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    mysql_data_seek

    (PHP 4, PHP 5)

    mysql_data_seek — 내부 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()는 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
    20 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
    12 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
    19 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
    19 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
    16 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
    18 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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