How to replace multiple placeholders in a PHP SQL query

Question

Sorry if the title is strangely worded. This is my first time asking anything here, and I'm pretty new to PHP so I'm having a tough time figuring this out.

Basically, I am trying to write a PHP script that will allow me to change the rules for a certain game instance from our website, so I don't have to go into the database and run a SQL query every time.

This is what I have so far:

public function update_rules() 
    {
        $rules = $this->input->post('rules');
        $domains = $this->input->post('domains_multiselect');

        $qarr = array();
        $sql = "
                    UPDATE domains
                    SET rules = ?
                    WHERE domain_id = ?
                  ";

        $qarr[] = $rules;
        $qarr[] = $domain_id;

        $query = $this->db->query($sql,$qarr);

        redirect ("admin/insert_rules");

    }

I am unsure how to to a substr_replace() to change the "?" placeholders in the query to be able to input both the manually typed rules and the domain_id, which I think will be generated when the domain name is selected.

I could be completely off-base here, but if anyone could point me in some kind of direction, that'd be great. thank you.

It looks like you're working with a PDO prepared statement. You shouldn't do a string replace, but rather a prepare() execute() sequence. Documentation here: php.net/manual/en/pdostatement.execute.php — danielml01
– danielml01, Commented May 13, 2016 at 17:46

K. Bastian · Accepted Answer · 2016-05-13 19:02:57Z

1

you can use either named placeholder or position dependent placeholders...

//Position dependent: 
$stmt = $this->db->prepare("UPDATE domains SET rules = ? WHERE domain_id = ?");
$stmt->bindParam(1, $rules);
$stmt->bindParam(2, $domain_id);
$stmt->execute();

//Named Placeholder: 
$stmt = $this->db->prepare("UPDATE domains SET rules = :rules WHERE domain_id = :domain");
$stmt->bindParam(':rules', $rules);
$stmt->bindParam(':domain', $domain_id);
$stmt->execute();

answered May 13, 2016 at 19:02

K. Bastian

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