How to insert a point into PostGIS from PHP?

For the following line, I received an error in my PHP page, but the query is OK when I run it from pgmyadmin.

I am trying to insert a point into my PostGIS from PHP which contains name, address and a geometric point. Here, p_id is primary key and it is an integer.

$sql = "INSERT INTO app (p_id, p_fname, p_lname, p_saddr, p_caddr, the_geom) VALUES(intval($p_id), $fname, $lname, $street, $city, ST_GeomFromText(POINT($long $lat), 4326))";
$result = pg_query($dbh, $sql);

Error:

Warning: pg_query() [function.pg-query]: Query failed: ERROR: syntax error at or near "," LINE 1: ...me, p_saddr, p_caddr, the_geom) VALUES(intval(5), , , , , ST... ^ in /Applications/XAMPP/xamppfiles/htdocs/HostMobileApp/requestProcessor.php on line 66
Error in SQL query: ERROR: syntax error at or near "," LINE 1: ...me, p_saddr, p_caddr, the_geom) VALUES(intval(5), , , , , ST... ^