How to insert php variables into oracle table?

I've got a few php variables that I'd like to insert into an oracle table, but I'm having a hard time with the escape quotes.

Here's what I have so far:

   <?php
     ......
     $number_passed=20;//this is calculated earlier in the code
     $number_total=100;//also calculated earlier in the code
     $date=date('m/d/y');
     $username=//username here
     $password=//password here
     $database=//database connection string here

     $connection=oci_connect($username,$password,$database);

     $sql="INSERT INTO TEST_TABLE (Date_Col,num_pass,num_total) 
               VALUES ('"$date"','"$number_passed"','"$number_total"')";

     $st= oci_parse($$connection, $sql);
     oci_execute($st);

    ?>

When I do this, I get the following error :Parse error: syntax error, unexpected T_VARIABLE on the line where I declare my sql statement. How do I insert the php variables into the database table correctly?

Also, I know I'm supposed to sanitize my php variables before inserting them into the database. Is there a function that does that for me?

Thank you!