-1)'>Duplicate entry not allowed!</a><br>";
}

else {
 $insert = "INSERT INTO $table SET category='$category'";
 $query = mysql_query($insert) or die(mysql_error());
 echo "Post added<br>";
 echo "<br><a href='admin.php'>To mainpage</a>";
}
?>

I'm trying to get my script to check wether the category name already exist or not in the table. If the name already exists I want the script to choose another name because duplicate entry is not allowed. But I can't get it to work. Any suggestions are greatly apreciated ?

[djjjozsi]

set a unique settings in your table for that field,

<?php

$insert = sprintf( "INSERT INTO %s SET category='%s'" , $table , mysql_real_escape_string( $category ) );
$query = mysql_query( $insert );

if ( $query == true )
    print "New categrory added";
else {
    if ( mysql_errno() == 1062 ) // if this error number is the duplicate error, handle it.
        print "This category is aready in the table!";
    else
        die( "Error in this query: " . mysql_error() . " " . $insert );
} 

?>

[chrisdee]

Thanks for answer. I actually found the solution below my self based on your help.

else {
 $insert = "INSERT INTO $table SET category='$category'";
 $query = mysql_query($insert) or die("<a href='#' onclick='history.go(-1)'>Duplicate entry not allowed!</a><br>");
 echo "Post <font color=green>$category</font> added<br>";
 echo "<br><a href='admin.php'>To mainpage</a>";
}

Thanks for guiding me in the right direction🙂

[djjjozsi]

Your welcome.

Don'T forget to set this thread as resolved.

hello, jjozsi