Raw postfix for where expression

[receiver1]

I think it’s worth adding a postfix (like r(-aw)) that assumes the absence of any operator in WHERE expressions, so that this can be conveniently combined with Medoo::raw. I suggest this because I encountered an IN issue in Medoo described in #1079. As for me, this is a good alternative and a breath of air for complex and large queries

Just for example (let's do without logic):

$database->select('users', ['id', 'name','age'], [
  'id[r]' => Medoo::raw('IN (SELECT `id` FROM `users` WHERE `age` = 5)'),
]

This should generate an SQL query like this:

SELECT `id`, `name`, `age` FROM `users` WHERE `id` IN (SELECT `id` FROM `users` WHERE `age` = 5)

So we don't have an equals operator after id in WHERE.

[catfan]

Thank you for your feedback.

I think I will implement generating subquery in a new way. 🤔