Initialize a database connection

[vipsa]

Hi

 

I am new to php

 

I have a small form that collects names and email addresses and inserts it into a database. I have an existing database connection for another form so I want to use that connection so I included the connection file in this script. When I try and insert new content I get errors

( ! ) Warning: mysqli_query() expects parameter 1 to be mysqli, boolean given in C:\wamp\www\headfirst\emailscript\addemail.php on line 14

 

Here is the code

 

<code>

<?php
 

$firstname = $_POST['firstname'];

$lastname = $_POST['lastname'];

$email = $_POST['email'];

 

 

echo "Hi $firstname   $lastname. <br> Thank you for sunmitting the form<br>

we will be sending you an email soon to $email";

 

include  $_SERVER['DOCUMENT_ROOT'] . 'headfirst/includes/db_connection.inc';

 

$sql = "use elvis" . "insert into email_list (first_name, last_name, email)" . "values ('$firstname', '$lastname', '$email')";

mysqli_query($dbconnection, $sql);

mysqli_close($dbconnection);

 

?>

</code>

 

So my question is this: "How do I use an existing connection and how do I initialize it or what do I have to do please?

 

Help is appreciated

 

[vipsa]

My question is also this: "If I closed a database connection how do I open that connection again"

[Ch0cu3r]

So my question is this: "How do I use an existing connection and how do I initialize it or what do I have to do please?

When connecting to MySQL using mysqli you can use either procedural style or object style (read http://us2.php.net/manual/en/mysqli.construct.php). Example proceducal connection

$conn = mysqli_connect('mysql hostname', 'mysql username', 'mysql password', 'msyql database name'); // procedural style connection

 When using procedural msyqli_*() functions, any function that requires the link identifier you pass it usually as the first argument. For example for running a query you'd do   mysqli_query($con, $query). 

 

When I try and insert new content I get errors

( ! ) Warning: mysqli_query() expects parameter 1 to be mysqli, boolean given in C:\wamp\www\headfirst\emailscript\addemail.php on line 14

You get that error when you are not connected to the database. The database connection in db_connection.inc may have failed. Can you post how you are connecting to the database

 

My question is also this: "If I closed a database connection how do I open that connection again"

You reconnect again using mysqli_connect(). But it is recommend to only connect to the database once, rather than connecting/disconnection between queries. Database connections are closed once PHP has finished parsing the code.

 

 

$sql = "use elvis" . "insert into email_list (first_name, last_name, email)" . "values ('$firstname', '$lastname', '$email')";

That will result in an error. You cannot run multiple queries together using mysqli_query(). Is elvis the name of your database? You state which database to use when connecting to the database not in the query.

Edited November 4, 2013 by Ch0cu3r