<?php
/**
 * Return a formatted string like vsprintf() with named placeholders.
 *
 * When a placeholder doesn't have a matching key in `$args`,
 *   the placeholder is returned as is to see missing args.
 * @param string $format
 * @param array $args
 * @param string $pattern
 * @return string
 */
function p($format, array $args, $pattern="/\{(\w+)\}/") {
    return preg_replace_callback($pattern, function ($matches) use ($args) {
        return @$args[$matches[1]] ?: $matches[0];
    }, $format);
}

$args = ["database"=>"people", "user"=>"staff", "pass"=>"pass123", "host"=>"localhost"];

// With PHP-like placeholders: the variable is embedded in a string "{$database}" but without the dollar sign
$format = <<<SQL
CREATE DATABASE IF NOT EXISTS {database};
GRANT ALL PRIVILEGES ON {database_name}.* TO '{user}'@'{host}';
SET PASSWORD = PASSWORD('{pass}');
SQL;
echo p($format, $args);
/*
Result:

CREATE DATABASE IF NOT EXISTS people;
GRANT ALL PRIVILEGES ON {database_name}.* TO 'staff'@'localhost';
SET PASSWORD = PASSWORD('pass123');

The `{database_name}` placeholder doesn't exist as a matching key in `$args` so it's returned as is.
*/

// With Ruby-like placeholders
$format = <<<SQL
CREATE DATABASE IF NOT EXISTS :database;
GRANT ALL PRIVILEGES ON :database_name.* TO ':user'@':host';
SET PASSWORD = PASSWORD(':pass');
SQL;
echo p($format, $args, "/:(\w+)/");
/*
Result:

CREATE DATABASE IF NOT EXISTS people;
GRANT ALL PRIVILEGES ON :database_name.* TO 'staff'@'localhost';
SET PASSWORD = PASSWORD('pass123');

The `:database_name` placeholder doesn't exist as a matching key in `$args` so it's returned as is.
*/