pg_meta_data

(PHP 4 >= 4.3.0, PHP 5)

pg_meta_data Get meta data for table

Descrierea

array pg_meta_data ( resource $connection , string $table_name [, bool $extended ] )

pg_meta_data() returns table definition for table_name as an array.

Parametri

connection

PostgreSQL database connection resource.

table_name

The name of the table.

extended

Flag for returning extended meta data. Default to FALSE.

Valorile întoarse

An array of the table definition, or FALSE on error.

Exemple

Example #1 Getting table metadata

<?php
  $dbconn 
pg_connect("dbname=publisher") or die("Could not connect");

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

Exemplul de mai sus va afișa:

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

Istoria schimbărilor

Versiunea Descriere
5.6.0 No longer experimental. Added "is enum" as default attribute. extended flag is added.

Vedeți de asemenea

  • pg_convert() - Convert associative array values into suitable for SQL statement

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User Contributed Notes 4 notes

up
1
yarnofmoo at gmail dot com
7 years ago
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';
up
0
jsnell at e-normous dot com
6 years ago
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;
    }
up
0
dmiller at NOSPAM dot judcom dot nsw dot gov dot au
11 years ago
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
up
-1
rburghol at vt dot edu
9 years ago
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 ...
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