Perl CGI无法正确运行sql

Question

我正在基本注册页面上工作，但似乎无法获取用户名检查来触发或实际插入数据库。在此页面中，我将获取从html页面传入的信息，然后首先检查用户名是否已存在。如果没有，我重定向。否则，我将这些值插入db并重定向到新页面。我得到的输出是这样的：

我无法找到代码中的实际问题。

    #!/usr/bin/perl 
#This is going to be the user login check and will set a cookie

use DBI;
use CGI qw(:standard);
print "Content-type: text/html\n\n"; #Tells website to print content

use strict;

#Connection error 
sub showErrorMsgAndExit {
    print header(), start_html(-title=>shift);
    print (shift);
    print end_html();
    exit;
}

#Connecting to the database
my $dbUsername = "root";
my $dbPassword = "password";

my $dsn = "DBI:mysql:f18final:localhost";
my $dbh = DBI->connect($dsn, $dbUsername, $dbPassword, {PrintError => 0});

#error checking
if(!$dbh) {
    print header(), start_html(-title=>"Error connecting to DB");
    print ("Unable to connec to the database");
    print end_html();
    exit;
}


print header;
print start_html(-title=>'Registration Page');

#Get the information the user entered
my $username = param('username');
my $password = param('password');
my $name = param('name');

#first sql check to see if username is already taken
my $check = "SELECT * from tblusers WHERE login = $username";
my $sth = $dbh->prepare($check);
$sth->execute();
if($sth->fetchrow_array) {
    print "<p>The user already exists. You will be redirected to register page in 5 seconds.</p>";
    print qq{<meta http-equiv="refresh" content = "5; url=/var/www/html/register.html"};
} else {
    #prepare to enter the content into the db
    my $sql  = "INSERT INTO tblusers(login, password, name) VALUES($username, $password, $name)";
    my $sth = $dbh->prepare($sql);
    $sth->execute();
    print "<p>Successfuly registered. You will be redirected to login in 5 seconds.</p>";
    print qq{<meta http-equiv="refresh" content = "5; url=/var/www/html/login.html"};
}


print end_html();
exit;

编辑：该帖子的更多详细信息 我在register.cgi上运行chmod，并在perl register.cgi上运行，这就是输出。 html文件仅包含以下形式：

我的sql表如下所示。 （我在mysql工作台中手动添加了第一个帐户）

Answer 1

只需在一个答案中总结池上的评论...

您的SQL查询中有错误。字符串变量在查询中传递时需要加引号。这将在数​​据库中生成一个错误，但是您将看不到它，因为您没有在句柄上设置RaiseError属性，并在其上禁用了PrintError。

在连接数据库时启用错误管理：

my $dbh = DBI->connect($dsn, $dbUsername, $dbPassword, {RaiseError => 1});

为避免引用问题，同时保护您的代码免遭SQL注入，请使用绑定参数。

查找用户时：

my $check = "SELECT * from tblusers WHERE login = ?";
my $sth = $dbh->prepare($check);
$sth->execute($username);

创建新用户时：

my $sql  = "INSERT INTO tblusers(login, password, name) VALUES(?, ?, ?)";
my $sth = $dbh->prepare($sql);
$sth->execute($username, $password, $name);