Sådan skriver du mysql-forespørgsel for at kontrollere flere variabelvalg, hvor formularindsendelse kan matche 1 0f 5 felter

Jeg personligt er ikke særlig god til at lave MySQL-forespørgselsstrenge, jeg bruger generelt en sql-compilerklasse, der ligner denne (husk på, at dette kun er en hurtig en). Det giver mulighed for binding, som du har brug for, især med $_GET værdier, som du har:

class ItemQueue
    {
        protected   $sql;
        protected   $wherevals;
        public      $bind;
        public      $compiled;

        public function select($values = false)
            {
                $this->sql[] = "select";
                if($values == false)
                    $this->sql[]    =   "*";
                else
                    $this->sql[]    =   $values;

                return $this;
            }

        public function from($table = false)
            {
                if($table ==false)
                    return $this;

                $this->sql[] = "from `$table`";

                return $this;
            }

         public function where($values = array(),$op = 'and')
            {
                if(!empty($values)) {
                        $this->sql[]    =   'where';
                        foreach($values as $key => $values) {
                                $this->wherevals[]      =   $key.' = :'.$key;
                                // Bind values for injection protection
                                $this->bind[":$key"]    =   $values;
                            }

                        $this->sql[]        =   implode(" $op ",$this->wherevals);
                        // This part is a bit jenky but you get the idea
                        $this->sql[]        =   "and active = '1'";
                    }

                return $this;
            }

        public  function customsql($values = false)
            {
                if($values != false) {
                        $this->sql[]    =   $values;
                    }

                return $this;
            }

        public  function Fetch()
            {
                // Implode entire sql statement
                $this->compiled =   implode(" ", $this->sql);

                return $this;
            }
    }

    // Post/Get values
    $_POST['cat']   =   'cattest';
    $_POST['city']  =   'Reno';
    $_POST['state'] =   'Nevada';

    // Arbitrary limits
    $limit          =   1;
    $limitvalue     =   1;
    // Create instance
    $tester =   new ItemQueue();
    // Just set some array filtering/validating
    if(isset($_POST['cat']) && !empty($_POST['cat']))
        $array['cat']   =   $_POST['cat'];

    if(isset($_POST['city']) && !empty($_POST['city']))
        $array['city']  =   $_POST['city'];

    if(isset($_POST['state']) && !empty($_POST['state']))
        $array['state'] =   $_POST['state'];

    // Make the query
    $query  =   $tester->select()->from("items")->where($array,"or")->customsql("ORDER BY item_id DESC LIMIT $limitvalue, $limit");

    // Here is the sql statement
    echo $query->Fetch()->compiled;

    // Bind array
    print_r($query->bind);

Giver dig:

select * from `items` where cat = :cat or city = :city or state = :state and active = '1' ORDER BY item_id DESC LIMIT 1, 1

Array
    (
        [:cat] => cattest
        [:city] => Reno
        [:state] => Nevada
    )

Bemærk, dette kræver, at du bruger en korrekt forbindelse (PDO fungerer bedst i dette tilfælde).