pg_fetch_assoc

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

pg_fetch_assoc — 提取一行作为关联数组

说明

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

pg_fetch_assoc() 和调用 pg_fetch_array() 加上第三个可选参数 PGSQL_ASSOC 是等价的。它只返回一个关联数组。如果需要数字索引，用 pg_fetch_row()。

pg_fetch_assoc() 是 pg_fetch_row() 的扩展版本。除了将数据存储在数字索引（字段编号）之外，默认还将数组存储在关联索引（字段名）中。

row 是要被提取的行（记录）编号。第一行为 0。

pg_fetch_assoc() 并不明显比 pg_fetch_row() 慢，而且还显著更便于使用。

Example #1 pg_fetch_assoc() 例子


<?php
$conn = pg_pconnect("dbname=publisher");
if (!$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'];
}
?>

参见 pg_fetch_row()，pg_fetch_array()，pg_fetch_object() 和 pg_fetch_result()。

User Contributed Notes

huntfalow at yahoo dot com 24-Apr-2015 05:46


<html>

<head>

<script>

function waarde(){

    var text = document.getElementById("optVakken").value;

    document.getElementById("txthidden").value = text;

    document.forms["hiddenform"].submit();

}

</script>

<?php

// keuzemenu met alle leerkrachten

function leerkrachten($aName){

    include("includes/connect.php");

    

}

// keuzemenu met alle vakken

function vakken($aID){

    include("includes/connect.php");

    $SelectVakkenQuery = "SELECT * FROM vakken";

    $SelectVakkenResult = $mysqli->query($SelectVakkenQuery);

    $Choice = "<select id='$aID' onchange=waarde()><option>Kies een vak</option>";

    

        while($rij2 = $SelectVakkenResult->fetch_assoc()){

        $VakID = $rij2['vakid'];

        $Vaknaam = $rij2['voluit'];

        $Choice .= "<option value='$VakID'>$Vaknaam</option>";

    }

    $Choice .= "</select>";

    return $Choice;

}

?>

<title>Remedi?ringsoefening</title>

</head>

<body>

<?php

include("includes/connect.php");

// aanmaken van keuzemenus



// eerste keuzemenu

echo vakken("optVakken")."<br><br>";



// tweede keuzemenu

if(!isset($_POST['txthidden'])){

$SelectLeerkrachtenQuery = "SELECT * FROM leerkrachten";

$SelectLeerkrachtResult = $mysqli->query($SelectLeerkrachtenQuery);

    

$Choice = "<select>";

while($rij=$SelectLeerkrachtResult->fetch_assoc()){

    $Voornaam = $rij['voornaam'];

    $Naam = $rij['naam'];

    $LKID = $rij['leerkrachtid'];

    $Volledig = $Voornaam . " " . $Naam;

    $Choice .= "<option value='$LKID'>$Volledig</option>";

}

$Choice .= "</select><br><br>";

echo $Choice;

}else{

    $vakid = $_POST['txthidden'];

    $SelectLeerkrachtenQuery = "SELECT * FROM leerkrachten JOIN leerkrachtpervak ON leerkrachten.leerkrachtid = leerkrachtpervak.leerkrachtid WHERE vakid = '$vakid'";

    $SelectLeerkrachtResult = $mysqli->query($SelectLeerkrachtenQuery);

    $Choice = "<select>";

    while($row3=$SelectLeerkrachtResult->fetch_assoc()){

        $Voornaam = $row3['voornaam'];

        $Naam = $row3['naam'];

        $Volledig = $Voornaam . " " . $Naam;

        $Choice .= "<option>$Volledig</option>";

    }

    $Choice .= "</select><br><br>";

    echo $Choice;

}

// onzichtbaar textbox voor JS

echo "<form method='post' id='hiddenform'><input type='hidden' name='txthidden' id='txthidden'></form>";

$mysqli->close();

?>

</body>

</html>

slurppp at hotmail dot fr 08-Jun-2012 11:37


Note that all pg_fetch_* function ignoring the original type of the data and always return strings. (for numbers too)

Alexey Loktionov (error at pochta dot ru) 10-Mar-2010 01:54


Here is much powerful pg_parse_array() variant, based on FSM: for any dimension Postgres arrays (its string representation must be well-formed), with quotation rules checks, complexity O(N), where N is a length of string representation of Postgres array:



<?php



define('STATE_BEGIN', 1);

define('STATE_INARRAY',2);

define('STATE_OUTARRAY', 3);

define('STATE_INSLASH', 4);

define('STATE_INQUOTES', 5);



function pg_parse_array($value) {

        $resultArray = $indexArray = array(); $level = $index = 0;

        $ptr = &$resultArray;

        for($i = 0; $i < strlen($value); $i++){

            switch($level){

                case 1:

                    if($index > 0){

                        $ptr = & $ptr[sizeof($ptr)];

                    }

                    $indexArray[++$index] = & $ptr;

                    break;

                case -1:

                    $ptr = & $indexArray[--$index];

                    break;

            }

            $level = processFSM($value{$i}, $ptr);

        }

        return $resultArray;

    }

    

    function processFSM($chr, &$result){

        static $state = STATE_BEGIN, $index = 0;

        $level = 0;

        switch(true){

            case $chr == '{' && in_array($state, array(STATE_BEGIN,STATE_INARRAY,STATE_OUTARRAY), true):

                $state = STATE_INARRAY;

                $index = 0;

                $level = +1;

                break;

            case $chr == '}' && in_array($state, array(STATE_INARRAY,STATE_OUTARRAY), true):

                $state = STATE_OUTARRAY;

                $level = -1;

                break;

            case $chr == '\\' && $state !== STATE_BEGIN:

                $state = $state === STATE_INSLASH ? STATE_INQUOTES : STATE_INSLASH;

                break;

            

            case $chr == '"' && !in_array($state, array(STATE_BEGIN,STATE_INSLASH), true):

                $state = $state === STATE_INQUOTES ? STATE_INARRAY : STATE_INQUOTES;

                break;

            

            case $chr == ',' && in_array($state, array(STATE_INARRAY,STATE_OUTARRAY), true):

                $index = sizeof($result);

                break;

            

            case $state !== STATE_BEGIN:

                $state = $state === STATE_INSLASH ? STATE_INQUOTES : $state;

                isset($result[$index]) or $result[$index] = '';

                $result[$index] .= $chr;

                break;

        }

        return $level;

    }



?>

Anonymous 16-Jan-2010 12:16


Be aware that if one of your result fields is an array, it will be output as a string using the general format of '{value1,value2, ... }' in accordance with postgres's behavior with SQL arrays.

http://www.postgresql.org/docs/8.4/static/arrays.html#ARRAYS-IO



So, here is a function to convert simple (one-dimensional) SQL arrays to PHP arrays:



<?php

function pg_parse_array($field)

/*

 * Converts a simple SQL array field to its PHP equivalent.  e.g:

 *

 *    {null}              --> Array(null);

 *    {"null"}            --> Array("null");

 *    {foo,bar}           --> Array("foo", "bar"); 

 *    {"foo,bar"}         --> Array("foo,bar");

 *    {"Hello \"World\""} --> Array('Hello "World"');

 *       

 */  

{

  // NULL fields are always NULL

  if (!is_string($field)) return $field;



  // Check for curly braces which may indicate an SQL array field

  if ($field[0] != '{' or substr($field, -1) != '}') return $field;

  $field = trim(substr($field, 1, -1));



  $array = Array();

  

  // Break up the string into the following:

  //  - quoted text that MAY have special chars escaped by a backslash

  //  - unquoted text that may NOT have special chars

  $search = '/(")?+((?(1)(?:\\\\.|[^"])*|[^,]+))(?(1)\\1)/';

  preg_match_all($search, $field, $matches, PREG_SET_ORDER);

  

  foreach($matches as $value)

  {

    if ($value[1])

    {

      // Quoted element, with backslash used to escape chars

      $array[] = preg_replace('#\\\\(.)#', '$1', $value[2]);

    }

    else

    {

      // Unquoted element

      $value[2] = trim($value[2]);

      if (strtolower($value[2]) == 'null') $array[] = null; // NULL

      else $array[] = $value[2];

    }  

  }

  return $array;

}



// Some tests to demonstrate this function

var_export(pg_parse_array('{null}'); // Output is Array(null);

var_export(pg_parse_array('{foo,bar}'); // Output is Array('foo', 'bar');

var_export(pg_parse_array('{"null"}'); // Output is Array('null');



?>

Anonymous 19-May-2009 05:24


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 02:18


bytea columns are returned escaped.

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

Anonymous 14-Oct-2008 01:03


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 27-Aug-2008 12:01


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 06:57


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 06:28


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 09:59


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

Luke 22-Sep-2005 03:34


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 04:22


$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 03:35


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 05:29


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 02:53


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