database.class.php

<?php


class DB {

        private static $instance;
        private static $con;
        private static $customError;
        private static $queryObject;

        public static function init($host, $user, $pass, $db) {

            if(!isset(self::$instance)) {

                try {
                    self::$instance = new PDO('mysql:host='.$host.';dbname='.$db, $user, $pass);
                    //self::$instance->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
                    self::$con = true;
                }
                catch (PDOException $e) {

                    self::$customError = $e->getMessage();
                    self::$con = false;
                }
            }
        }

        public static function isConnected() {

            return self::$con;
        }

        public static function select($table, $columns = '*', $where = NULL, $limit = NULL, $column2return = NULL)
        {
            $params = array();
            $sql = "SELECT ";

            if(is_array($columns))
            {
                for($i = 0; $i < count($columns); $i++)
                {
                    $c = $columns[$i];
                    $sql .= "`$c`";

                    if($i != count($columns)-1)
                    {
                        $sql .= ", ";
                    }
                }
            }
            else
            {
                if($columns == '*')
                {
                    $sql .= '*';
                }
                else
                {
                    $sql .= "`$columns`";
                }
            }

            $sql .= " FROM `$table`";

            if($where != NULL)
            {
                //Check if there are WHERE parameters
                if(!is_array($where))
                {
                    echo 'Error in DB::select function: \'where\' parameter must be Array';
                    return false;
                }

                //If WHERE is two values, example: user_id, 1
                //Put them into array for for loop
                if(!is_array($where[0]) && count($where) == 2)
                {
                    $where = array($where);
                }

                $sql .= " WHERE";

                for($i = 0; $i < count($where); $i++)
                {
                    //This current website
                    $w = $where[$i];

                    //Only add if array
                    if(is_array($w))
                    {
                        //column = value
                        //Example: user_id = 19
                        if(count($w) == 2)
                        {
                            $sql .= " `$w[0]` = ?";
                            $params[] = $w[1];
                        }
                        //column operator value
                        //array("user_age", ">", 18)
                        //Example: user_age > 18
                        else if(count($w) == 3)
                        {
                            $sql .= " `$w[0]` $w[1] = ?";
                            $params[] = $w[2];
                        }

                        //If not last item, append "AND" to query
                        if($i != count($where)-1)
                        {
                            $sql = " AND";
                        }
                    }
                }
            }

            if($limit != NULL && is_int($limit))
            {
                $sql .= " LIMIT $limit";
            }

            $results = self::query($sql, $params);

            if(count($results) == 1)
            {
                $results = $results[0];
            }

            if($column2return != NULL)
            {
                if(is_array($column2return))
                {
                    $arr = array();

                    foreach($column2return as $col)
                    {
                        if(isset($results[$col]))
                        {
                            $arr[$col] = $results[$col];
                        }
                    }

                    return $arr;
                }
                else
                {
                    return $results[$column2return];
                }
            }
            else
            {
                return $results;
            }
        }

        public static function query($query, $params = array()) {

            try {
                $params = !is_array($params) ? array($params) : $params;
                $data = array();
                $is_select = strtoupper(substr($query,0,6)) == "SELECT" ? true : false;

                if(count($params) > 0) {

                    $stmt = self::$instance->prepare($query);

                    if(!$stmt)
                    {
                        return false;
                    }

                    $stmt->execute($params);
                    self::$queryObject = $stmt;

                    if($is_select)
                        $data = $stmt->fetchAll(PDO::FETCH_ASSOC);
                    else {
                        $data = true;
                    }

                    $stmt->closeCursor();
                }
                else {

                    $res = self::$instance->query($query);
                    self::$queryObject = $res;

                    if(!$res)
                    {
                        return false;
                    }
                    else if($is_select)
                    {
                        foreach($res as $row)
                            $data[] = $row;
                    }
                    else
                    {
                        $data = true;
                    }
                }

                self::$customError = "";

                return $data;
            }
            catch(Exception $e) {

                self::setError($e->getMessage());
                return false;
            }
        }

        public static function getQueryObj()
        {
            return isset(self::$queryObject) ? self::$queryObject : false;
        }

        public static function getError() {

            if(strlen(self::$customError) > 0)
            {
                return self::$customError;
            }
            else
            {
                $err = self::$instance->errorInfo();
                return $err[count($err)-1];
            }
        }

        public static function setError($e) {

            self::$customError = $e;
        }
    }