XIX. Funzioni DBM

Questa funzioni consentono lo storage di records memorizzati in un dbm-style database. Questo tipo di database (supportato da Berkeley DB, GDBM, e qualche libreria di sistema, cos� come una built-in flatfile library) memorizza coppie key/value (al contrario dei full-blown records supportati dai database relazionali).

Esempio 1. Esempio DBM

$dbm = dbmopen ("lastseen", "w"); if (dbmexists ($dbm, $userid)) { $last_seen = dbmfetch ($dbm, $userid); } else { dbminsert ($dbm, $userid, time()); } do_stuff(); dbmreplace ($dbm, $userid, time()); dbmclose ($dbm);

Sommario
dblist -- Descrive la libreria DBM-compatibile in uso.
dbmclose -- Chiude un database dbm
dbmdelete -- Cancella il valore per una chiave da un database DBM
dbmexists -- Dice se esiste un valore per una chiave in un database DBM
dbmfetch -- Estrae un valore per una chiave da un database DBM
dbmfirstkey -- Recupera la prima chiave da un database DBM
dbminsert -- Inserisce un valore per una chiave in un database DBM
dbmnextkey -- Recupera la chiave successiva da un database DBM
dbmopen -- Apre un database DBM
dbmreplace -- Sostituisce il valore per una chiave in un database DBM

add a note User Contributed Notes
Funzioni DBM

foripepe at yahoo dot com
28-Feb-2002 04:16


First:

Make a firstdbm.db file.

Set attribute Read and Write.



--------------------------------------



<html><body>



<?

$dbm = dbmopen("firstdbm","w");

echo "<b>\$dbm: $dbm = dbmopen(\"firstdbm\", \"w\");</b>< br>";

echo "<i>".dblist()." = dblist();</i>< br>< br>";



$fruit = "apple";

$colour = "red";

if (dbmexists ($dbm, $fruit)) {

  $colour = dbmfetch ($dbm, $fruit);

  echo "\$colour: $colour = dbmfetch(\$dbm: $dbm, \$fruit: $fruit);< br>";

  $key = dbmreplace($dbm, $fruit, "green");

  echo "\$key: $key = dbmreplace(\$dbm: $dbm, \$fruit: $fruit, \"green\");< br>";

  $colour = dbmfetch ($dbm, $fruit);

  echo "\$colour: $colour = dbmfetch(\$dbm: $dbm, \$fruit: $fruit);< br>";

  if ( !dbmdelete($dbm, $fruit) ) {

    echo "False (OK) = dbmdelete(\$dbm: $dbm, \$fruit: $fruit);< br>";

  } else {

    echo "True (NOT OK) = dbmdelete(\$dbm: $dbm, \$fruit: $fruit);< br>";

  }

  $colour = dbmfetch ($dbm, $fruit);

  echo "\$color: $colour = dbmfetch(\$dbm: $dbm, \$fruit: $fruit);< br><hr>";

  $i = 1;

  $key = dbmfirstkey($dbm);

  while ($key) {

    if ($i==1) {

      echo "\$key: $key = dbmfirstkey(\$dbm: $dbm);< br>";

    } else {

      echo "\$key: $key = dbmnextkey(\$dbm: $dbm);< br>";

    }

    $i++;

    $colour = dbmfetch ($dbm, $key);

    echo "\$colour: $colour = dbmfetch(\$dbm: $dbm, \$key: $key);< br>";

    $key = dbmnextkey($dbm,$key);

  }

} else {

  dbminsert ($dbm, $fruit, $colour);

  echo "dbminsert(\$dbm: $dbm, \$fruit: $fruit, \$colour: $colour);< br>";

  dbminsert ($dbm, "pear", "yellow");

  echo "dbminsert(\$dbm: $dbm, \"pear\", \"yellow\");< br>";

  dbminsert ($dbm, "apricot", "pink");

  echo "dbminsert(\$dbm: $dbm, \"apricot\", \"pink\");< br><hr>";

  $i = 1;

  $key = dbmfirstkey($dbm);

  while ($key) {

    if ($i==1) {

      echo "\$key: $key = dbmfirstkey(\$dbm: $dbm);< br>";

    } else {

      echo "\$key: $key = dbmnextkey(\$dbm: $dbm);< br>";

    }

    $i++;

    $colour = dbmfetch ($dbm, $key);

    echo "\$colour: $colour = dbmfetch(\$dbm: $dbm, \$key: $key);< br>";

    $key = dbmnextkey($dbm,$key);

  }

}



echo "< br>";

if (dbmclose ($dbm)) {

  echo "<b>True (OK) = dbmclose(\$dbm: $dbm);</b>< br>";

} else {

  echo "<b>False (NOT OK) = dbmclose(\$dbm: $dbm);</b>< br>";

};

?>



</body></html>



--------------------------------------

The first run output:



$dbm: 1 = dbmopen("firstdbm", "w");

ndbm support enabled = dblist();



dbminsert($dbm: 1, $fruit: apple, $colour: red);

dbminsert($dbm: 1, "pear", "yellow");

dbminsert($dbm: 1, "apricot", "pink");



$key: pear = dbmfirstkey($dbm: 1);

$colour: yellow = dbmfetch($dbm: 1, $key: pear);

$key: apricot = dbmnextkey($dbm: 1);

$colour: pink = dbmfetch($dbm: 1, $key: apricot);

$key: apple = dbmnextkey($dbm: 1);

$colour: red = dbmfetch($dbm: 1, $key: apple);



True (OK) = dbmclose($dbm: 1);



--------------------------------------

The second run output:



$dbm: 1 = dbmopen("firstdbm", "w");

ndbm support enabled = dblist();



$colour: red = dbmfetch($dbm: 1, $fruit: apple);

$key: 0 = dbmreplace($dbm: 1, $fruit: apple, "green");

$colour: green = dbmfetch($dbm: 1, $fruit: apple);

False (OK) = dbmdelete($dbm: 1, $fruit: apple);

$color: = dbmfetch($dbm: 1, $fruit: apple);



$key: pear = dbmfirstkey($dbm: 1);

$colour: yellow = dbmfetch($dbm: 1, $key: pear);

$key: apricot = dbmnextkey($dbm: 1);

$colour: pink = dbmfetch($dbm: 1, $key: apricot);



True (OK) = dbmclose($dbm: 1);

jb at abzone dot cz
05-Oct-2001 04:27


NOTE: DBM and DBA are two different extensions which must


      be configured separately.





Hi *,


names of these functions was changed in PHP4.


Refer to http://www.faqts.com/knowledge_base/view.phtml/aid/1988 


or http://www.zend.com/manual/ref.dba.php .


Regards Jindra

mouse at bloodletting dot com
07-Jul-2001 12:23


Be advised that almost every function in this section either has no documentation or incorrectly documented regarding return codes.  If you want to use the DB methods safely you will have to reverse engineer the return codes and hope that they do not change values returned by the functions in the future to match the incorrect documentation.





In my experience, the return code of 0 or FALSE indicates no error.  This matches the behavior of GDBM which I am using as my underlying DB manager.  This may not be true for people using another manager, or the builtin flatfile code.

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