Login - Code
my $type="mysql";
my $database="database_one";
my $host="localhost";
my $port="3306";
my $user="root";
my $pwd="*****";
my $dsn="dbi:$type:$database:$host:$port";
my $connect=DBI->connect($dsn,$user,$pwd);

>> HTML CODE HERE <<

$query=qq{SELECT * FROM login WHERE username=? AND password=?};
$queryhandle=$connect->prepare($query);
my $login=$queryhandle->execute($param{username},$param{password});
if($login!=0){
 ...
}else{
 ...
}

Post - Code

>>HTML CODE HERE<<
$query=qq{INSERT INTO feed(details,name,date)VALUES(?,?,?)};
$queryhandle=$connect->prepare($query);
$queryhandle->execute("$postparam{details}","$postparam{name}","$postparam{date}");
$queryhandle->finish;

...