A Simple Set of PDO Functions

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Strider64
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I made a series of functions that interact Dynamically with Database Tables and plan on adding more as time goes on. Right now you can Create, Read, Update and Delete and yes it is more suited of Object-oriented Programming, but this is geared more towards beginners in hopes they don't get discourage in PHP programming.

Here's the code.

Code: Select all

<?php

use JetBrains\PhpStorm\Pure;

/*
 * PHP PDO connection
 */
$db_options = array(
    /* important! use actual prepared statements (default: emulate prepared statements) */
    PDO::ATTR_EMULATE_PREPARES => false
    /* throw exceptions on errors (default: stay silent) */
, PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    /* fetch associative arrays (default: mixed arrays)    */
, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
);
$pdo = new PDO('mysql:host=' . DATABASE_HOST . ';dbname=' . DATABASE_NAME . ';charset=utf8', DATABASE_USERNAME, DATABASE_PASSWORD, $db_options);

/*
 * Grab total records (rows) in a database table
 */
function totalRecords($pdo, $table, $page = 'blog') {
    $sql = "SELECT count(id) FROM " . $table . " WHERE page=:page";
    $stmt = $pdo->prepare($sql);

    $stmt->execute([ 'page' => $page ]);
    return $stmt->fetchColumn();

}

/*
 * Fetch Single Record by id
 */
function fetch_by_id($pdo, $table, $id) {
    $sql = "SELECT * FROM " . $table . " WHERE id=:id LIMIT 1";
    $stmt = $pdo->prepare($sql);
    $stmt->execute(['id' => $id]);
    return $stmt->fetch(PDO::FETCH_ASSOC);
}

/*
 * Pagination Format
 * Read all the data from the database table in an array format
 */
function readData($pdo, $table, $page, $perPage, $offset) {
    $sql = 'SELECT * FROM ' . $table . ' WHERE page=:page ORDER BY date_added DESC LIMIT :perPage OFFSET :blogOffset';
    $stmt = $pdo->prepare($sql); // Prepare the query:
    $stmt->execute(['perPage' => $perPage, 'blogOffset' => $offset, 'page' => $page]); // Execute the query with the supplied data:
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
}


/*
 * As long as you have the correct field names as the key and
 * the correct values in the corresponding keys the following
 * procedural function should work with no problem.
 *
 */

/*
 * Insert New Data doing it the procedural way
 */
function insertData(array $data, $pdo, $table) {
    try {
        /* Initialize an array */
        $attribute_pairs = [];

        /*
         * Set up the query using prepared states with the values of the array matching
         * the corresponding keys in the array
         * and the array keys being the prepared named placeholders.
         */
        $sql = 'INSERT INTO ' . $table . ' (' . implode(", ", array_keys($data)) . ')';
        $sql .= ' VALUES ( :' . implode(', :', array_keys($data)) . ')';

        /*
         * Prepare the Database Table:
         */
        $stmt = $pdo->prepare($sql);

        /*
         * Grab the corresponding values in order to
         * insert them into the table when the script
         * is executed.
         */
        foreach ($data as $key => $value)
        {
            if($key === 'id') { continue; } // Don't include the id:
            $attribute_pairs[] = $value; // Assign it to an array:
        }

        return $stmt->execute($attribute_pairs); // Execute and send boolean true:

    } catch (PDOException $e) {

        /*
         * echo "unique index" . $e->errorInfo[1] . "<br>";
         *
         * An error has occurred if the error number is for something that
         * this code is designed to handle, i.e. a duplicate index, handle it
         * by telling the user what was wrong with the data they submitted
         * failure due to a specific error number that can be recovered
         * from by the visitor submitting a different value
         *
         * return false;
         *
         * else the error is for something else, either due to a
         * programming mistake or not validating input data properly,
         * that the visitor cannot do anything about or needs to know about
         *
         * throw $e;
         *
         * re-throw the exception and let the next higher exception
         * handler, php in this case, catch and handle it
         */

        if ($e->errorInfo[1] === 1062) {
            return false;
        }

        throw $e;
    } catch (Exception $e) {
        echo 'Caught exception: ', $e->getMessage(), "\n"; // Not for a production server:
    }

    return true;
}

/*
 * Update data in the procedural way
 */
function updateData(array $data, $pdo, $table): bool
{
    /* Initialize an array */
    $attribute_pairs = [];

    /* Create the prepared statement string */
    foreach ($data as $key => $value)
    {
        if($key === 'id') { continue; } // Don't include the id:
        $attribute_pairs[] = "$key=:$key"; // Assign it to an array:
    }

    /*
     * The sql implodes the prepared statement array in the proper format
     * and updates the correct record by id.
     */
    $sql  = 'UPDATE ' . $table . ' SET ';
    $sql .= implode(", ", $attribute_pairs) . ' WHERE id =:id';

    /* Normally in two lines, but you can daisy-chain pdo method calls */
    $pdo->prepare($sql)->execute($data);

    return true;
}

/*
 * Pagination Links Done Procedurally
 */

function previous_page ($current_page): bool|int
{
    $prev = $current_page - 1;
    return ($prev > 0) ? $prev : false;
}

#[Pure] function previous_link($url="index.php", $current_page)
{
    if(previous_page($current_page) !== false) {
        $links .= '<a href="' . $url . '?page=' . previous_page($current_page) . '">';
        $links .= "&laquo; Previous</a>";
    }
    return $links;
}

function next_page($current_page, $total_pages): bool|int
{
    $next = $current_page + 1;
    return ($next <= $total_pages) ? $next : false;
}

#[Pure] function next_link($url="index.php", $current_page, $total_pages)
{
    if(next_page($current_page, $total_pages) !== false) {
        $links .= '<a href="' . $url . '?page=' . next_page($current_page, $total_pages) . '">';
        $links .= "Next &raquo;</a>";
    }
    return $links;
}

#[Pure] function links_function($url="index.php", $current_page, $total_pages): string
{
    $links .= "<div class=\"pagination\">";
    $links .=previous_link($url, $current_page); // Display previous link if there are any
    if ($current_page <= $total_pages) {
        if ($current_page == 1) {
            $links .= "<a class='selected' href=\"$url?page=1\">1</a>";
        } else {
            $links .= "<a href=\"$url?page=1\">1</a>";
        }

        $i = max(2, $current_page - 5);
        if ($i > 2) {
            $links .= '<span class="three-dots">' . " ... " . '</span>';
        }
        for (; $i < min($current_page + 6, $total_pages); $i++) {
            if ($current_page == $i) {
                $links .= "<a class='selected' href=\"$url?page=$i\">$i</a>";
            } else {
                $links .= "<a href=\"$url?page=$i\">$i</a>";
            }

        }
        if ($i !== $total_pages) {
            $links .= '<span class="three-dots">' . " ... " . '</span>';
        }
        if ($i === $total_pages) {
            $links .= "<a href=\"$url?page=$total_pages\">$total_pages</a>";
        } elseif ($i == $current_page) {
            $links .= "<a class='selected' href=\"$url?page=$total_pages\">$total_pages</a>";
        } else {
            $links .= "<a href=\"$url?page=$total_pages\">$total_pages</a>";
        }

    }
    $links .= next_link('index.php', $current_page, $total_pages); // Display next link if there are any
    $links .= "</div>";
    return $links;
}

/*
     * Delete is probably the easiest of CRUD (Create Read Update Delete),
     * but is the most dangerous method of the four as the erasure of the data is permanent of
     * PlEASE USE WITH CAUTION! (I use a small javascript code to warn users of deletion)
     */
function delete($id, $table, $pdo): bool
{
    $sql = 'DELETE FROM ' . $table . ' WHERE id=:id';
    return $pdo->prepare($sql)->execute([':id' => $id]);
}

function logout() {
    unset($_SESSION['last_login'], $_SESSION['id']);
    header("Location: index.php");
    exit();
}

I am currently developing a website in order to help beginners in PHP Programming and Vanilla Javascript for those that don't want to do frameworks.
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