Database Utility Class
**********************

The Database Utility Class contains methods that help you manage your
database.

* Initializing the Utility Class

* Using the Database Utilities

  * Retrieve list of database names

  * Determine If a Database Exists

  * Optimize a Table

  * Repair a Table

  * Optimize a Database

  * Export a Query Result as a CSV File

  * Export a Query Result as an XML Document

* Backup Your Database

  * Database Backup Notes

  * Usage Example

  * Setting Backup Preferences

  * Description of Backup Preferences

* Class Reference


Initializing the Utility Class
==============================

Important:

  In order to initialize the Utility class, your database driver must
  already be running, since the utilities class relies on it.

Load the Utility Class as follows:

   $this->load->dbutil();

You can also pass another database object to the DB Utility loader, in
case the database you want to manage isn’t the default one:

   $this->myutil = $this->load->dbutil($this->other_db, TRUE);

In the above example, we’re passing a custom database object as the
first parameter and then tell it to return the dbutil object, instead
of assigning it directly to "$this->dbutil".

Note:

  Both of the parameters can be used individually, just pass an empty
  value as the first one if you wish to skip it.

Once initialized you will access the methods using the "$this->dbutil"
object:

   $this->dbutil->some_method();


Using the Database Utilities
============================


Retrieve list of database names
-------------------------------

Returns an array of database names:

   $dbs = $this->dbutil->list_databases();

   foreach ($dbs as $db)
   {
           echo $db;
   }


Determine If a Database Exists
------------------------------

Sometimes it’s helpful to know whether a particular database exists.
Returns a boolean TRUE/FALSE. Usage example:

   if ($this->dbutil->database_exists('database_name'))
   {
           // some code...
   }

Note:

  Replace *database_name* with the name of the database you are
  looking for. This method is case sensitive.


Optimize a Table
----------------

Permits you to optimize a table using the table name specified in the
first parameter. Returns TRUE/FALSE based on success or failure:

   if ($this->dbutil->optimize_table('table_name'))
   {
           echo 'Success!';
   }

Note:

  Not all database platforms support table optimization. It is mostly
  for use with MySQL.


Repair a Table
--------------

Permits you to repair a table using the table name specified in the
first parameter. Returns TRUE/FALSE based on success or failure:

   if ($this->dbutil->repair_table('table_name'))
   {
           echo 'Success!';
   }

Note:

  Not all database platforms support table repairs.


Optimize a Database
-------------------

Permits you to optimize the database your DB class is currently
connected to. Returns an array containing the DB status messages or
FALSE on failure.

   $result = $this->dbutil->optimize_database();

   if ($result !== FALSE)
   {
           print_r($result);
   }

Note:

  Not all database platforms support database optimization. It it is
  mostly for use with MySQL.


Export a Query Result as a CSV File
-----------------------------------

Permits you to generate a CSV file from a query result. The first
parameter of the method must contain the result object from your
query. Example:

   $this->load->dbutil();

   $query = $this->db->query("SELECT * FROM mytable");

   echo $this->dbutil->csv_from_result($query);

The second, third, and fourth parameters allow you to set the
delimiter newline, and enclosure characters respectively. By default
commas are used as the delimiter, “n” is used as a new line, and a
double-quote is used as the enclosure. Example:

   $delimiter = ",";
   $newline = "\r\n";
   $enclosure = '"';

   echo $this->dbutil->csv_from_result($query, $delimiter, $newline, $enclosure);

Important:

  This method will NOT write the CSV file for you. It simply creates
  the CSV layout. If you need to write the file use the File Helper.


Export a Query Result as an XML Document
----------------------------------------

Permits you to generate an XML file from a query result. The first
parameter expects a query result object, the second may contain an
optional array of config parameters. Example:

   $this->load->dbutil();

   $query = $this->db->query("SELECT * FROM mytable");

   $config = array (
           'root'          => 'root',
           'element'       => 'element',
           'newline'       => "\n",
           'tab'           => "\t"
   );

   echo $this->dbutil->xml_from_result($query, $config);

Important:

  This method will NOT write the XML file for you. It simply creates
  the XML layout. If you need to write the file use the File Helper.


Backup Your Database
====================


Database Backup Notes
---------------------

Permits you to backup your full database or individual tables. The
backup data can be compressed in either Zip or Gzip format.

Note:

  This feature is only available for MySQL and Interbase/Firebird
  databases.

Note:

  For Interbase/Firebird databases, the backup file name is the only
  parameter.$this->dbutil->backup(‘db_backup_filename’);

Note:

  Due to the limited execution time and memory available to PHP,
  backing up very large databases may not be possible. If your
  database is very large you might need to backup directly from your
  SQL server via the command line, or have your server admin do it for
  you if you do not have root privileges.


Usage Example
-------------

   // Load the DB utility class
   $this->load->dbutil();

   // Backup your entire database and assign it to a variable
   $backup = $this->dbutil->backup();

   // Load the file helper and write the file to your server
   $this->load->helper('file');
   write_file('/path/to/mybackup.gz', $backup);

   // Load the download helper and send the file to your desktop
   $this->load->helper('download');
   force_download('mybackup.gz', $backup);


Setting Backup Preferences
--------------------------

Backup preferences are set by submitting an array of values to the
first parameter of the "backup()" method. Example:

   $prefs = array(
           'tables'        => array('table1', 'table2'),   // Array of tables to backup.
           'ignore'        => array(),                     // List of tables to omit from the backup
           'format'        => 'txt',                       // gzip, zip, txt
           'filename'      => 'mybackup.sql',              // File name - NEEDED ONLY WITH ZIP FILES
           'add_drop'      => TRUE,                        // Whether to add DROP TABLE statements to backup file
           'add_insert'    => TRUE,                        // Whether to add INSERT data to backup file
           'newline'       => "\n"                         // Newline character used in backup file
   );

   $this->dbutil->backup($prefs);


Description of Backup Preferences
---------------------------------

+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| Preference              | Default Value           | Options                 | Description                                                               |
|=========================|=========================|=========================|===========================================================================|
| **tables**              | empty array             | None                    | An array of tables you want backed up. If left blank all tables will be   |
|                         |                         |                         | exported.                                                                 |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **ignore**              | empty array             | None                    | An array of tables you want the backup routine to ignore.                 |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **format**              | gzip                    | gzip, zip, txt          | The file format of the export file.                                       |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **filename**            | the current date/time   | None                    | The name of the backed-up file. The name is needed only if you are using  |
|                         |                         |                         | zip compression.                                                          |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **add_drop**            | TRUE                    | TRUE/FALSE              | Whether to include DROP TABLE statements in your SQL export file.         |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **add_insert**          | TRUE                    | TRUE/FALSE              | Whether to include INSERT statements in your SQL export file.             |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **newline**             | “\n”                    | “\n”, “\r”, “\r\n”      | Type of newline to use in your SQL export file.                           |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+
| **foreign_key_checks**  | TRUE                    | TRUE/FALSE              | Whether output should keep foreign key checks enabled.                    |
+-------------------------+-------------------------+-------------------------+---------------------------------------------------------------------------+


Class Reference
===============

class CI_DB_utility

   backup([$params = array()])

      Parameters:
         * **$params** ("array") – An associative array of options

      Returns:
         raw/(g)zipped SQL query string

      Return type:
         "string"

      Perform a database backup, per user preferences.

   database_exists($database_name)

      Parameters:
         * **$database_name** ("string") – Database name

      Returns:
         TRUE if the database exists, FALSE otherwise

      Return type:
         "bool"

      Check for the existence of a database.

   list_databases()

      Returns:
         Array of database names found

      Return type:
         "array"

      Retrieve a list of all the database names.

   optimize_database()

      Returns:
         Array of optimization messages or FALSE on failure

      Return type:
         "array"

      Optimizes the database.

   optimize_table($table_name)

      Parameters:
         * **$table_name** ("string") – Name of the table to optimize

      Returns:
         Array of optimization messages or FALSE on failure

      Return type:
         "array"

      Optimizes a database table.

   repair_table($table_name)

      Parameters:
         * **$table_name** ("string") – Name of the table to repair

      Returns:
         Array of repair messages or FALSE on failure

      Return type:
         "array"

      Repairs a database table.

   csv_from_result($query[, $delim = ', '[, $newline = "\n"[, $enclosure = '"']]])

      Parameters:
         * **$query** ("object") – A database result object

         * **$delim** ("string") – The CSV field delimiter to use

         * **$newline** ("string") – The newline character to use

         * **$enclosure** ("string") – The enclosure delimiter to use

      Returns:
         The generated CSV file as a string

      Return type:
         "string"

      Translates a database result object into a CSV document.

   xml_from_result($query[, $params = array()])

      Parameters:
         * **$query** ("object") – A database result object

         * **$params** ("array") – An associative array of preferences

      Returns:
         The generated XML document as a string

      Return type:
         "string"

      Translates a database result object into an XML document.
