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pg_meta_data

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

pg_meta_data テーブルからメタデータを取得する

説明

pg_meta_data(PgSql\Connection $connection, string $table_name, bool $extended = false): array|false

pg_meta_data() は、table_name のテーブル定義を配列として返します。

パラメータ

connection

PgSql\Connection クラスのインスタンス。

table_name

テーブルの名前。

extended

拡張メタデータを返すかどうかを表すフラグ。デフォルトは false

戻り値

テーブル定義の配列を返します。 失敗した場合に false を返します

変更履歴

バージョン 説明
8.1.0 connection は、PgSql\Connection クラスのインスタンスを期待するようになりました。 これより前のバージョンでは、リソース を期待していました。

例1 テーブルのメタデータを得る

<?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>';
}
?>

上の例の出力は以下となります。

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)
}
}

参考

  • pg_convert() - 連想配列の値を、SQL 文として実行可能な形式に変換する

add a note

User Contributed Notes 6 notes

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2
yarnofmoo at gmail dot com
16 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
shaman_master at list dot ru
5 years ago
If parameter $extended not false:
<?php
array (size=2)
'name' =>
array (
size=11)
'num' => int 1
'type' => string 'varchar' (length=7)
'len' => int -1
'not null' => boolean false
'has default' => boolean true
'array dims' => int 0
'is enum' => boolean false
'is base' => boolean true
'is composite' => boolean false
'is pesudo' => boolean false
'description' => string '' (length=0)
'id' =>
array (
size=11)
'num' => int 2
'type' => string 'int4' (length=4)
'len' => int 4
'not null' => boolean true
'has default' => boolean true
'array dims' => int 0
'is enum' => boolean false
'is base' => boolean true
'is composite' => boolean false
'is pesudo' => boolean false
'description' => string '' (length=0)
?>
up
0
Hayley Watson
6 years ago
To specify a schema as well as a table name, use the "schemaname.tablename" form as usual for PostgreSQL and the other functions in this extension. Without the prefix, of course, the default schema search path is used.

<?php
$meta
= pg_meta_data($dbconn, 'foo.bar'); // table "bar" in schema "foo"
if (is_array($meta)) {
var_dump($meta);
}
?>
up
0
dmiller at NOSPAM dot judcom dot nsw dot gov dot au
21 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
18 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 ...
up
-4
jsnell at e-normous dot com
16 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;
}
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