I'm new to this and I know I'm probably doing this entire thing the wrong way, but I've been at it all day trying to figure it out. I'm realizing there's a big difference between programming a real project of my own rather than just practicing small syntax-code online. So, I lack the experience on how to merge/pass different variables/scopes together. Understanding how to fit everything within the bigger picture is a completely different story for me. Thanks in advance.
What I'm trying to do, is to make the function "selectyacht" output data in a different location from where it's being called (in viewship.php). The output data (in viewship.php) needs to be only certain fields (not everything) returned and those results will be scattered all over the html page (not in a table). In addition to that, I have this variable: "$sqlstatement" (in sqlconn.php) that I'm trying to bring outside the function because I don't want to repeat the connection function every time. I tried a global variable, as much as I shouldn't, and it thankfully it gave me an error, which means I have to find a better way.
Basically my struggle is in understanding how I should structure this entire thing based on two factors:
This is probably very simple, but yet it eludes me. P.S. Some of this code is a copy/paste from other resources on the internet that I'm trying to merge with my own needs.
sqlconn.php
<?php
$servername = "XXXXXXXX";
$username = "XXXXXXXX";
$password = "XXXXXXXX";
$dbname = "XXXXXXXX";
// Instantiate the connection object
$dbconn = new mysqli($servername, $username, $password, $dbname);
// Check if the connection works or show an error
if ($dbconn->connect_error) {
die("Connection failed: " . $dbconn->connect_error);
}
// Create a query based on the ship's name
function selectyacht($shipname) {
global $sqlstatement;
$sqlstatement = "SELECT * FROM ships WHERE Name=" . "'" . $shipname . "'";
}
// Put the sql statement inside the connection.
// Additional sql statements will be added in the future somehow from other functions
$query = $dbconn->query($sqlstatement);
// Return the data from the ship to be repeated as less as possible for each future function
if ($query->field_count > 0) {
while($data = $query->fetch_assoc()) {
return $data;
}
}
else {
echo "No data found";
}
// Close the connection
$dbconn->close();
?>
viewship.php
<html>
<body>
<?php include 'sqlconn.php';?>
<!-- ship being selected from different buttons -->
<?php selectyacht("Pelorus");?>
<br>
<!-- This is the output result -->
<?php echo $data["Designer"];?>
<?php echo $data["Length"];?>
<?php echo $data["Beam"];?>
<?php echo $data["Height"];?>
</body>
</html>
Mate, I am not sure if I can cover whole PHP coding standards in one answer but I will try to at least direct you.
First of all you need to learn about classes and object oriented programming. The subject itself could be a book but what you should research is autoloading which basically allows you to put your functions code in different files and let server to include these files when you call function used in one of these files. This way you will be able to split code responsible for database connection and for performing data operations (fetching/updating/deleting).
Second, drop mysqli and move to PDO (or even better to DBAL when you discover what Composer is). I know that Internet is full of examples based on mysqli but this method is just on it's way out and it is not coming back.
Next, use prepared statements - it's a security thing (read about SQL injection). Never, ever put external variables into query like this:
"SELECT * FROM ships WHERE Name=" . "'" . $shipname . "'";
Anyone with mean intentions is able to put there string which will modify your query to do whatever he wants eg. erase your database completely. Using prepared statements in PDO your query would look like this:
$stmt = $this->pdo->prepare("SELECT * FROM ships WHERE Name = :ship_name");
$stmt->bindValue(':ship_name', $shipname);
Now to your structure - you should have DB class responsible only for database connection and Ships class where you would have your functions responsible eg. for fetching data. Than you would pass (inject) database connection as an argument to class containing you selectYacht function.
Look here for details how implementation looks like: Singleton alternative for PHP PDO
For
'Returning data in a different place from where it's being called'
If I understand you correctly you would like to have some field to input ship name and button to show its details after clicking into it. You have 2 options here:
standard form - you just create standard html form and submit it with button click redirecting it to itself (or other page). In file where you would like to show results you just use function selectYacht getting ship name from POST and passing it to function selectYacht and then just printing it's results (field by field in places you need them)
AJAX form - if you prefer doing it without reloading original page - sending field value representing ship name via AJAX to other page where you use selectYacht function and update page with Java Script