Урок - Database Utility Class

Главная » Курсы » Курс CodeIgniter® 2.2 » Урок - Database Utility Class

Обучающий онлайн курс
CodeIgniter® 2.2

Обучающий курс по CMF CodeIgniter® 2.2.
Лицензия: Лицензия Creative Commons.

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

Table of Contents

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()

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

$this->dbutil->some_function()

$this->dbutil->list_databases()

Returns an array of database names:

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

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

$this->dbutil->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 table you are looking for. This function is case sensitive.

$this->dbutil->optimize_table('table_name');

Note:  This features is only available for MySQL/MySQLi databases.

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.

$this->dbutil->repair_table('table_name');

Note:  This features is only available for MySQL/MySQLi databases.

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.

$this->dbutil->optimize_database();

Note:  This features is only available for MySQL/MySQLi databases.

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 table optimization.

$this->dbutil->csv_from_result($db_result)

Permits you to generate a CSV file from a query result. The first parameter of the function 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 and third parameters allows you to set the delimiter and newline character. By default tabs are used as the delimiter and "\n" is used as a new line. Example:

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

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

Important:  This function 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.

$this->dbutil->xml_from_result($db_result)

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 function 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.

$this->dbutil->backup()

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

Note:  This features is only available for MySQL databases.

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 function. 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

PreferenceDefault ValueOptionsDescription
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.