Services\ModuleInstaller::alterTables PHP Method

    public function alterTables($form)
    {
        if (isset($this->config['info']['vendor'])) {
            $vendor = Str::lower($this->config['info']['vendor']);
        } else {
            $vendor = '';
        }
        $alter_sql = "ALTER TABLE mdl_{$vendor}_{$form['table']} ";
        $add_columns = array();
        $previous_field = 'id';
        foreach ($form['fields'] as $field) {
            if (!Schema::hasColumn("mdl_{$vendor}_{$form['table']}", $field)) {
                $add_columns[] = "ADD COLUMN `{$field}` text COLLATE utf8_unicode_ci NULL AFTER `{$previous_field}`";
            }
            $previous_field = $field;
        }
        $alter_sql .= implode(', ', $add_columns) . ';';
        DB::unprepared($alter_sql);
    }