Function _sqlDate

Return the SQL date (Y-m-d) from the given date and format

Package: PHPLucidFrame\Core
Copyright: Copyright (c), PHPLucidFrame.
License: MIT License This source file is subject to the MIT license that is bundled with this source code in the file LICENSE
Author: Sithu sithu@phplucidframe.com
Located at helpers/utility_helper.php

Parameters summary
`string`	`$date`	Date to convert
`string`	`$givenFormat = 'dmy'`	Format for the given date
`string`	`$separator = '-'`	Separator in the date. Default is dash "-"

Return value summary
`string`	the SQL date string if the given date is valid, otherwise null