Introduction

These functions build the foundation for accessing Berkeley DB style databases.

This is a general abstraction layer for several file-based databases. As such, functionality is limited to a common subset of features supported by modern databases such as Sleepycat Software's DB2. (This is not to be confused with IBM's DB2 software, which is supported through the ODBC functions.)

Requirements

The behaviour of various aspects depends on the implementation of the underlying database. Functions such as dba_optimize() and dba_sync() will do what they promise for one database and will do nothing for others. You have to download and install supported dba-Handlers.

When invoking the dba_open() or dba_popen() functions, one of the handler names must be supplied as an argument. The actually available list of handlers is displayed by invoking phpinfo() or dba_handlers().

Installation

By using the --enable-dba=shared configuration option you can build a dynamic loadable module to enable PHP for basic support of dbm-style databases. You also have to add support for at least one of the following handlers by specifying the --with-XXXX configure switch to your PHP configure line.

Runtime Configuration

This extension has no configuration directives defined in php.ini.

Resource Types

The functions dba_open() and dba_popen() return a handle to the specified database file to access which is used by all other dba-function calls.

Predefined Constants

This extension has no constants defined.

Examples

<?php

$id = dba_open("/tmp/test.db", "n", "db2");

if (!$id) {
    echo "dba_open failed\n";
    exit;
}

dba_replace("key", "This is an example!", $id);

if (dba_exists("key", $id)) {
    echo dba_fetch("key", $id);
    dba_delete("key", $id);
}

dba_close($id);
?>

DBA is binary safe and does not have any arbitrary limits. However, it inherits all limits set by the underlying database implementation.

All file-based databases must provide a way of setting the file mode of a new created database, if that is possible at all. The file mode is commonly passed as the fourth argument to dba_open() or dba_popen().

You can access all entries of a database in a linear way by using the dba_firstkey() and dba_nextkey() functions. You may not change the database while traversing it.

<?php

// ...open database...

$key = dba_firstkey($id);

while ($key != false) {
    if (true) {          // remember the key to perform some action later
        $handle_later[] = $key;
    }
    $key = dba_nextkey($id);
}

foreach ($handle_later as $val) {
    dba_delete($val, $id);
}

?>