PDOStatement::getColumnMeta

(PHP 5 >= 5.1.0, PHP 7, PECL pdo >= 0.2.0)

PDOStatement::getColumnMeta Returns metadata for a column in a result set

Beschreibung

public PDOStatement::getColumnMeta ( int $column ) : array

Retrieves the metadata for a 0-indexed column in a result set as an associative array.

Warnung

Not all PDO drivers support PDOStatement::getColumnMeta().

The following drivers support this method:

Parameter-Liste

column

The 0-indexed column in the result set.

R├╝ckgabewerte

Returns an associative array containing the following values representing the metadata for a single column:

Column metadata
Name Value
native_type The PHP native type used to represent the column value.
driver:decl_type The SQL type used to represent the column value in the database. If the column in the result set is the result of a function, this value is not returned by PDOStatement::getColumnMeta().
flags Any flags set for this column.
name The name of this column as returned by the database.
table The name of this column's table as returned by the database.
len The length of this column. Normally -1 for types other than floating point decimals.
precision The numeric precision of this column. Normally 0 for types other than floating point decimals.
pdo_type The type of this column as represented by the PDO::PARAM_* constants.

Returns FALSE if the requested column does not exist in the result set, or if no result set exists.

Changelog

Version Beschreibung
5.4.0 PDO_DBLIB driver support added
5.2.3 table field

Beispiele

Beispiel #1 Retrieving column metadata

The following example shows the results of retrieving the metadata for a single column generated by a function (COUNT) in a PDO_SQLITE driver.

<?php
$select 
$DB->query('SELECT COUNT(*) FROM fruit');
$meta $select->getColumnMeta(0);
var_dump($meta);
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

array(6) {
  ["native_type"]=>
  string(7) "integer"
  ["flags"]=>
  array(0) {
  }
  ["name"]=>
  string(8) "COUNT(*)"
  ["len"]=>
  int(-1)
  ["precision"]=>
  int(0)
  ["pdo_type"]=>
  int(2)
}

Siehe auch

add a note add a note

User Contributed Notes 5 notes

up
10
colin at fusionbox dot com
10 years ago
This method is supported in the MySQL 5.0+ driver.  It can be used for object hydration:

<?php

$pdo_stmt
= $dbh->execute('SELECT discussion.id, discussion.text, comment.id, comment.text FROM discussions LEFT JOIN comments ON comment.discussion_id = discussion.id');

foreach(
range(0, $pdo_stmt->columnCount() - 1) as $column_index)
{
 
$meta[] = $pdo_stmt->getColumnMeta($column_index);
}

while(
$row = $pdo_stmt->fetch(PDO::FETCH_NUM))
{
  foreach(
$row as $column_index => $column_value)
  {
   
//do something with the data, using the ids to establish the discussion.has_many(comments) relationship.
 
}
}

?>

If you are building an ORM, this method is very useful to support more natural SQL syntax.  Most ORMs require the column names to be aliases so that they can be parsed and turned into objects that properly represent has_one, has_many, many_to_many relationships.
up
3
asohn aircanopy net
11 years ago
I found a short discussion related to this function at
http://www.sitepoint.com/forums/showthread.php?t=497257

I haven't tried it (yet?) but hopefully someone can find it useful.
up
1
Rodrigo Silva
1 month ago
native_type has the following mapping for MySQL:
(tested in PHP 5.4, MySQL 5.7)

INT(11) (PKs) => LONG
TINYINT(4)    => TINY
DOUBLE        => DOUBLE
VARCHAR       => VAR_STRING
CHAR          => STRING
DATE          => DATE
Functions     => VAR_STRING
- DATEFORMAT()
- CONCAT()
up
0
frankno dot 94 at gmail dot com
1 month ago
I recently added a note to a small function that went through the results of PDOStatement::fetch and mapped columns to integer or float types.

I forgot to test for columns that can have a null value!

I'm updating the code here, sorry.

This website doesn't let me edit the original comment, so I'm just gonna link to a gist in case it needs even further fixes.

https://gist.github.com/AeonFr/db3b2a8a95753076d9e4da42d29365d2

I basically added this code:

<?php
if ($value === null) {
   continue;
}
?>
up
-1
frankno dot 94 at gmail dot com
1 month ago
I was able to successfully pull off basic type conversion for integer and float values in PDO.

NULL values were returning as null, but integers and floats weren't, so I decided to go with a simple solution.

It's not tested on all database types, so if you think it needs improvement, let me know (my twitter is "francanobr")

<?php

// Returns the contents of $stm (PDO Statement)
// as an associative array, with correct native types
// for integers, nulls, and floats

$array = [];

while (
$fila = $stm->fetch(\PDO::FETCH_ASSOC)) {

   
$i = 0;
    foreach (
$fila as $key => $value) {
       
$columnMeta = $stm->getColumnMeta($i);

        switch (
$columnMeta['native_type']) {
            case
'LONG':
            case
'TINY':
               
$fila[$key] = intval($value);
                break;
            case
'DOUBLE':
               
$fila[$key] = floatval($value);
                break;
        }

       
$i++;
    }

   
$array[] = $fila;
}

return
$array;
?>

The code sample is part of a function, the function declaration is not included, evaluate how to integrate it with your app.
To Top