Querying the moodle database within moodle - php

Question

I am new to moodle. I am trying to query the moodle database using my own PHP scripts. I am using the data manipulation API but i can't seem to fetch anything. What are the steps i should take to accomplish this. I have seen a number of guidelines here and there that I should include the config.php file in moodle so as to access the $DB global variable and hence access the functions of the DML API. The following is my code:
<?php
require '../config.php';
global $DB;
$user= $DB->get_record_sql('SELECT * FROM {mdl_user} WHERE id=?', array(4));
echo mysql_num_rows($user);
?>
I get the following error when I try to run it on TextMate editor:
PHP Warning:  require(../config.php): failed to open stream: No such file or directory in /Applications/MAMP/htdocs/moodle24/sbs_android_app/database_manipulation.php on line 2
PHP Fatal error:  require(): Failed opening required '../config.php' (include_path='.:') in /Applications/MAMP/htdocs/moodle24/sbs_android_app/database_manipulation.php on line 2
I will appreciate the help...Thanks.

Answer 1

This error:
PHP Warning: require(../config.php): failed to open stream: No such file or directory in /Applications/MAMP/htdocs/moodle24/sbs_android_app/database_manipulation.php on line 2
means that the script can't find a file called config.php. ../config.php means the script is going to try and open a file in the script's parent directory called config.php. Be sure your script is actually in that location. If it is not, I recommend changing ../config.php to ./config.php and moving your script into the same directory as config.php.
Because your script can't find config.php, it can't connect to the database (config.php should store the credentials, URL, ect.)

Answer 2

I think you are giving wrong path. please be sure that the path you are giving is correct like
require_once('path_from_rootdir to config.php');
note: path_from_rootdir to config.php is the path to config.php and each directory between the path separated by '/'.

Answer 3

There are two issues with this (as wriiten in the question) four lines code of Moodle-
require '../config.php';
Here code is getting error- "PHP Warning: require(../config.php): failed to open stream" because config.php is being looked into the parent directory & file is not there. Please check the path & put the correct path of config.php.
$user= $DB->get_record_sql('SELECT * FROM {mdl_user} WHERE id=?', array(4));
While working with Moodle DML API, table prefix(by default mdl_) must not be added before the table name within {}. Thus, there must be only {user} in place of {mdl_user}.