pg_fetch_object

pg_fetch_array

Last updated: Fri, 20 Nov 2009

pg_fetch_assoc

(PHP 4 >= 4.3.0, PHP 5)

pg_fetch_assoc — Fetch a row as an associative array

Description

array pg_fetch_assoc ( resource $result [, int $row ] )

pg_fetch_assoc() returns an associative array that corresponds to the fetched row (records).

pg_fetch_assoc() is equivalent to calling pg_fetch_array() with PGSQL_ASSOC as the optional third parameter. It only returns an associative array. If you need the numeric indices, use pg_fetch_row().

Note: This function sets NULL fields to the PHP NULL value.

pg_fetch_assoc() is NOT significantly slower than using pg_fetch_row(), and is significantly easier to use.

Parameters

result: PostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
row: Row number in result to fetch. Rows are numbered from 0 upwards. If omitted, next row is fetched.

Return Values

An array indexed associatively (by field name). Each value in the array is represented as a string. Database NULL values are returned as NULL.

FALSE is returned if row exceeds the number of rows in the set, there are no more rows, or on any other error.

Changelog

Version	Description
4.1.0	The parameter `row` became optional.

Examples

Example #1 pg_fetch_assoc() example


<?php 
$conn = pg_connect("dbname=publisher");
if (!$conn) {
  echo "An error occured.\n";
  exit;
}

$result = pg_query($conn, "SELECT id, author, email FROM authors");
if (!$result) {
  echo "An error occured.\n";
  exit;
}

while ($row = pg_fetch_assoc($result)) {
  echo $row['id'];
  echo $row['author'];
  echo $row['email'];
}
?>


Beware!  If your query returns multiple columns with the same names, only the right-most one will be contained in the result array.  This can cause problems if you are using a combination of joins:



For example:

<?php

// Let's say that 'pkey' is the primary-key colum for tables a and b (primary keys are never null)

$res = pg_query("Select a.pkey, b.* FROM a LEFT JOIN b using (pkey)");

$data = pg_fetch_assoc($res);

var_dump($data['pkey']) // Is actually b.pkey, may be NULL!

?>



Both tables contain a column named 'pkey'.  Now table 'b' is on the optional side of a LEFT JOIN, so b.pkey (implicitly included via 'b.*') may be NULL.



The problem arises when you use pg_fetch_assoc(), there are two columns named 'pkey' but the result array can only contain one value per key -- in this case it will pick the one from table B instead of the one from table A, and since B is on the optional side of the left-join, $data['pkey'] may be NULL.  So if you're expecting to retrieve the column from table A, you need to use a different pg_fetch() or rewrite your query to avoid ambiguity.

Anonymous
14-Oct-2008 12:18


bytea columns are returned escaped.

you need to call pg-unescape-bytea() on them to get the original binary back.

Anonymous
13-Oct-2008 11:03


regarding the optional int parameter



requesting a row number that is not present in the result set is an error. don't do it.



check with pg_num_rows() beforehand, or  just use the default behavior which returns the rows in order and false after returning the last row it returns false immediately if no rows were returned.

strata_ranger at hotmail dot com
26-Aug-2008 10:01


In a bit of follow-up to Luke's note about SQL booleans (this was a painful thing to learn the hard way), a relatively easy workaround is to typecase the boolean columns to integer inside the query, e.g:



<?php

// Assuming 'foo' is a table column of type boolean

$res = pg_query("Select foo as foo1, foo::integer as foo2 from bar");



$data = pg_fetch_assoc($res);

if ($data['foo1']) echo 'foo1 = TRUE'; // Doesn't work as expected (string 't' and string 'f' both evaluate as TRUE)

if ($data['foo2']) echo 'foo2 = TRUE'; // Works as expected (string '0' evaluates as FALSE)

?>

javier dot vilarroig at gmail dot com
02-Oct-2007 04:57


Is worth to know that when you query on multiple tables only the first row with each name is returned.



That is, if you are joining to tables with a column called 'name' you will receive only one field called name in the array and it will correspond to the one on the first table.



Is advisable to allways allias your columns in that stuation.

johniskew
01-Mar-2007 05:28


Here is another way to iterate a resultset and display all columns in very little code... might be faster than a foreach



<?php



print '<table>';

while($row=pg_fetch_assoc($rs2)) print '<tr><td>'.join('</td><td>',$row2).'</td></tr>';

print '</table>';



?>

24-May-2006 07:59


If you request a row that does not exist, it just fails, rather than simply returning false.

Luke
22-Sep-2005 01:34


Note:



PostgreSQL boolean values set to TRUE are returned as the string "t"



PostgreSQL boolean values set to FALSE are returned as the string "f"

petrus at bmail dot com dot au
25-Feb-2005 03:22


$dbconn3 = pg_connect("host=127.0.0.1 port=5432 dbname=blah user=blah password=blah");

$result = pg_query($dbconn3, "SELECT * FROM Packages");



 echo "<HTML><HEAD><TITLE>PostgreSQL Test Page</TITLE></HEAD><BODY>";

 echo "<TABLE>";



$pkg = pg_fetch_assoc($result);

foreach ($pkg as $value) {

    echo "<TR><TD>$value";

    echo "</TR></TD>";

 }



echo "</TABLE><P>";

echo "This package's full filename is: {$pkg['name']}-{$pkg['version']}{$pkg['extension']}";

echo "</BODY></HTML>";



For generating tables, this works, and personally I prefer foreach() to while loops because there's no danger of accidentally causing an infinite loop...foreach only works for as long as it has something to work with, and then stops.  I thought the echo down the bottom might come in handy, too...took me a bit to find that out.

spam at pasher dot org
25-Oct-2003 01:35


An important thing to note (as of PHP 4.3.2):



If you are used to using the "extended" comparision operators (=== and !==) to try to make your code easier to follow visually, this function will return NULL if the provided resource handle is invalid (as opposed to false). ie,



$rs = @pg_query('SELECT * FROM fake_table');

while (false !== ($row = @pg_fetch_assoc($rs)))

{

    print_r($row);

}



Obviously you should check to see if $rs === false before you start the while loop, but this example is used to illustrate a potential infinite loop problem if $rs IS false.

ninja (whorl) thinkninja (stop) com
21-Jun-2003 03:29


If you are moving between different versions of PHP, this might be handy:



if (!function_exists('pg_fetch_assoc')) {

    function pg_fetch_assoc ($result)

    {

      return @pg_fetch_array($result, NULL, PGSQL_ASSOC);

    }

}

Brenton Strickler
07-Jan-2003 01:53


At a glance, the syntax listed at the top of this page doesn't match the example.  The PGSQL_ASSOC flag isn't necessary.

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