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pg_query

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

pg_queryEsegue 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().

add a note

User Contributed Notes 10 notes

up
5
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)
up
5
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
up
4
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.
up
3
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;
}
up
1
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.
up
1
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
}
}
?>
up
-1
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.
up
-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');
?>
up
-2
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);
up
-8
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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