pg_fetch_assoc

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

pg_fetch_assoc获取一行作为关联数组

说明

pg_fetch_assoc(PgSql\Result $result, ?int $row = null): array|false

pg_fetch_assoc() 返回与所提取的行(元组/记录)相一致的关联数组。

pg_fetch_assoc() 等同于调用 PGSQL_ASSOC 作为第三个参数的 pg_fetch_array()。其仅返回关联数组。如果需要数字索引,使用 pg_fetch_row()

注意: 此函数将 NULL 字段设置为 PHP null 值。

使用 pg_fetch_assoc() 并不比 pg_fetch_row() 慢的明显,而且在使用中提供了更大的方便。

参数

result

PgSql\Result 实例,由 pg_query()pg_query_params() 或者 pg_execute()(等)返回。

row

要获取的结果中的行号。行从 0 向上编号。如果省略或为 null,则获取下一行。

返回值

关联方式(按字段名)的 arrayarray 中的每个值都表示为 string。数据库 NULL 值作为 null 返回。

如果 row 超过集合中的行数、没有更多行或任何其他错误,则返回 false。从 SELECT 以外的查询结果中获取也将返回 false

更新日志

版本 说明
8.1.0 现在 result 参数接受 PgSql\Result 实例,之前接受 resource

示例

示例 #1 pg_fetch_assoc() 示例

<?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'];
}
?>

参见

add a note

User Contributed Notes 17 notes

up
13
slurppp at hotmail dot fr
11 years ago
Note that all pg_fetch_* function ignoring the original type of the data and always return strings. (for numbers too)
up
3
Anonymous
14 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.
up
6
Luke
18 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"
up
2
Anonymous
17 years ago
If you request a row that does not exist, it just fails, rather than simply returning false.
up
1
ninja (whorl) thinkninja (stop) com
20 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);
}
}
up
0
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;
}
}
}

}
up
0
huntfalow at yahoo dot com
8 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>
up
0
Alexey Loktionov (error at pochta dot ru)
13 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;
}

?>
up
0
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');

?>
up
0
Anonymous
15 years ago
bytea columns are returned escaped.
you need to call pg-unescape-bytea() on them to get the original binary back.
up
0
Anonymous
15 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.
up
0
javier dot vilarroig at gmail dot com
16 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.
up
0
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>';

?>
up
0
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.
up
0
spam at pasher dot org
20 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.
up
0
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.
up
-3
strata_ranger at hotmail dot com
15 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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