PHP SQL语气中value必须添加单引号

$email='hi@qq.com';

$dbc=mysqli_connect('localhost','root','root','test_store') or die('Error conneting to MySQL server.');
$query="insert into email_list (email) values('$email')";
$result=mysqli_query($dbc,$query) or die('error querying database.');
mysqli_close($dbc);

echo $result.'<br />';
//$result在查询语气后不可打印显示