Joomla User ID condition for Table and Multi Query

is it possible to set the SQL query condition to = current logged in joomla user?

In other words.

Is it possible to create one table, which will show data that belongs to the current logged in user?

Is it possible to create a table which will display different values extracted from the database?

For example:

Visitors: 340
Users: 2323

I would need to different SQL queries for those two values.

With my first question. I am not sure, if I understood you correct.

With a table I want to write a query like:

$user = Factory::getUser();
$query = "SELECT * FROM table_data WHERE user_id = $user"

This way the table will only show data, that belongs to the current logged in joomla user.

Is this possible???

Really? How we are suppost to handle private user data then?