PHP PDO MySQL backup script with compression option

Modern PHP PDO MySQL database backup script which includes a gzip compression option.

Modified from this Stack Overflow post, the script is easy to use with configurable options for the directory to save into, file name and date format to append along with the option to compress with gzip.

View script as a Gist.

Full script:

<?php
$backup_config = array(
    'DB_HOST' => '127.0.0.1',////Database hostname
    'DB_NAME' => 'test_db',//Database name to backup
    'DB_USERNAME' => 'root',//Database account username
    'DB_PASSWORD' => '',//Database account password
    'INCLUDE_DROP_TABLE' => false,//Include DROP TABLE IF EXISTS
    'SAVE_DIR' => '',//Folder to save file in
    'SAVE_AS' => 'test_db-',//Prepend filename
    'APPEND_DATE_FORMAT' => 'Y-m-d-H-i',//Append date to file name
    'TIMEZONE' => 'UTC',//Timezone for date format
    'COMPRESS' => true,//Compress into gz otherwise keep as .sql
);

echo backupDB($backup_config);

function backupDB(array $config): string
{
    $db = new PDO("mysql:host={$config['DB_HOST']};dbname={$config['DB_NAME']}; charset=utf8", $config['DB_USERNAME'], $config['DB_PASSWORD']);
    $db->setAttribute(PDO::ATTR_ORACLE_NULLS, PDO::NULL_NATURAL);

    date_default_timezone_set($config['TIMEZONE']);
    $do_compress = $config['COMPRESS'];

    if ($do_compress) {
        $save_string = $config['SAVE_AS'] . $config['SAVE_DIR'] . date($config['APPEND_DATE_FORMAT']) . '.sql.gz';
        $zp = gzopen($save_string, "a9");
    } else {
        $save_string = $config['SAVE_AS'] . $config['SAVE_DIR'] . date($config['APPEND_DATE_FORMAT']) . '.sql';
        $handle = fopen($save_string, 'a+');
    }

    //array of all database field types which just take numbers
    $numtypes = array('tinyint', 'smallint', 'mediumint', 'int', 'bigint', 'float', 'double', 'decimal', 'real');

    $return = "";
    $return .= "CREATE DATABASE `{$config['DB_NAME']}`;\n";
    $return .= "USE `{$config['DB_NAME']}`;\n";

    //get all tables
    $pstm1 = $db->query('SHOW TABLES');
    while ($row = $pstm1->fetch(PDO::FETCH_NUM)) {
        $tables[] = $row[0];
    }

    //cycle through the table(s)
    foreach ($tables as $table) {
        $result = $db->query("SELECT * FROM $table");
        $num_fields = $result->columnCount();
        $num_rows = $result->rowCount();

        if ($config['INCLUDE_DROP_TABLE']) {
            $return .= 'DROP TABLE IF EXISTS `' . $table . '`;';
        }

        //table structure
        $pstm2 = $db->query("SHOW CREATE TABLE $table");
        $row2 = $pstm2->fetch(PDO::FETCH_NUM);
        $ifnotexists = str_replace('CREATE TABLE', 'CREATE TABLE IF NOT EXISTS', $row2[1]);
        $return .= "\n\n" . $ifnotexists . ";\n\n";

        if ($do_compress) {
            gzwrite($zp, $return);
        } else {
            fwrite($handle, $return);
        }
        $return = "";

        //insert values
        if ($num_rows) {
            $return = 'INSERT INTO `' . $table . '` (';
            $pstm3 = $db->query("SHOW COLUMNS FROM $table");
            $count = 0;
            $type = array();

            while ($rows = $pstm3->fetch(PDO::FETCH_NUM)) {
                if (stripos($rows[1], '(')) {
                    $type[$table][] = stristr($rows[1], '(', true);
                } else {
                    $type[$table][] = $rows[1];
                }

                $return .= "`" . $rows[0] . "`";
                $count++;
                if ($count < ($pstm3->rowCount())) {
                    $return .= ", ";
                }
            }

            $return .= ")" . ' VALUES';

            if ($do_compress) {
                gzwrite($zp, $return);
            } else {
                fwrite($handle, $return);
            }
            $return = "";
        }
        $counter = 0;
        while ($row = $result->fetch(PDO::FETCH_NUM)) {
            $return = "\n\t(";

            for ($j = 0; $j < $num_fields; $j++) {

                if (isset($row[$j])) {

                    //if number, take away "". else leave as string
                    if ((in_array($type[$table][$j], $numtypes)) && (!empty($row[$j]))) {
                        $return .= $row[$j];
                    } else {
                        $return .= $db->quote($row[$j]);
                    }
                } else {
                    $return .= 'NULL';
                }
                if ($j < ($num_fields - 1)) {
                    $return .= ',';
                }
            }
            $counter++;
            if ($counter < ($result->rowCount())) {
                $return .= "),";
            } else {
                $return .= ");";
            }
            if ($do_compress) {
                gzwrite($zp, $return);
            } else {
                fwrite($handle, $return);
            }
            $return = "";
        }
        $return = "\n\n-- ------------------------------------------------ \n\n";
        if ($do_compress) {
            gzwrite($zp, $return);
        } else {
            fwrite($handle, $return);
        }
        $return = "";
    }

    $error1 = $pstm2->errorInfo();
    $error2 = $pstm3->errorInfo();
    $error3 = $result->errorInfo();
    echo $error1[2];
    echo $error2[2];
    echo $error3[2];

    if ($do_compress) {
        gzclose($zp);
    } else {
        fclose($handle);
    }
    return "{$config['DB_NAME']} saved as $save_string";
}