Easy to use dynamic SQL table copier

dynTableCopy.php

<?php
// DynTableCopy
// Copyright robske_110 2021

declare(strict_types=1);

$dbConnectionConfig = [
	"DB_SRC_HOST" => null,
	"DB_SRC_NAME" => null,
	"DB_SRC_USER" => null,
	"DB_SRC_PASSWORD" => null,
	"DB_SRC_DRIVER" => null,
	"DB_DEST_HOST" => null,
	"DB_DEST_NAME" => null,
	"DB_DEST_USER" => null,
	"DB_DEST_PASSWORD" => null,
	"DB_DEST_DRIVER" => null,
];

$tableName = null; //ENV is DB_COPY_TABLE
$convertBooleanToInt = null; //ENV is CONVERT_BOOLEAN_TO_INT, set to "no" to disable

// -----

foreach($dbConnectionConfig as $key => $value){
	if($key === null){
		continue;
	}
	$_ENV[$key] = $value;
}
if($tableName !== null){
	$_ENV["DB_COPY_TABLE"] = $tableName;
}
if($tableName !== null){
	$_ENV["CONVERT_BOOLEAN_TO_INT"] = $convertBooleanToInt;
}

$required_envvars = ["DB_SRC_HOST", "DB_SRC_NAME", "DB_SRC_USER", "DB_DEST_HOST", "DB_DEST_NAME", "DB_DEST_USER", "DB_COPY_TABLE"];
foreach($required_envvars as $required_envvar){
	if(!isset($_ENV[$required_envvar])){
		echo("Error: required envvar ".$required_envvar." not set!\n");
		exit;
	}
}

$dbSrc = new DatabaseConnection(
	$_ENV["DB_SRC_HOST"], $_ENV["DB_SRC_NAME"], $_ENV["DB_SRC_USER"], $_ENV["DB_SRC_PASSWORD"] ?? null,
	$_ENV["DB_SRC_DRIVER"] ?? "pgsql"
);
$dbDest = new DatabaseConnection(
	$_ENV["DB_DEST_HOST"], $_ENV["DB_DEST_NAME"], $_ENV["DB_DEST_USER"], $_ENV["DB_DEST_PASSWORD"] ?? null,
	$_ENV["DB_DEST_DRIVER"] ?? "pgsql"
);

$data = $dbSrc->query("SELECT * FROM ".$tableName);
$keys = array_keys($data[0]);

$query = "INSERT INTO ".$tableName."(";
foreach($keys as $key){
	$query .= $key.", ";
}
$query = substr($query, 0, strlen($query)-2);
$query .= ") VALUES(";
for($i = 1; $i < count($keys); ++$i){
	$query .= "?, ";
}
$query .= "?) ";
$query .= QueryCreationHelper::createUpsert($_ENV["DB_DEST_DRIVER"] ?? "pgsql", $keys[0], $keys);
echo("Created insert query ".$query.PHP_EOL);
$insert = $dbDest->prepare($query);

echo("Now INSERTING ".count($data)." row(s)".PHP_EOL);
foreach($data as $row){
	if($_ENV["CONVERT_BOOLEAN_TO_INT"] !== "no"){
		foreach($row as $key => $val){
			if(is_bool($val)){
				$row[$key] = $val ? 1 : 0;
			}
		} 
	}
	$insert->execute(array_values($row));
}

class QueryCreationHelper{
	public static function createUpsert(string $driver, string $primaryKey, array $columns): string{
		switch($driver){
			case "pgsql":
				return self::createPostgresUpsert($primaryKey, $columns);
			default:
				echo("CREATING UPSERT FOR NOT (EXPLICITLY) SUPPORTED DB DRIVER!".PHP_EOL);
			case "mysql":
				return self::createMySQLUpsert($primaryKey, $columns);
		}
	}
	
	public static function createPostgresUpsert(string $primaryKey, array $columns): string{
		$query = "ON CONFLICT (".$primaryKey.") DO UPDATE SET ";
		foreach($columns as $column){
			$query .= $column." = excluded.".$column.", ";
		}
		return substr($query, 0, strlen($query)-2);
	}
	
	public static function createMySQLUpsert(string $primaryKey, array $columns): string{
		$query = "ON DUPLICATE KEY UPDATE ";
		foreach($columns as $column){
			$query .= $column." = VALUES(".$column."), ";
		}
		return substr($query, 0, strlen($query)-2);
	}
}

class DatabaseConnection{
	private PDO $connection;
	
	private string $host;
	private string $db;
	private string $username;
	private ?string $password;
	private string $driver;
	
	public function __construct(string $host, string $db, string $username, ?string $password = null, string $driver = "pgsql"){
		$this->host = $host;
		$this->db = $db;
		$this->username = $username;
		$this->password = $password;
		$this->driver = $driver;
		$this->connect();
	}
	
	public function connect(){
		$this->connection = new PDO(
			$this->driver.":host=".$this->host.";dbname=".$this->db, $this->username, $this->password
		);
	}
	
	public function getConnection(): PDO{
		return $this->connection;
	}
	
	public function query(string $sql): array{
		$res = $this->connection->query($sql);
		return $res->fetchAll(PDO::FETCH_ASSOC);
	}
	
	public function queryStatement(string $sql): PDOStatement{
		return $this->connection->query($sql);
	}
	
	public function prepare(string $sql): PDOStatement{
		return $this->connection->prepare($sql);
	}
}