pg_fetch_assoc

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

pg_fetch_assoc — Fetch a row as an associative array

Descrierea

pg_fetch_assoc ( resource $result , int $row = ? ) : array

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().

Notă: Această funcție stabilește câmpurile NULL la valoarea PHP null.

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

Parametri

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 or null, the next row is fetched.

Valorile întoarse

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.

Exemple

Example #1 pg_fetch_assoc() example


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

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

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

A se vedea și

pg_fetch_row() - Get a row as an enumerated array
pg_fetch_array() - Fetch a row as an array
pg_fetch_object() - Fetch a row as an object
pg_fetch_result() - Returns values from a result resource

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User Contributed Notes 17 notes

down

slurppp at hotmail dot fr ¶

12 years ago


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

down

Luke ¶

19 years ago


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"

down

Anonymous ¶

18 years ago


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

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ninja (whorl) thinkninja (stop) com ¶

21 years ago


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);
    }
}

down

Anonymous ¶

15 years ago


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.

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artem.eroshin gmail com ¶

4 years ago


Converts 't' and 'f' to PHP Boolean

$result = pg_query($_db, $sql);

while ( $row = pg_fetch_assoc( $result ) )
{
    fixBooleans($result, $row);

    //some other code
}

function fixBooleans($result, &$row)
{

    for ($fld_i = 0; $fld_i < pg_num_fields($result); $fld_i++)
    {
        $fld_name = pg_field_name($result, $fld_i);

        if( pg_field_type($result, $fld_i) == 'bool' )
        {
            if( $row[ $fld_name ] == 't' )
            {
                $row[ $fld_name ] = true;
            }
            elseif($row[ $fld_name ] == 'f')
            {
                $row[ $fld_name ] = false;
            }
        }
    }

}

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huntfalow at yahoo dot com ¶

9 years ago


<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>Remediëringsoefening</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>

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Alexey Loktionov (error at pochta dot ru) ¶

14 years ago


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;
    }

?>

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Anonymous ¶

14 years ago


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');

?>

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Anonymous ¶

16 years ago


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

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Anonymous ¶

16 years ago


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.

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javier dot vilarroig at gmail dot com ¶

17 years ago


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.

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johniskew ¶

17 years ago


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>';

?>

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petrus at bmail dot com dot au ¶

19 years ago


$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.

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spam at pasher dot org ¶

21 years ago


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.

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Brenton Strickler ¶

21 years ago


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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-3

strata_ranger at hotmail dot com ¶

16 years ago


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)
?>

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