mysql_data_seek

(PHP 4, PHP 5)

mysql_data_seek내부 결과 포인터를 이동

설명

bool mysql_data_seek ( resource $result , int $row_number )

mysql_data_seek()는 result에 지정한 MySQL 결과의 내부 행 포인터를 지정한 행 번호로 옮깁니다. 다음으로 mysql_fetch_assoc() 등의 MySQL 페치 함수를 호출하면, 그 행이 반환됩니다.

row_number는 0부터 시작합니다. row_number는 0부터 mysql_num_rows() - 1까지의 값을 가질 수 있습니다. 그러나 결과셋이 비어 있고(mysql_num_rows() == 0), 0행을 탐색하면 E_WARNING을 발생하며 실패하고 mysql_data_seek()FALSE를 반환합니다.

인수

result

mysql_query() 호출을 통한 결과 resource.

row_number

새로운 결과 포인터의 행 번호를 필요로 한다.

반환값

성공 시 TRUE를, 실패 시 FALSE를 반환합니다.

예제

Example #1 mysql_data_seek() 예제

<?php
$link 
mysql_connect('localhost''mysql_user''mysql_password');
if (!
$link) {
    die(
'Could not connect: ' mysql_error());
}
$db_selected mysql_select_db('sample_db');
if (!
$db_selected) {
    die(
'Could not select database: ' mysql_error());
}
$query 'SELECT last_name, first_name FROM friends';
$result mysql_query($query);
if (!
$result) {
    die(
'Query failed: ' mysql_error());
}
/* fetch rows in reverse order */
for ($i mysql_num_rows($result) - 1$i >= 0$i--) {
    if (!
mysql_data_seek($result$i)) {
        echo 
"Cannot seek to row $i: " mysql_error() . "\n";
        continue;
    }

    if (!(
$row mysql_fetch_assoc($result))) {
        continue;
    }

    echo 
$row['last_name'] . ' ' $row['first_name'] . "<br />\n";
}

mysql_free_result($result);
?>

주의

Note:

mysql_data_seek() 함수는 mysql_query()와 함께 사용할 경우에는 사용할 수 있으나 , mysql_unbuffered_query()와는 함께 사용할 수 없다.

참고

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User Contributed Notes 6 notes

up
6
kennethnash1134 at yahoo dot com
16 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
3
saeed at photobookworldwide dot com
8 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
arturo_b at hotmail dot com
15 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
-2
b.steinbrink at g m x dot de
15 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
-4
Daniel
12 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
-5
Anonymous
14 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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