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First of all, your code is vulnerable to SQL Injection. This is a major flaw but thankfully, one that's easily fixed. It is important that you do not leave this open to SQL Injection, even if this is something just for you to use. It'll keep your data safe in the event that someone else manages to access it and also gets you in to good habits.
Secondly, your code isn't working because you haven't specified what columns you want to insert into.
Using your example as a basis, here's a working version.
DO NOT USE THIS, IT IS VULNERABLE CODE
<?php
$link=mysqli_connect("localhost", "root", "");
mysqli_select_db($link, "dataadventurers");
?>
<?php
include "connection.php";
?>
<?php
if(isset($_POST['submit1'])){
$firstname = $_POST['first_name'];
$lastname = $_POST['last_name'];
$middle = $_POST['middle_initial'];
$idnum = $_POST['id_number'];
$email = $_POST['email_add'];
$pass = $_POST['password'];
$bday = $_POST['birthdate'];
$course = $_POST['course'];
$year = $_POST['year'];
//If someone passes 2019'); drop table member_registration; -- for example as the year parameter, MySQL interprets the query string as two separate queries. One to insert a record and the second to drop the table and will execute both
mysqli_query($link, "insert into member_registration (firstname, lastname, middle, idnum, email, pass, bday, course, year) values( '$firstname', '$lastname', '$middle', '$idnum', '$email', '$pass', '$bday', '$course', '$year')");;
}
?>
A MORE SECURE VARIANT
I have a couple of SQL convenience functions based on PDO I use on a regular basis.
They pick up their credentials from an ini file stored outside of the publicly accessible folder structure.
The GetData procedure returns the results in the form of an associative array
UpdateData returns the amount of rows affected.
Ini file example
host=localhost
dbname=dataadventurers
username=user
password=pass
Convenience Functions
/*Put credential ini file path here*/
$credentialFile = "...";
function GetData($sql, $params = null, $paramtypes = null){
//Get database connection details
$credentialsArray = parse_ini_file($credentialFile);
//Create PDO Instance
$db = new PDO('mysql:host='.$credentialsArray['host'].';dbname='.$credentialsArray['dbname'].';charset=utf8mb4', $credentialsArray['username'], $credentialsArray['password'], array(PDO::ATTR_EMULATE_PREPARES => false, PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
if(is_null($params)){ //If no parameters supplied, execute the query as is
$stmt = $db->query($sql);
$results = $stmt->fetchAll(PDO::FETCH_ASSOC);
}
else{
if(count($params) <> count($paramtypes)){ //Check that the parameter count and type count are the same
throw new InvalidArgumentException;
}
$stmt = $db->prepare($sql); //Prepare the statement
for($i=0; $i<count($params); $i++){ //Bind the parameters
$stmt->bindValue($i+1, $params[$i], $paramtypes[$i]);
}
$stmt->execute(); //Execute query
$results = $stmt->fetchAll(PDO::FETCH_ASSOC); //Return the results as an associative array
}
return $results;
}
function UpdateData($sql, $params){
//Get database connection details
$credentialsArray = parse_ini_file($credentialFile);
//Create PDO Instance
$db = new PDO('mysql:host='.$credentialsArray['host'].';dbname='.$credentialsArray['dbname'].';charset=utf8mb4', $credentialsArray['username'], $credentialsArray['password'], array(PDO::ATTR_EMULATE_PREPARES => false, PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
try{
$stmt = $db->prepare($sql); //Prepare the statement
is_null($params){ //If there aren't any parameters to bind...
$stmt->execute(); //...execute statement as is
}
else{
$stmt->execute($params); //otherwise execute with the supplied parameters
}
$results = $stmt->rowCount(); //Return the rowcount
return $results;
}
catch(PDOException $ex){ //Catch any PDO Exceptions
return $ex->getMessage(); //Return the exception message
}
}
Usage
The usage is simple. When selecting data, pass a SQL string, an array containing any parameters and an array containing the parameter types. These arrays must be of the same length.
When updating/inserting/deleting data, pass a SQL string and an array containing the parameters. There is no parameter type requirement for UpdateData.
//GetData with no parameters
$results = GetData('select * from member_registration', [], []);
//GetData with one parameter of type String.
$results2 = GetData('select * from member_registration where firstname = ?', ['David'], [PDO::PARAM_STR]);
//Your insert example
$parameters = [
$firstname,
$lastname,
$middle,
$idnum,
$email,
$pass,
$bday,
$course,
$year
];
$rowsAffected = UpdateData('insert into member_registration (firstname, lastname, middle, idnum, email, pass, bday, course, year) values(?, ?, ?, ?, ?, ?, ?, ?, ?)', $parameters);
Final Thoughts
You'll need to substitute the column names for the fields you have in your database. If any are auto-generated, such as an auto-incrementing ID field, omit that field so it works correctly.
One of your parameters is called $pass. If you're storing passwords in a database, ALWAYS store them in an encrypted form, preferably using bCrypt. This StackOverflow answer explains why/how.
