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<?php
/**
* Elgg database
* Contains database connection and transfer functionality
*
* @package Elgg
* @subpackage Core
* @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
* @author Curverider Ltd
* @copyright Curverider Ltd 2008
* @link http://elgg.org/
*/
/**
* Connect to the database server and use the Elgg database for a particular database link
*
* @param string $dblinkname Default "readwrite"; you can change this to set up additional global database links, eg "read" and "write"
*/
function establish_db_link($dblinkname = "readwrite") {
// Get configuration, and globalise database link
global $CONFIG, $dblink;
if (!isset($dblink)) {
$dblink = array();
}
if ($dblinkname != "readwrite" && isset($CONFIG->db[$dblinkname])) {
if (is_array($CONFIG->db[$dblinkname])) {
$index = rand(0,sizeof($CONFIG->db[$dblinkname]));
$dbhost = $CONFIG->db[$dblinkname][$index]->dbhost;
$dbuser = $CONFIG->db[$dblinkname][$index]->dbuser;
$dbpass = $CONFIG->db[$dblinkname][$index]->dbpass;
$dbname = $CONFIG->db[$dblinkname][$index]->dbname;
} else {
$dbhost = $CONFIG->db[$dblinkname]->dbhost;
$dbuser = $CONFIG->db[$dblinkname]->dbuser;
$dbpass = $CONFIG->db[$dblinkname]->dbpass;
$dbname = $CONFIG->db[$dblinkname]->dbname;
}
} else {
$dbhost = $CONFIG->dbhost;
$dbuser = $CONFIG->dbuser;
$dbpass = $CONFIG->dbpass;
$dbname = $CONFIG->dbname;
}
// Connect to database
if (!$dblink[$dblinkname] = mysql_connect($CONFIG->dbhost, $CONFIG->dbuser, $CONFIG->dbpass, true))
throw new DatabaseException("Elgg couldn't connect to the database using the given credentials.");
if (!mysql_select_db($CONFIG->dbname, $dblink[$dblinkname]))
throw new DatabaseException("Elgg couldn't select the database {$CONFIG->dbname}.");
}
/**
* Establish all database connections
*
* If the configuration has been set up for multiple read/write databases, set those
* links up separately; otherwise just create the one database link
*
*/
function setup_db_connections() {
// Get configuration and globalise database link
global $CONFIG, $dblink;
if (!empty($CONFIG->db->split)) {
establish_db_link('read');
establish_db_link('write');
} else {
establish_db_link('readwrite');
}
}
/**
* Alias to setup_db_connections, for use in the event handler
*
* @param string $event The event type
* @param string $object_type The object type
* @param mixed $object Used for nothing in this context
*/
function init_db($event, $object_type, $object = null) {
setup_db_connections();
}
/**
* Gets the appropriate db link for the operation mode requested
*
* @param string $dblinktype The type of link we want - "read", "write" or "readwrite" (the default)
* @return object Database link
*/
function get_db_link($dblinktype) {
global $dblink;
if (isset($dblink[$dblinktype])) {
return $dblink[$dblinktype];
} else {
return $dblink['readwrite'];
}
}
/**
* Use this function to get data from the database
* @param $query The query being passed.
* @return array An array of database result objects
*/
function get_data($query) {
global $dbcalls;
$dblink = get_db_link('read');
$resultarray = array();
$dbcalls++;
if ($result = mysql_query($query, $dblink)) {
while ($row = mysql_fetch_object($result)) {
$resultarray[] = $row;
}
}
if (empty($resultarray)) {
return false;
}
return $resultarray;
}
/**
* Use this function to get a single data row from the database
* @param $query The query to run.
* @result object A single database result object
*/
function get_data_row($query) {
global $dbcalls;
$dblink = get_db_link('read');
$dbcalls++;
if ($result = mysql_query($query, $dblink)) {
while ($row = mysql_fetch_object($result)) {
return $row;
}
}
return false;
}
/**
* Use this function to insert database data; returns id or false
*
* @param string $query The query to run.
* @return int $id the database id of the inserted row.
*/
function insert_data($query) {
global $dbcalls;
$dblink = get_db_link('write');
$dbcalls++;
if (mysql_query($query, $dblink)) {
return mysql_insert_id($dblink);
} else {
return false;
}
}
/**
* Update database data
*
* @param string $query The query to run.
* @result int|false Either the number of affected rows, or false on failure
*/
function update_data($query) {
global $dbcalls;
$dblink = get_db_link('write');
$dbcalls++;
if (mysql_query($query, $dblink))
return mysql_affected_rows();
return false;
}
/**
* Use this function to delete data
*
* @param string $query The SQL query to run
* @return int|false Either the number of affected rows, or false on failure
*/
function delete_data($query) {
global $dbcalls;
$dblink = get_db_link('write');
$dbcalls++;
if (mysql_query($query, $dblink)) {
return mysql_affected_rows();
} else {
return false;
}
}
/**
* Returns the number of rows returned by the last select statement, without the need to re-execute the query.
*
* @return int The number of rows returned by the last statement
*/
function count_last_select() {
$row = get_data_row("SELECT found_rows() as count");
if ($row)
return $row->count;
return 0;
}
/**
* Get the tables currently installed in the Elgg database
*
* @return array List of tables
*/
function get_db_tables() {
$result = get_data("show tables");
$result = (array) $result;
$tables = array();
if (is_array($result)) {
foreach($result as $row) {
foreach($row as $element) {
$tables[] = $element;
}
}
}
return $tables;
}
/**
* Get the last database error for a particular database link
*
* @param database link $dblink
* @return string Database error message
*/
function get_db_error($dblink) {
return mysql_error($dblink);
}
/**
* Runs a full database script from disk
*
* @param string $scriptlocation The full apth to the script
*/
function run_sql_script($scriptlocation) {
if ($script = file_get_contents($scriptlocation)) {
$errors = array();
$script = preg_replace('/\-\-.*\n/', '', $script);
$sql_statements = preg_split('/;[\n\r]+/', $script);
foreach($sql_statements as $statement) {
$statement = trim($statement);
if (!empty($statement)) {
$result = update_data($statement);
if ($result == false) {
$error = mysql_error();
$error = trim($error);
if (!empty($error)) {
$errors[] = $error;
}
}
}
}
if (!empty($errors)) {
$errortxt = "";
foreach($errors as $error)
$errortxt .= " {$error};";
throw new DatabaseException("There were a number of issues: " . $errortxt);
}
} else {
throw new DatabaseException("Elgg couldn't find the requested database script at {$scriptlocation}.");
}
}
// Stuff for initialisation
register_event_handler('init','system','init_db',0);
?>
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