mysql_data_seek

(PHP 4, PHP 5)

mysql_data_seekMuove il puntatore interno del risultato

Descrizione

bool mysql_data_seek ( resource $identificativo_risultato , int $numero_riga )

Restituisce TRUE in caso di successo, FALSE in caso di fallimento.

mysql_data_seek() muove il puntatore di riga interno del risultato MySQL associato all'identificativo specificato per puntare ad un determinato numero di riga. La successiva chiamata a mysql_fetch_row() dovrebbe restituire questa riga.

numero_riga inizia da 0. numero_riga dovrebbe essere un valore nell'intervallo che va da 0 a mysql_num_rows - 1.

Nota:

La funzione mysql_data_seek() può essere usata solo insieme a mysql_query(), non con mysql_unbuffered_query().

Example #1 Esempio seek dati MySQL

<?php
    $connessione 
mysql_pconnect("localhost""utente_mysql""password_mysql")
        or die(
"Connessione non riuscita: " mysql_error());

    
mysql_select_db("samp_db")
        or die(
"Selezione del database non riuscita: " mysql_error());

    
$query "SELECT cognome, nome FROM amici";
    
$risultato mysql_query($query)
        or die(
"Query fallita: " mysql_error());

    
/* caricamento righe in ordine inverso */
    
for ($i mysql_num_rows($risultato) - 1$i >= 0$i--) {
        if (!
mysql_data_seek($risultato$i)) {
            echo 
"Non si può eseguire il seek alla riga $i: " mysql_error() . "\n";
            continue;
        }

        if(!(
$riga mysql_fetch_object($risultato)))
            continue;

        echo 
"$riga->cognome $riga->nome<br />\n";
    }

    
mysql_free_result($risultato);
?>

Vedere anche: mysql_query(), mysql_num_rows().

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User Contributed Notes 6 notes

up
0
Daniel
5 years ago
Here is a simple function to "peek" at the position of the internal pointer in a query result:

<?php
function mysql_pointer_position($result_set) {
       
$num_rows = mysql_num_rows($result_set);
       
$i = 0;
        while(
$result = mysql_fetch_array($result_set)) {
           
$i++;
        }
       
$pointer_position = $num_rows - $i;

//Return pointer to original position
       
if($pointer_position <= $num_rows - 1) {
           
mysql_data_seek($result_set, $pointer_position);
        }
        return
$pointer_position;
    }
?>
up
0
arturo_b at hotmail dot com
9 years ago
hello, this script would be easy to understand for those that are novice in php whose want to understand about this function:

the table "user" have 2 columns "id" and "name".
"user" content:
position 0: "id"=195342481 "name"='Arthur'
position 1: "id"=179154675 "name"='John'
>>position 2<<: "id"=157761949 "name"='April' >>third row<<
position 3: "id"=124492684 "name"='Tammy'
position 4: "id"=191346457 "name"='Mike'

<?php
  mysql_connect
("localhost", "root")
 
mysql_select_db("test");
 
$sql = mysql_query("select * from user");
 
mysql_data_seek($sql, 2);
  echo
"<table border=1>";
  while (
$row = mysql_fetch_row($sql)){
    echo
"<tr><td>$row[0]</td><td>$row[1]</td></tr>";
  }
  echo
"</tabla>";
?>

explanation:
mysql_data_seek move internal result pointer to the third row of table user. Thus mysql_fetch_row will begin by aprils row.
up
0
b.steinbrink at g m x dot de
9 years ago
to kennethnash1134 at yahoo dot com

your loop can be done like this as well and i guess this is faster:

$r=mysql_query("select user,id,ip from accounts limit 10");

unset($users); // Just to be sure
while($users[] = mysql_fetch_row);
array_pop($users); // Drop the last entry which is FALSE
up
0
kennethnash1134 at yahoo dot com
10 years ago
/*here is a nice function for converting a mysql result row set into a 2d array, a time saver if need small data from several rows, saves you from having to do Alot of queries... would be nice to have this built into PHP future versions :) */

// simple example query
$r=mysql_query("select user,id,ip from accounts limit 10");

//starts the for loop, using mysql_num_rows() to count total
//amount of rows returned by $r
for($i=0; $i<mysql_num_rows($r); $i++){
             //advances the row in the mysql resource $r
    mysql_data_seek($r,$i);
             //assigns the array keys, $users[row][field]
    $users[$i]=mysql_fetch_row($r);
}

//simple, hope someone can use it :)
// -Kenneth Nash
up
-1
saeed at photobookworldwide dot com
2 years ago
Here, you can find the current pointer of selected row easily:

<?php
//selected row with id=4
$id    =    "4";

$result    =    mysql_query("select * from jos_components");

$num    =    mysql_num_rows($result);

for(
$i=0;$i<$num;$i++){
   
   
mysql_data_seek($result,$i);
 
   
$row    =    mysql_fetch_assoc($result);
   
    if(
$row['id']    ==    $id){
       
       
$pointer    =    $i;
    }

 
}

// current pointer for selected row
echo $pointer;
?>
up
-2
Anonymous
7 years ago
A helpful note about the 'resource' data type.

Since the 'resource' variable is pointing to a row in a result set at any given time, you can think of it as being passed to this function by reference every time you pass it or assign it to a variable.

<?

$sql
= "SELECT * from <table>";
$result = mysql_query($sql);
$temp_result = $result;

while (
$row = mysql_fetch_assoc($temp_result)) {
   
// do stuff with $row
}

while (
$row = mysql_fetch_assoc($result)) {
   
// This code will never run because the 'resource' variable is pointing past the end of the result set,
    // even though it was *not* assigned by reference to $result2.
}

?>

Therefore, the following snipits are functionally identical:

<?

// Start snipit 1

$sql = "SELECT * from <table>";
$result = mysql_query($sql);

while (
$row = mysql_fetch_assoc($result)) {
   
// do stuff with $row
}

mysql_data_seek($result, 0);

while (
$row = mysql_fetch_assoc($result)) {
   
// do other stuff with $row
}

// Start snipit 2

$sql = "SELECT * from <table>";
$result = mysql_query($sql);
$temp_result = $result;

while (
$row = mysql_fetch_assoc($temp_result)) {
   
// do stuff with $row
}

mysql_data_seek($result, 0);

while (
$row = mysql_fetch_assoc($temp_result)) {
   
// do other stuff with $row
}

?>
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