PHP - 具有SQL查询的多个函数

Question

So I have a PHP file with multiple functions that do different queries, example:

function getUserEmail($name)
{
    $link=getLink();
    $name=mysqli_real_escape_string($link, $name);
    $output=mysqli_fetch_array(mysqli_query($link, "SELECT email FROM users WHERE name='$name';"));
    mysqli_close($link);
    return $output[0];
}

function getUserName($id)
{
    $link=getLink();
    $id=mysqli_real_escape_string($link, $id);
    $output=mysqli_fetch_array(mysqli_query($link, "SELECT name FROM users WHERE id='$id';"));
    mysqli_close($link);
    return $output[0];
}

function getLink()
{
    $link = mysqli_connect('localhost', 'myUser', 'myPass');
    mysqli_select_db($link, 'myDB');
    if (!$link) die(mysqli_error($link));
    return $link;
}

(this code might not work, it's just an example)

I have it done similar to the example above, but I think because of the many functions being called on a page reload, the multiple DB link creation and closure is not the most efficient way to proceed (and is starting to lag because of the multiple features added to my project).

Ny thought was: creating the $link to the DB on the header of the PHP and saving it to a $_POST var (like $_POST['link']) and then using it through the code, and closing it on the footer.

This would prevent multiple link creations and closures, and I think would improve performance.

Any thoughts?

Answer 1

If these functions are part of a class

you can include the __construct() and '__destruct()` functions where you deal with database connection. For example:

<?php
  class account {
    protected $link;

    function __construct() {
      $link=getLink();
    }

    function __destruct() {
      mysqli_close($link);
    }

    function getUserEmail($name)
    {
      $name=mysqli_real_escape_string($link, $name);
      $output=mysqli_fetch_array(mysqli_query($link, "SELECT email FROM users WHERE name='$name';"));
      return $output[0];
    }

    function getUserName($id)
    {
      $id=mysqli_real_escape_string($link, $id);
      $output=mysqli_fetch_array(mysqli_query($link, "SELECT name FROM users WHERE id='$id';"));
      return $output[0];
    }

    function getLink()
    {
      $link = mysqli_connect('localhost', 'myUser', 'myPass');
      mysqli_select_db($link, 'myDB');
      if (!$link) die(mysqli_error($link));
      return $link;
    }
  }

That way you don't have to worry about reopening the connection and closing it. The connection automatically opens when the account object is created and it automatically closes when the account object is no longer being referenced.

Read more about constructors and destructors here .

Additionally, as suggested in the comments, you could include a broad getUser() method so that you wouldn't have to query the database for all of the user's separate entries. It would elliminate the amount of times you interacted with the database and would be a more efficient way to deal with the data. Like so:

function getUser($id)
{
  $id=mysqli_real_escape_string($link, $id);
  $output=mysqli_fetch_array(mysqli_query($link, "SELECT * FROM users WHERE id='$id';"));
  return $output;
}

Answer 2

Use a global

$link=false;
function getLink()
    {
      global $link;
      if (!$link) {
      $link = mysqli_connect('localhost', 'myUser', 'myPass');
      mysqli_select_db($link, 'myDB');
      if (!$link) die(mysqli_error($link));
      }
      return $link;
    }

This way, the first call to getLink() establishes a connection, and all subsequent calls simply re-use the connection established by the first call. After making this change, you can keep the rest of your code the same. Being able to use OOP I think is actually a great benefit of using mysqli over mysql , but if you don't want to use OOP this should do it for you.