Beginner's Questions about PHP PEAR DB

Novice asking questions about PHP PEAR DB
Like what

Include "db.php";
$r = Db::connect ("Mysql://root:[email protected]/dbname");
Var_dump ($R);


In the program
Include "db.php";
Does this path need to be changed?

I have installed PEAR DB and Go-pear.phar php-mysql
Still prompt for error db.php not found

If you change the path in the program
No error prompt no output

For advice
How the hell did this get done? and is there any way to say when it's installed?
------Solution--------------------
Well, you didn't install it.
PEAR requires the PEAR installation path to be written in include_path.

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