PHP Script for CRUD Operations using PDO

database.php

<?php

$servername = "your-maria-db-server";
$username = "your-db-username";
$password = "your-db-password";
$dbname = "your-dbanme";

$db = new PDO('mysql:host=' . $servername . ';dbname=' . $dbname, $username, $password);

function selectAnd($entityName, $where = null, $orderBy = null)
{
    global $db;
    $query = 'SELECT * FROM ' . $entityName;
    if ($where != null) {
        if (count($where) > 0) {
            $query .= ' WHERE' . generateWhere('AND', $where);
        }
    }
    if ($orderBy != null) {
        if (count($orderBy) > 0) {
            $query .= ' ORDER BY' . generateOrderBy($orderBy);
        }
    }
    $statement = $db->prepare($query);
    if ($where != null) {
        $statement = bindQuery($statement, $where);
    }
    $statement->execute();
    $result = $statement->fetchAll();
    $statement->closeCursor();
    return $result;
}

function selectOr($entityName, $where = null, $orderBy = null)
{
    global $db;
    $query = 'SELECT * FROM ' . $entityName;
    if ($where != null) {
        if (count($where) > 0) {
            $query .= ' WHERE' . generateWhere('OR', $where);
        }
    }
    if ($orderBy != null) {
        if (count($orderBy) > 0) {
            $query .= ' ORDER BY' . generateOrderBy($orderBy);
        }
        $query = substr($query, 0, intval(strlen($query) - 1));
    }
    $statement = $db->prepare($query);
    if ($where != null) {
        $statement = bindQuery($statement, $where);
    }
    $statement->execute();
    $result = $statement->fetchAll();
    $statement->closeCursor();
    return $result;
}

function insert($entityName, $data)
{
    global $db;
    $query = 'INSERT INTO ' . $entityName . ' ' . generateColumnsParameters('', $data) . ' VALUES ' . generateColumnsParameters(':', $data);
    $statement = $db->prepare($query);
    $statement = bindQuery($statement, $data);
    $statement->execute();
    $statement->closeCursor();
}

function update($entityName, $data, $where)
{
    global $db;
    $query = 'UPDATE ' . $entityName . ' SET ' . generateUpdateParameters($data) . ' WHERE ' . generateWhere('AND', $where);
    $statement = $db->prepare($query);
    $statement = bindQuery($statement, $data);
    $statement = bindQuery($statement, $where);
    $statement->execute();
    $statement->closeCursor();
}

function delete($entityName, $where)
{
    global $db;
    $query = 'DELETE FROM ' . $entityName . ' WHERE ' . generateWhere('AND', $where);
    $statement = $db->prepare($query);
    $statement = bindQuery($statement, $where);
    $statement->execute();
    $statement->closeCursor();
}

function generateWhere($operator, $where)
{
    $query = '';
    foreach ($where as $key => $value) {
        $query .= ' ' . $key . ' = :' . $key . ' ' . $operator;
    }
    $query = substr($query, 0, intval(strlen($query) - intval(strlen($operator) + 1)));
    return $query;
}

function generateOrderBy($orderBy)
{
    $query = '';
    foreach ($orderBy as $value) {
        $query .= ' ' . $value . ',';
    }
    $query = substr($query, 0, intval(strlen($query) - 1));
    return $query;
}

function generateUpdateParameters($data)
{
    $query = '';
    foreach ($data as $key => $value) {
        $query .= $key . ' = :' . $key . ', ';
    }
    $query = substr($query, 0, intval(strlen($query) - 2));
    return $query;
}

function generateColumnsParameters($isParam, $data)
{
    $query = '(';
    foreach ($data as $key => $value) {
        $query .= $isParam . $key . ',';
    }
    $query = substr($query, 0, intval(strlen($query) - 1));
    $query .= ')';
    return $query;
}

function bindQuery($statement, $data)
{
    foreach ($data as $key => $value) {
        $statement->bindValue(':' . $key, $value);
    }
    return $statement;
}