# 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 table 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 table 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.

Eg. $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.