XXVII. dbx Functions

IntroducciÃ³n

The dbx module is a database abstraction layer (db 'X', where 'X' is a supported database). The dbx functions allow you to access all supported databases using a single calling convention. The dbx-functions themselves do not interface directly to the databases, but interface to the modules that are used to support these databases.

Nota: This extension has been moved to the PECL repository and is no longer bundled with PHP as of PHP 5.1.0.

Requisitos

To be able to use a database with the dbx-module, the module must be either linked or loaded into PHP, and the database module must be supported by the dbx-module. Currently, the following databases are supported, but others will follow:

FrontBase (available from PHP 4.1.0).
Microsoft SQL Server
MySQL
ODBC
PostgreSQL
Sybase-CT (available from PHP 4.2.0).
Oracle (oci8) (available from PHP 4.3.0).
SQLite (PHP 5).

Documentation for adding additional database support to dbx can be found at http://www.guidance.nl/php/dbx/doc/.

InstalaciÃ³n

In order to have these functions available, you must compile PHP with dbx support by using the --enable-dbx option and all options for the databases that will be used, e.g. for MySQL you must also specify --with-mysql=[DIR]. To get other supported databases to work with the dbx-module refer to their specific documentation.

ConfiguraciÃ³n en tiempo de ejecuciÃ³n

El comportamiento de estas funciones estÃ¡ afectado por los valores definidos en php.ini.

Tabla 1. DBX Configuration Options

Name	Default	Changeable	Changelog
dbx.colnames_case	"unchanged"	PHP_INI_SYSTEM	Available since PHP 4.3.0.

For further details and definitions of the PHP_INI_* constants, see the ApÃ©ndice G.

A continuaciÃ³n se presenta una corta explicaciÃ³n de las directivas de configuraciÃ³n.

dbx.colnames_case string: Columns names can be returned "unchanged" or converted to "uppercase" or "lowercase". This directive can be overridden with a flag to dbx_query().

Tipos de recursos

There are two resource types used in the dbx module. The first one is the link-object for a database connection, the second a result-object which holds the result of a query.

Constantes predefinidas

Estas constantes estÃ¡n definidas por esta extensiÃ³n y estarÃ¡n disponibles solamente cuando la extensiÃ³n ha sido o bien compilada dentro de PHP o grabada dinÃ¡micamente en tiempo de ejecuciÃ³n.

DBX_MYSQL (integer)
DBX_ODBC (integer)
DBX_PGSQL (integer)
DBX_MSSQL (integer)
DBX_FBSQL (integer)
DBX_OCI8 (integer) (available from PHP 4.3.0)
DBX_SYBASECT (integer)
DBX_SQLITE (integer) (PHP 5)
DBX_PERSISTENT (integer)
DBX_RESULT_INFO (integer)
DBX_RESULT_INDEX (integer)
DBX_RESULT_ASSOC (integer)
DBX_RESULT_UNBUFFERED (integer) (PHP 5)
DBX_COLNAMES_UNCHANGED (integer) (available from PHP 4.3.0)
DBX_COLNAMES_UPPERCASE (integer) (available from PHP 4.3.0)
DBX_COLNAMES_LOWERCASE (integer) (available from PHP 4.3.0)
DBX_CMP_NATIVE (integer)
DBX_CMP_TEXT (integer)
DBX_CMP_NUMBER (integer)
DBX_CMP_ASC (integer)
DBX_CMP_DESC (integer)

Tabla de contenidos
dbx_close -- Close an open connection/database
dbx_compare -- Compare two rows for sorting purposes
dbx_connect -- Open a connection/database
dbx_error -- Report the error message of the latest function call in the module (not just in the connection)
dbx_escape_string -- Escape a string so it can safely be used in an sql-statement
dbx_fetch_row -- Fetches rows from a query-result that had the DBX_RESULT_UNBUFFERED flag set
dbx_query -- Send a query and fetch all results (if any)
dbx_sort -- Sort a result from a dbx_query by a custom sort function

add a note User Contributed Notes
dbx Functions

bart at mediawave dot nl
08-Jul-2004 06:45


Simple function for returning paged result sets.





<?php 


// use: pagedQuery($link, $sql, $rows_per_page, $current_page)





function pagedQuery($link, $sql, $nrows = 10, $page = 1) {


    $handle = dbx_query($link, $sql, DBX_RESULT_UNBUFFERED);


    $result = new stdClass;


    $result->link = $this->link;


    $result->page = $page;


    $result->data = array();


    $result->info['name'] = array();


    $start = ($page - 1) * $nrows;


    $end = $start + $nrows;


    $result->rows = 0;


    while ($row = dbx_fetch_row($handle)) {


        $result->rows++;


        if (($result->rows > $start) && ($result->rows <= $end)) {


            $result->data[] = $row;            


        }


    }


    if ($result->data[0]) {


        $result->cols = count($result->data[0]) / 2;


        $result->info['name'] = array_slice(array_keys($result->data[0]), $result->cols, $result->cols);


        $result->lastPage = ceil($result->rows / $nrows);


    }


    return $result;


}


?>

bart at mediawave dot nl
01-Jul-2004 08:12


Would like to confirm that dbx is at least three times faster than adodb with my application. However, once loaded, adodb has much more features and probably performs better in some situations then dbx.



One of the nice features that adodb has, is the way you can quickly make a dropdown menu from a query. Here's a similar function that works with a dbx result object:



<?php



// $result is the dbx_query result (It expects two fields)

// $name is the name of the dropdown field

// $selected is the option that should be selected

// $firstrow takes a string like "myvalue:myname"

// $attr can be used to add some extra attributes



function dropDown($result, $name, $selected, $firstRow, $attr) {

    $s = '<select name="'.$name.'" '.$attr.'>';

    if (is_string($firstRow))  {

        $row = explode(':', $firstRow);

        $s .= '<option value="'.$row[0].'">'.$row[1].'</option>';

    } else

        $s .= '<option></option>';

    foreach ($result->data as $row) {

        if ($row[0] == $selected)

            $s .= '<option value="'.$row[0].'" selected="selected">'.htmlspecialchars($row[1]).'</option>';

        else

            $s .= '<option value="'.$row[0].'">'.htmlspecialchars($row[1]).'</option>';

    }

    return $s.'</select>';

}



?>

rhcf at linux dot ime dot usp dot br
25-Nov-2003 01:52


BEWARE!!!



dbx_query allocate all retrieved data in an array on memory. If the query result is big (bigger then the memory_limit on php.ini), the result will be empty. So use dbx wih care.

carl [at] carlthompson [dot] net
07-Jun-2003 01:49


The above benchmark is very misleading. Unfortunately, I found out the hard way by porting my app to ADODB. Most PHP apps are going to be very short-lived therefore startup / setup time is a large factor. This benchmark does not measure that. Just include()ing the main ADODB file added 27ms to my app's startup time! Considering my app took only 16ms to run in total using DBX, the idea of switching to ADODB was DOA before running a single query.



In the end, the total time for my app went from 16ms with DBX to 49ms with ADODB. ADODB's powerful features are obviously not worth that kind of overhead.



Carl Thompson

jlim at natsoft dot com dot my
06-Feb-2003 07:35


For some benchmarks of dbx connecting to mysql compared to native mysql api, adodb, and others, see:


http://phplens.com/lens/adodb/


http://php.weblogs.com/2003/02/06#a2336

add a note

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