Incorrect value is inserted in database - php

Question

I have this code:
<form action="#" method="post">
<input type="text" name="famname"/>
<input type="submit" name="submit"/>
</form>
<?php
if(isset($_POST['submit'])){
if(!isset($_POST['famname'])){
echo "Please set Family Name.";
die();
}
$mysqli = new mysqli('localhost', 'root', 'marais19', 'famlink');
if($mysqli->connect_errno) {
echo "Connection Failed (".$mysqli->connect_errno.") : ".$mysqli->connect_error;
die();
}
$e = 'yes';
$stmt = $mysqli->prepare("INSERT INTO families(famname) VALUES (?)");
$stmt->bind_param('d', $e);
$stmt->execute();
}
?>
But if I type Smith into the input box it only puts 0 into the database. The SQL code is as followed:
CREATE TABLE IF NOT EXISTS `families` (
`famname` varchar(30) CHARACTER SET utf8 NOT NULL DEFAULT 'NOFAM',
KEY `famname` (`famname`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
And:
INSERT INTO `families` (`famname`) VALUES
('0');
How can I make it to put Smith into the database and not 0

Answer 1

You are casting it to a number (actually a double) when you bind it to the query. You need to use s instead of d:
$stmt->bind_param('d', $e);
should be
$stmt->bind_param('s', $e);
See the manual on types:
i corresponding variable has type integer
d corresponding variable has type double
s corresponding variable has type string
b corresponding variable is a blob and will be sent in packets