Sort the data in alphanumeric order using postgresql

Question

I am using php 5.3 for my code. and i want to sort my data in following format.

Building 01 - 101
Building 01 - 150

Building 02 - 100
Building 02 - 105
Building 03 - 099

public static function fetchSortedPropertyUnits() {
    $strSql = 'SELECT pu.*,pb.building_name
               FROM property_units pu  
                LEFT JOIN property_buildings pb ON( pu.property_building_id = pb.id )  
                WHERE pu.management_company_id = ' . $intManagementCompanyId . '
                    AND pu.property_id = ' . $intPropertyId . '  
               ORDER BY  
                COALESCE ( CAST ( SUBSTRING ( pb.building_name FROM \'([a-zA-Z ]{1,26})\' ) AS VARCHAR ), \'\' ),
                    COALESCE ( CAST ( SUBSTRING ( pb.building_name FROM \'([0-9]{1,10})\' ) AS INTEGER ), 0 ),
                    COALESCE ( CAST ( SUBSTRING ( pu.unit_number FROM \'([a-zA-Z ]{1,26})\' ) AS VARCHAR ), \'\' ),
                    COALESCE ( CAST ( SUBSTRING ( pu.unit_number FROM \'([0-9]{1,10})\' ) AS INTEGER ), 0 ),
                    pb.building_name,
                    pu.unit_number';  
            return self::fetchPropertyUnits( $strSql, $objDatabase );  }

This is the fetch function i used.
& i use it in my code as follows.

$arrobjSortedPropertyUnits  =   CPropertyUnits::fetchSortedPropertyUnits( $this->m_objPropertyUtilitySetting->getManagementCompanyId(), $this->m_objPropertyUtilitySetting->getPropertyId(), $this->m_objClientDatabase );  
foreach( $this->m_arrobjPropertyUnits as $objPropertyUnit ) {  
    $strUnitNumber = $objPropertyUnit->getUnitNumber();  
    if( true == valObj( $objPropertyUnit, 'CPropertyUnit' ) && true == $objPropertyUnit->getPropertyBuildingId() ) {  
        $strUnitNumber = $objPropertyUnit->getBuildingName() . ' - ' . $objPropertyUnit->getUnitNumber();  
        $objPropertyUnit->setUnitNumber( $strUnitNumber );  
    }  
}  

I want to sort it in proper order, if property don't have building then only sort it by unit numbers. Any help is welcome for this issue. Thanks.

Answer 1

In this case you need to look at your strings and see how to process them. it looks like have a string in the form of "Building X - Y" and you want to sort on X then Y. The simple thing to do is to turn this into a numeric array. You can do this by:

 .....
 ORDER BY string_to_array(regexp_replace(building_name, 'Building ', ''), ' - ')::int[]

This will turn "Building X - Y" into {X,Y} so Building 1 - 100 becomes {1,100} and so forth. These will be ordered starting with the left-most element.