pg_query

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

pg_query — Esegue una query

Descrizione

pg_query(resource $connessione, string $query): resource

pg_query() restituisce un risorsa risultato della query se è stato possibile eseguire quest'ultima. Retituisce false in caso di errore o se la connessione non è valida. I dettagli dell'errore si possono recuperare utilizzando la funzione pg_last_error() se la connessione è valida. pg_last_error() invia un comando SQL al database PostgreSQL specificato dalla risorsa connessione. Il parametro connessione deve essere una connessione valida restituita da pg_connect() o pg_pconnect(). Il valore di ritorno di questa funzione è una risorsa risultato che si può usare per accedere ai dati attraverso altre funzioni PostgreSQL come pg_fetch_array().

Nota: connessione è un parametro opzionale di pg_query(). Se connessione non è impostato, viene utilizzata la connessione di default, ovvero l'ultima connessione effettuata con pg_connect() o pg_pconnect(). Anche se connessione può essere omessa, ciò non è raccomandato, dal momento che questo può essere fonte di errori difficili da trovare nello script.

Nota:
Questa funzione si chiamava pg_exec(). pg_exec() è ancora disponibile, per ragioni di compatibilità, ma si consiglia agli utenti di usare il nuovo nome.

Vedere anche pg_connect(), pg_pconnect(), pg_fetch_array(), pg_fetch_object(), pg_num_rows() e pg_affected_rows().

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User Contributed Notes 9 notes

down

mentat at azsoft dot pl ¶

23 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;
}

down

a dot mcruer at live dot com ¶

12 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.

down

jsuzuki at spamcop dot net ¶

19 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

down

zoli at makettinfo.hu ¶

19 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)

down

cmoore ¶

20 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.

down

mankyd ¶

19 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
   }
  }
?>

down

-1

Akbar ¶

20 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');
?>

down

-2

mankyd ¶

19 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.

down

-2

Anonymous ¶

11 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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