PDOStatement::getColumnMeta

(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo >= 0.2.0)

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

Descrizione

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

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

Avviso

Some drivers may not implement PDOStatement::getColumnMeta(), as it is optional. However, all PDO drivers documented in the manual implement this function.

Elenco dei parametri

column: The 0-indexed column in the result set.

Valori restituiti

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.

Esempi

Example #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);
?>

Il precedente esempio visualizzerà:

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

Vedere anche:

PDOStatement::columnCount() - Returns the number of columns in the result set
PDOStatement::rowCount() - Returns the number of rows affected by the last SQL statement

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User Contributed Notes 7 notes

down

colin at fusionbox dot com ¶

15 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.

down

asohn aircanopy net ¶

16 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.

down

samer dot mhana at gmail dot com ¶

3 years ago


Searching for LONGLONG in php-src: 
    
$datatypes = array(
        MYSQLI_TYPE_TINY => "TINY",
        MYSQLI_TYPE_SHORT => "SHORT",
        MYSQLI_TYPE_LONG => "LONG",
        MYSQLI_TYPE_FLOAT => "FLOAT",
        MYSQLI_TYPE_DOUBLE => "DOUBLE",
        MYSQLI_TYPE_TIMESTAMP => "TIMESTAMP",
        MYSQLI_TYPE_LONGLONG => "LONGLONG",
        MYSQLI_TYPE_INT24 => "INT24",
        MYSQLI_TYPE_DATE => "DATE",
        MYSQLI_TYPE_TIME => "TIME",
        MYSQLI_TYPE_DATETIME => "DATETIME",
        MYSQLI_TYPE_YEAR => "YEAR",
        MYSQLI_TYPE_ENUM => "ENUM",
        MYSQLI_TYPE_SET    => "SET",
        MYSQLI_TYPE_TINY_BLOB => "TINYBLOB",
        MYSQLI_TYPE_MEDIUM_BLOB => "MEDIUMBLOB",
        MYSQLI_TYPE_LONG_BLOB => "LONGBLOB",
        MYSQLI_TYPE_BLOB => "BLOB",
        MYSQLI_TYPE_VAR_STRING => "VAR_STRING",
        MYSQLI_TYPE_STRING => "STRING",
        MYSQLI_TYPE_NULL => "NULL",
        MYSQLI_TYPE_NEWDATE => "NEWDATE",
        MYSQLI_TYPE_INTERVAL => "INTERVAL",
        MYSQLI_TYPE_GEOMETRY => "GEOMETRY",
    );

down

frankno dot 94 at gmail dot com ¶

5 years 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;
}
?>

down

Rodrigo Silva ¶

5 years 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()

down

-1

jcastromail at yahoo dot es ¶

4 years ago


This method is supported by sql server too (at least the version of the PDO driver 5.7.1)

Example:

array(8) {
  ["flags"]=>
  int(0)
  ["sqlsrv:decl_type"]=>
  string(12) "int identity"
  ["native_type"]=>
  string(6) "string"
  ["table"]=>
  string(0) ""
  ["pdo_type"]=>
  int(2)
  ["name"]=>
  string(8) "IdCompra"
  ["len"]=>
  int(10)
  ["precision"]=>
  int(0)
}

down

-10

frankno dot 94 at gmail dot com ¶

5 years 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.

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