无法连接到数据库？

Question

This is my php code below. For some reason, when I want it to connect to the database, it says "No database selected" but when I do a connection test it says "Success in database connection!" So there's an error in the code below. Also I think it may be interfering with my form so I must have a typo; when I remove the PHP the forms runs normally, but I want it to connect to the database.

<?php
// let's initialize vars to be printed to page in the HTML section so our script does not return errors 
// they must be initialized in some server environments, not shown in video
$errorMsg = "";
$First_Name = "";
$Last_Name = "";
$Email = "";
$Password = "";


// This code runs only if the form submit button is pressed
if (isset ($_POST['firstname'])){

    /* Example of cleaning variables in a loop
    $vars = "";
    foreach ($_POST as $key => $value) {
       $value = stripslashes($value);
       $vars .= "$key = $value<br />";
    }
    print "$vars";
    exit();
    */
     $First_Name = $_POST['firstname'];
     $Last_Name = $_POST['lastname'];
     $Email = $_POST['email'];
     $Password = $_POST['password'];

     // Connect to database
     include "connect_to_mysql.php";
     $emailCHecker = mysql_real_escape_string($Email);
     $emailCHecker = eregi_replace("`", "", $EmailCHecker);
     // Database duplicate e-mail check setup for use below in the error handling if else conditionals
     $sql_email_check = mysql_query("SELECT email FROM members WHERE email='$emailCHecker'");
     $email_check = mysql_num_rows($sql_email_check); 

}

     $sql = mysql_query("INSERT INTO members (firstname, lastname, email, password, sign_up_date) 
     VALUES('$First_Name','$Last_Name','$Email','$Password', now())")  
     or die (mysql_error());

     $id = mysql_insert_id();

     // Create directory(folder) to hold each user's files(pics, MP3s, etc.)        
     mkdir("members/$id", 0755);    

?>

This is my form coding below

    <form action="index.php" method="post" enctype="multipart/form-data">
  <tr>
    <td width="23%" class="right">First Name:</td>
    <td width="77%" class="left left_nowrap"><input type="text" class="left left_nowrap tb10" id="First_Name" value="<?php print "$First_Name"; ?>"/></td>
  </tr>
  <tr>
    <td class="right">Last Name:</td>
    <td class="left left_nowrap"><input type="text" class="left left_nowrap tb10" id="Last_Name"  value="<?php print "$Last_Name"; ?>" />
    </td>
  </tr>
  <tr>
    <td class="right">Email:</td>
    <td class="left left_nowrap"><input type="text" class="left left_nowrap tb10" id="Email" value="<?php print "$Email";?>" /></td>
  </tr>
  <tr>
    <td class="right">Password:</td>
    <td class="left left_nowrap"><input type="password" class="left left_nowrap tb10" id="Password"/></td>
  </tr>
  <tr>
    <td class="right">Confirm Password:</td>
    <td class="left left_nowrap"><input type="password" class="left left_nowrap tb10" id="Confirm_Password"/></td>
  </tr>
  <tr>
    <td class="right">Gender:</td>
    <td class="left left_nowrap"><span class="right">
      <select name="Gender" class="large tb10" id="Gender" value="<?php print "$gender"; ?>">
        <option value="Please Select...">Please Select...</option>
        <option value="Male">Male</option>
        <option value="Female">Female</option>
      </select>
    </span></td>
  </tr>
  <tr>
    <td class="right">&nbsp;</td>
    <td class="left"><input type="submit" class="submit tb10" value="Sign-UP" /></td>
  </tr>     
    </form>

connect_to_mysql.php

 <?php 

/* 
1: "die()" will exit the script and show an error statement if something goes wrong with the "connect" or "select" functions. 
2: A "mysql_connect()" error usually means your username/password are wrong 
3: A "mysql_select_db()" error usually means the database does not exist.
*/
// Place db host name. Sometimes "localhost" but 
// sometimes looks like this: >>      ???mysql??.someserver.net
$db_host = "localhost";
// Place the username for the MySQL database here
$db_username = "Shayaa"; 
// Place the password for the MySQL database here
$db_pass = "nestle324"; 
// Place the name for the MySQL database here
$db_name = "social_media";

// Run the actual connection here 
$con = mysql_connect("$db_host","$db_username","$db_pass") or die ("could not connect to mysql");
mysql_select_db('social_media', $con ) or die ("no database");         
?>

Answer 1

MySQL server can handle many databases. At a minimum you'll have the mysql database itself, which holds server specific data like user accounts and your own application database.

So simply connecting to the server is not enough for any query related to a database. You have to select a database.

in your case, without modifying the rest of the code and MySQL API you need to utilize this command before you can submit a query

mysql_select_db( 'your database name', $dbConnection );

http://php.net/manual/en/function.mysql-select-db.php

Using PHP's MySQL extension is not recommended, since this is going to be removed in future PHP versions. See the link above for alternatives

Answer 2

• use mysqli or PDO

• look if you are selecting databse while you are getting no database selected $sql = mysql_select_db('your database name', $connection)

• stristr achieves exactly the same result as eregi_replace (at least when you don't use regular expressions):

EDIT:

         $sql= "INSERT INTO members (firstname, lastname, email, password,bio_body, sign_up_date , account_type) 
 VALUES(  '".$_SESSION['firstname']."','".$_SESSION['lastname']."','".$_SESSION['email']."','".$_SESSION['password']."','NULL' ,NOW() , 'a' ) " ; 

 if (!mysql_query($sql))
{
 die('Error: ' . mysql_error());
}
echo "1 record added";