初学者PHP连接-错误排查

Question

I'm just learning PHP and SQL and need some help. I'm sure it's a very easy fix if you know what you're doing, but I don't yet. There are several similar questions on here already but the weren't able to help me.

I have a splash page I'm creating with 5 fields. I'd like for these fields to be sent to a SQL database on my server after the user hits submit. Here's the pertinent code:

<form action="insert.php" method="post">
First and last name: <input type="text" name="Name"><br>
Email: <input type="text" name="Email"><br>
Debt owed:           <select name="Debt">
  <option>Under $5,000</option>
  <option>$5001-$15,000</option>
  <option>$15,001-$50,000</option>
  <option>$50,000+</option>
</select> <br>
Phone Number ex. (555) 123-4567: <input type"text" name="Number"><br>
State: <select name="State"> 
<option value="" selected="selected">Select a State</option> 
<option value="AL">Alabama</option> 
<option value="WY">Wyoming</option>
</select> (Some opportunities are based on your state)
<input type="submit">
</form>

So it calls insert.php. This is what that file looks like:

<?php
    $con=mysqli_connect("DebtLeads2.db.9463978.hostedresource.com","DebtLeads2", "XXXXXXXXXXXX");
    // Check connection
    if (mysqli_connect_errno())
      {
      echo "Failed to connect to MySQL: " . mysqli_connect_error();

    }

    $sql="INSERT INTO Persons (Name, Email, Debt, Number, State)
    VALUES
    ('$_POST[Name]','$_POST[Email]','$_POST[Debt]','$_POST[Number]','$_POST[State]')";


    if (!mysqli_query($con,$sql))
      {
      die('Error: ' . mysqli_error());
      }
    echo "1 record added";

    mysqli_close($con);
    ?> 

I have successfully created the "Persons" table in SQL with 5 fields. It is connecting to my database. However, I get the following error and I just don't know what to do.

Warning: mysqli_error() expects exactly 1 parameter, 0 given in /home/content/78/9463978/html/MM/gifts/MonetaryMind/insert.php on line 16 Error:

Your guidance would be much appreciated, I'm pulling my hair out over here.

Answer 1

mysqli_error()

should be:

mysqli_error($con);

Also, one of the main advantages of mysqli over mysql is that it has prepared statements, which prevent most SQL-injection problems. You should use them instead of interpolating strings into your queries.

Answer 2

The answer is simple. There is nothing to pull your hair for.

An error message and a manual page are your friends.
You have a message already, says something wrong with the way you are calling mysqli_error() . Well, time for the manual page.

Open your browser, type php.net/ and then the function name. A few keystrokes.

Now a page http://php.net/mysqli_error opened.
There you can read everything you need to know on this function call:

string mysqli_error ( mysqli $link )

link Procedural style only: A link identifier returned by mysqli_connect() or mysqli_init()

Quite simple, eh?