pg_meta_data

(PHP 4 >= 4.3.0, PHP 5)

pg_meta_data — Lit les métadonnées de la table PostgreSQL

Description

array pg_meta_data ( resource $connection , string $table_name )

pg_meta_data() retourne la définition de la table table_name sous forme de tableau.

Avertissement

Cette fonction est EXPERIMENTALE. Cela signifie que le comportement de cette fonction, son nom et, concrètement, TOUT ce qui est documenté ici peut changer dans un futur proche, SANS PREAVIS ! Soyez-en conscient, et utilisez cette fonction à vos risques et périls.

Liste de paramètres

connection: Ressource de connexion de base de données PostgreSQL.
table_name: Le nom de la table.

Valeurs de retour

Un tableau de la table de définition ou FALSE en cas d'erreur.

Exemples

Exemple #1 Récupération des métadonnées d'une table


<?php
  $dbconn = pg_connect("dbname=publisher") or die("Connexion impossible");

  $meta = pg_meta_data($dbconn,'auteurs');
  if (is_array ($meta)) {
       echo '<pre>';
       var_dump ($meta);
       echo '</pre>';
  }
?>

L'exemple ci-dessus va afficher :

array(3) {
["auteur"]=>
array(5) {
  ["num"]=>
  int(1)
  ["type"]=>
  string(7) "varchar"
  ["len"]=>
  int(-1)
  ["not null"]=>
  bool(false)
  ["has default"]=>
  bool(false)
}
["annee"]=>
array(5) {
  ["num"]=>
  int(2)
  ["type"]=>
  string(4) "int2"
  ["len"]=>
  int(2)
  ["not null"]=>
  bool(false)
  ["has default"]=>
  bool(false)
}
["titre"]=>
array(5) {
  ["num"]=>
  int(3)
  ["type"]=>
  string(7) "varchar"
  ["len"]=>
  int(-1)
  ["not null"]=>
  bool(false)
  ["has default"]=>
  bool(false)
}
}

Voir aussi

pg_convert() - Convertit des tableaux associatifs en une commande PostgreSQL

pg_num_fields

pg_lo_write

Last updated: Fri, 14 Aug 2009

add a note User Contributed Notes
pg_meta_data

jsnell at e-normous dot com
12-Nov-2007 11:24


The built in function does not provide any support for selecting a schema.  If you need schema support and do not want to alter your SEARCH_PATH, the following function can provide it:



 function meta_data($table, $schema = 'public')

    {

$result = pg_query_params("SELECT a.attname, a.attnum, t.typname, a.attlen, a.attnotNULL, a.atthasdef, a.attndims 

FROM pg_class as c, pg_attribute a, pg_type t, pg_namespace n

WHERE a.attnum > 0 

AND a.attrelid = c.oid 

AND c.relname = $1

AND a.atttypid = t.oid 

AND n.oid = c.relnamespace

AND n.nspname = $2

ORDER BY a.attnum", array($table, $schema));

$fields = array();

while($row = pg_fetch_array()) {

$fields['attname'] = $row;

} 

        return $fields;

    }

yarnofmoo at gmail dot com
27-Jun-2007 03:32


You can get some possibly more useful information with the query:



SELECT table_name, column_name, data_type, character_maximum_length FROM information_schema.columns WHERE table_name='tablename';

rburghol at vt dot edu
24-Jun-2005 01:37


When querying on meta data from a temp table, the meta data seems to persist even if a fresh connection is established, where the temp table no longer exists.



 For example, if you create a connection and a temp table like so:

$dbconn1 = pg_connect('blah blah', , PGSQL_CONNECT_FORCE_NEW);

pg_exec($dbconn1,'create temp table foo as select 'foo' as namecol, 'bar' as valcol');



Then create a new connection



$dbconn2 = pg_connect('blah blah', , PGSQL_CONNECT_FORCE_NEW);



And query the meta data for table 'foo' in this new connection, it will report the facts about this table:

pg_meta_data($dbconn2,'foo');



"'Array ( [foo] => Array ( [num] => 1 [type] => varchar... "



However, trying to remove this table:

pg_exec($dbconn,'drop table foo');



Throws an error:

pg_exec(): Query failed: ERROR: table "foo" does not exist in ...

dmiller at NOSPAM dot judcom dot nsw dot gov dot au
18-Jun-2003 08:31


This function seems to be case-sensitive on tablename (php-4.3.1)



The Array returned is of the following structure

['field name'] => Array

   (

     ['num'] => Field number starting at 1

     ['type'] => data type, eg varchar, int4

     ['len'] => internal storage size of field. -1 for varying

     ['not null'] => boolean

     ['has default'] => boolean

   )

     ......



for Varied size datatypes (varchar, text, etc) 

you can get the max data length from the system table pg_attribute.atttypmod -4

eg. 

select attnum, attname , atttypmod -4 as field_len 

from pg_attribute, pg_class 

where relname='$tablename' 

and attrelid=relfilenode 

and attnum>=1

add a note

pg_num_fields

pg_lo_write

Last updated: Fri, 14 Aug 2009