pg_query

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_query — Führt eine Abfrage aus

Beschreibung

pg_query ( resource $connection = ? , string $query ) : resource|false

pg_query() führt die query auf der angegebenen Datenbank-Verbindung connection aus. In der Regel sollte pg_query_params() bevorzugt werden.

Falls ein Fehler auftritt und false zurückgegeben wird, können Sie Details zu diesem Fehler mit pg_last_error() anzeigen, vorausgesetzt, die Verbindungskennung ist gültig.

Hinweis: Obwohl der Parameter connection weggelassen werden kann, ist dies nicht empfehlenswert, da es die Fehlersuche in Skripten erschweren kann.

Hinweis:
Diese Funktion ersetzt die Funktion pg_exec(). pg_exec() wird aus Gründen der Kompatibilität immer noch unterstützt, es wird jedoch empfohlen, den neuen Funktionsnamen zu verwenden.

Parameter-Liste

connection: Die PostgreSQL-Verbindungskennung. Falls connection nicht angegeben wurde, wird die zuletzt mit pg_connect() oder pg_pconnect() geöffnete Verbindung benutzt.
query: Die auszuführende(n) SQL-Anweisung(en). Werden mehrere Anweisungen an pg_query() übergeben, werden sie automatisch in einer einzigen Transaktion ausgeführt, es sei denn, die Anweisungsfolge enthält explizite BEGIN/COMMIT-Anweisungen. Von der Ausführung mehrerer Transaktionen innerhalb eines Funktionsaufrufs wird abgeraten.

Warnung
String-Interpolation von Anwenderdaten ist sehr gefährlich, und führt wahrscheinlich zu SQL-Injection-Sicherheistlücken. In der Regel sollte pg_query_params() bevorzugt werden, wobei Anwenderdaten als Parameter übergeben werden anstatt sie in der Abfragezeichenkette zu ersetzen.

Jegliche Anwenderdaten, die direkt in eine Abfragezeichenkette interpoliert werden, sollten ordnungsgemäß maskiert werden.

Rückgabewerte

Bei Erfolg wird eine Ergebniskennung für die Abfrage zurückgegeben. Im Fehlerfall wird false zurückgegeben.

Beispiele

Beispiel #1 pg_query()-Beispiel


<?php

$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
  echo "Ein Fehler ist aufgetreten.\n";
  exit;
}

$result = pg_query($conn, "SELECT author, email FROM authors");
if (!$result) {
  echo "Ein Fehler ist aufgetreten.\n";
  exit;
}

while ($row = pg_fetch_row($result)) {
  echo "Autor: $row[0]  E-Mail: $row[1]";
  echo "<br />\n";
}

?>

Beispiel #2 pg_query() mit mehreren Anweisungen


<?php

$conn = pg_pconnect("dbname=publisher");

// diese Anweisungen werden in einer einzigen Transaktion ausgeführt.

$query = "UPDATE authors SET author=UPPER(author) WHERE id=1;";
$query .= "UPDATE authors SET author=LOWER(author) WHERE id=2;";
$query .= "UPDATE authors SET author=NULL WHERE id=3;";

pg_query($conn, $query);

?>

Siehe auch

pg_connect() - Öffnet eine PostgreSQL-Verbindung
pg_pconnect() - Öffnet eine persistente PostgreSQL-Verbindung
pg_fetch_array() - Liefert eine Zeile als Array
pg_fetch_object() - Liefert einen Datensatz als Objekt
pg_num_rows() - Gibt die Anzahl der Zeilen in einem Abfrageergebnis zurück
pg_affected_rows() - Gibt die Anzahl betroffener Datensätze (Tupel) zurück

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User Contributed Notes 15 notes

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a dot mcruer at live dot com ¶

10 years ago


A quick note for novice users: when gathering input from fields on a web form that maintains a database connection, *never* use pg_query to do queries from the field. Always sanitize input using pg_prepare and pg_execute.

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hierophantNOSPAM at pcisys dot net ¶

21 years ago


Regarding david.bouriaud@ac-rouen.fr:
You misunderstand SQL. When a query is issued, results applicable at the time of the query are returned to the application (i.e. PHP). There is no further reference to the database required. Thus, all of the pg_fetch_* functions are acting on an internal data storage, NOT the database itself. This is because SQL does not have a concept of sets, or of state (except in limited circumstances provided by transactions). However, if you use a cursor instead, fetching only one record at a time, you may get an error if you delete the table. If you don't, it is an issue with Postgres, not PHP.

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Jan-Willem Regeer ¶

18 years ago


In reply to david dot bouriaud at ac-rouen dot fr:

All it is doing is internal caching. How can that be dangerous. If you are going to be deleting records after you have closed the connection it is your problem to make sure you have the latest and greatest records, and not some cached ones. Considering you are writing the script I don't see why it is a problem, you know what you are doing in the script, so it is quite useless for PHP to invalidate the cache, when that could be done upon exiting the script, which would mean there was less time spent cleaning out the cache when it counts most (when returning data to the user).

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jsuzuki at spamcop dot net ¶

18 years ago


expanding on the note left by "cmoore" -

To check to see if the recordset returned no records,

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "query did not execute";
  }
  $rs = pg_fetch_assoc($result);
  if (!$rs) {
    echo "0 records"
  }
?>

-jack

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zoli at makettinfo.hu ¶

17 years ago


It would be better this way:

<?php
  $result=pg_query($conn, "SELECT COUNT(*) AS rows FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if ($line = pg_fetch_assoc($result)) {
    if ($line['rows'] == 0) {
     echo "0 records"
    }
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?> 

This solution doesn't raise the load of the system with the move of matching rows (perhaps 0,1, perhaps 100, 1000, ... rows)

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mankyd ¶

17 years ago


There was a typo in the code that I posted:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
   while ($row = pg_fetch_array($result)) {
     //do stuff with $row
   }
  }
?>

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cmoore ¶

18 years ago


One thing to note that wasn't obvious to me at first.  If your query returns zero rows, that is not a "failed" query.  So the following is wrong:
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
    echo "No a=b in x\n";
  }

pg_query returns FALSE if the query can not be executed for some reason.  If the query is executed but returns zero rows then you get back a resul with no rows.

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mankyd ¶

17 years ago


Improving upon what jsuzuki said:

It's probably better to use pg_num_rows() to see if no rows were returned, as that leaves the resultset cursor pointed to the first row so you can use it in a loop.

Example:

<?php
  $result=pg_query($conn, "SELECT * FROM x WHERE a=b;");
  if  (!$result) {
   echo "query did not execute";
  }
  if (pg_num_rows($result) == 0) {
   echo "0 records"
  }
  else {
    while ($row = pg_fetch_array($result) {
      //do stuff with $row
    }
  }
?>

I, personally, also find it more readable.

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mentat at azsoft dot pl ¶

21 years ago


$GLOBALS["PG_CONNECT"]=pg_connect(...);
....

function query ($sqlQuery,$var=0) {
   if (!$GLOBALS["PG_CONNECT"]) return 0;
   $lev=error_reporting (8); //NO WARRING!!
   $result=pg_query ($sqlQuery);
   error_reporting ($lev); //DEFAULT!!
   if (strlen ($r=pg_last_error ($GLOBALS["PG_CONNECT"]))) {
      if ($var) {
        echo "<p color=\"red\">ERROR:<pre>";
        echo $sqlQuery;
        echo "</pre>";
        echo $r;
        echo "&lt/p>";
      }
      close_db ();
      return 0;
   }
   return $result;
}

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-1

Anonymous ¶

10 years ago


Here is my small function to make it easier for me to use data from select queries (attention, it is sensitive to sql injection)
<?php
function requestToDB($connection,$request){ 
    if(!$result=pg_query($connection,$request)){
        return False;
    }
    $combined=array();
    while ($row = pg_fetch_assoc($result)) {
        $combined[]=$row;
    }
    return $combined;
}
?>

Example:
<?php
$conn = pg_pconnect("dbname=mydatabase");

$results=requestToDB($connect,"select * from mytable");

//You can now access a "cell" of your table like this:
$rownumber=0;
$columname="mycolumn";

$mycell=$results[$rownumber][$columname];
var_dump($mycell);

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-2

Akbar ¶

19 years ago


Use pg_query to call your stored procedures, and use pg_fetch_result when getting a value (like a smallint as in this example) returned by your stored procedure.

<?php
$pgConnection = pg_connect("dbname=users user=me");

$userNameToCheckFor = "metal";

$result = pg_query($pgConnection, "SELECT howManyUsersHaveThisName('$userNameToCheckFor')");

$count = pg_fetch_result($result, 0, 'howManyUsersHaveThisName');
?>

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-3

david dot bouriaud at ac-rouen dot fr ¶

21 years ago


Hi to all !
It seems that the old pg_exec function does not do what it is expected to.
In the doc, it is said that it returns a resource identifier on the successful querry that was send to the backend.
It seems to me that it is more than a resource identifier.
Follow the example :

<?php
$ConnId = pg_connect ("blablabla");
$ResId = pg_exec ("select * from table", $ConnId);
pg_close ($ConnId);
$row = pg_fetch_array ($ResId, 4);
?>

I closed the connection voluntarily before the pg_fetch_array. It WORKS !

Now, imagine the following script :
<?php
$ConnId = pg_connect ("blablabla");
$ResId = pg_exec ("select * from table", $ConnId);
pg_close ($ConnId);
system ("psql base -c delete from table");
$row = pg_fetch_array ($ResId, 4);
?>
See how it could be harmful !!!! I think that the coders have done this for performances reasons, but it is not the right way do do so !!!

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-4

yoshinariatsuo at yahoo dot com ¶

21 years ago


create table from pg_query results.. hope it helps newbies...
function table_create($result)
{
    $numrows = pg_num_rows($result);
    $fnum = pg_num_fields($result);

    echo "<table border width='100%'>";
    echo "<tr>";

    for ($x = 0; $x < $fnum; $x++) {
        echo "<td><b>";
        echo strtoupper(pg_field_name($result, $x));
        echo "</b></td>";
    }

    echo "</tr>";

    for ($i = 0; $i < $numrows; $i++) {
        $row = pg_fetch_object($result, $i);
        echo "<tr align='center'>";
        for ($x = 0; $x < $fnum; $x++) {
    $fieldname = pg_field_name($result, $x);
    echo "<td>";
    echo $row->$fieldname;
    echo "</td>";
        }
        echo"</tr>";
    }
    echo "</table>";
    
    return 0;
}

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-5

sd at dicksonlife dot com ¶

17 years ago


Took me a while to track this down so I thought it might be useful for others:

If you use stored procedures and need to get result sets back from them:

function dbquery($link,$query){
  pg_query($link,"BEGIN;");
  $tr=pg_query($link,$query);
  $r=pg_fetch_row($tr);
  $name=$r[0];
  $rs=pg_query($link,"FETCH ALL IN \"" . $name . "\";");
  pg_query($link,"END;");
  return $rs;
}

(Error checking removed for clarity)

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-8

jvarner at dsrglobal dot com ¶

21 years ago


That's why your code should never assume it has the very latest data unless it locks it.

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