Working with functions - Php

Question

I guys, I have a public function user_exists to check if the username already exists on my database table.

public function user_exists($username) {
$query = $this->db->prepare("SELECT COUNT(`id`) FROM `users` WHERE `username`= ?");
$query->bindValue(1, $username);
try{
 $query->execute();
 $rows = $query->fetchColumn();
 if($rows == 1){
 return true;
 }else{
 return false;
 }
} catch (PDOException $e){
 die($e->getMessage());
}
}

And I want to check if the email exists, should I copy paste the user_exists function and just change the function name and the prepare statement like this?

public function email_exists($email) {
$query = $this->db->prepare("SELECT COUNT(`id`) FROM `users` WHERE `email`= ?");
$query->bindValue(1, $email);
try{
 $query->execute();
 $rows = $query->fetchColumn();
 if($rows == 1){
 return true;
 }else{
 return false;
 }
} catch (PDOException $e){
 die($e->getMessage());
}
}

Thanks!

• user1864610: Why don't you try it?
• Lawrence Cherone: or just check_exists($key, $value) use $key for the db column
• Christopher Rioja: I already tried and it is working fine but its a long code. How can I shorten that code? :/
• Funk Forty Niner: You should have posted/stated that --^ in your question then.
• TecBrat: Don't be bashful about trial and error. The industry calls it "iterative testing". If you you are testing and had UPDATE or other write queries, then I'd say just make sure you are operating on test data or that you have a good backup (or both).

Answer 1

You could make a private method that other methods use within the class:

<?php 
/**
 * Presume your user class yada...
 *
 */
class user{
 /**
 * Check email exists
 *
 * @param string $value
 * @return bool
 */
 public function email_exists($value){
 return $this->db_check_exists('email', $value);
 }
 /**
 * Check user exists
 *
 * @param string $value
 * @return bool
 */
 public function user_exists($value){
 return $this->db_check_exists('user', $value);
 }
 /**
 * Private method used by other check methods
 *
 * @param string $column
 * @param string $value
 * @return bool
 */
 private function db_check_exists($column, $value) {
 $query = $this->db->prepare("SELECT 1 FROM `users` WHERE `{$column}` = :value");
 $query->bindValue(':value', $value);
 try{
 $query->execute();
 $rows = $query->fetchColumn();
 if($rows == 1){
 return true;
 }else{
 return false;
 }
 } catch (PDOException $e){
 die($e->getMessage());
 }
 }
}
?>

Answer 2

Combine it into one like this:

public function exists($variable, $statement) {
$query = $this->db->prepare($statement);
$query->bindValue(1, $variable);
try{
$query->execute();
$rows = $query->fetchColumn();
if($rows == 1){
 return true;
}else{
 return false;
}
} catch (PDOException $e){
die($e->getMessage());
}
}

Now $variable is whatever you want to bind, and the $statement is the query statement you want to run. This way means less code to write/decode if theres an error. You just have to pass the information you want into the function

Answer 3

How can I shorten that code?

public function email_exists($email) {
 $stmt = $this->db->prepare("SELECT COUNT(`id`) FROM `users` WHERE `email`= ?");
 $stmt->bindValue(1, $email);
 return ( $stmt->execute()->fetchColumn() == 1 );
}

Answer 4

I could not test this, but try this one:

public function element_exists($element_name,$element_value) {
switch($element_name)
{
 case 'users':
 $safe_element = 'users';
 break;
 case 'email':
 $safe_element = 'email';
 break;
 default:
 return false;
}
$query = $this->db->prepare("SELECT COUNT(`id`) FROM `users` WHERE `$safe_element`= ?");
$query->bindValue(1, $element_value);
try{
 $query->execute();
 $rows = $query->fetchColumn();
 return $rows == 1;
 } 
catch (PDOException $e){
 die($e->getMessage());
 }
}

• TecBrat: Got the idea of the switch statement here: stackoverflow.com/questions/182287
• TecBrat: You asked about shortening the code, and I just noticed the if then else to return a boolean. You can just return the value of the comparison and save the whole if-then-else statement. (see line 24 in my code.)