/**
*
* @param array $columns
* @return type
* @throws Exception@brief Load the totals for the current found set using MySQL's aggregate
* operators. This method will always query the database directly (no caching).
*
* <p>This method was developed to make it easier to create "totals" rows in the
* list view.</p>
*
* <h3>Example</h3>
*
* @code
* $resultSet = Dataface_Application::getInstance()->getResultSet();
* $results = $resultSet->loadTotals(array(
* 'age#avg',
* 'age#std',
* 'income#sum'
* ));
* print_r($results);
* @endcode
*
* <p>Output:</p>
*
* @code
* array(
* 'age_AVG' => 74.4,
* 'age_STD' => 13.2,
* 'income_SUM' => 100567
* );
* @endcode
*
* @param array $columns A list of strings of the form {fieldname}#{operator} where
* where {fieldname} is the name of a field and {operator} is the name of an operator
* to apply to the field.
*
* <h3>Available Operators</h3>
* <table>
* <tr>
* <th>Operator</th><th>Description</th>
* </tr>
* <tr>
* <td>sum</td><td>The sum of field values for result set.</td>
* </tr>
* <tr>
* <td>avg</td><td>The average value of field in result set.</td>
* <tr>
* <td>max</td><td>The max value of field in result set.</td>
* </tr>
* <tr>
* <td>min</td><td>The minimum value of field result set.</td>
* </tr>
* <tr>
* <td>bit_and</td><td>Result of bitwise AND on field for all found records.</td>
* </tr>
* <tr>
* <td>bit_or</td><td>Result of bitwise OR on field for all found records.</td>
* </tr>
* <tr>
* <td>bit_xor</td><td>Result of bitwise XOR on field for all found records.</td>
* </tr>
* <tr>
* <td>group_concat</td><td>The concatenation of all rows in found set for field. Joined with a comma.</td>
* </tr>
* <tr>
* <td>std</td><td>Population Standard deviation of field values for result set.</td>
* </tr>
* <tr>
* <td>stddev_samp</td><td>Sample Standard deviation of field values for result set.</td>
* </tr>
* <tr>
* <td>stddev_pop</td><td>Same as stddev</td>
* </tr>
* <tr>
* <td>var_pop<td><td>Population standard variance for field values for result set.</td>
* </tr>
* <tr>
* <td>var_samp</td><td>Sample standard deviation for field values for result set.</td>
* </tr>
* <tr>
* <td>variance</td><td>Same as var_pop</td>
* </tr>
* </table>
*
*
* @return Associative array where the keys have the form {fieldname}_{operator|uppercase} and the values
* are the corresponding result of the operator on that field. E.g. If your input was array('field1#sum', 'field2#avg')
* the output woult be array('field1_SUM' => {some number}, 'field2_AVG' => {some_number})
*
* @since 2.0.4
* @see Dataface_QueryBuilder::select_totals()
*/
function loadTotals($columns = array())
{
$builder = new Dataface_QueryBuilder($this->_tablename, $this->_query);
$sql = $builder->select_totals(array(), null, $columns);
$res = df_query($sql);
if (!$res) {
throw new Exception(xf_db_error(df_db()));
} else {
$out = xf_db_fetch_assoc($res);
@xf_db_free_result($res);
return $out;
}
}
