PHP: sqlite_fetch_single

Описание

string sqlite_fetch_single ( resource result [, bool decode_binary] )

sqlite_fetch_single() идентична sqlite_fetch_array() за исключением того, что возвращается значение только первого поля.

Использование этой функции является оптимальным способом получения данных, когда нужно получить значение только одного поля.

Пример 1. Пример использования sqlite_fetch_single()

<?php if ($dbhandle = sqlite_open('mysqlitedb', 0666, $sqliteerror)) { $sql = "SELECT id FROM sometable WHERE id = 42"; $res = sqlite_query($dbhandle, $sql); if (sqlite_num_rows($res) > 0) { echo sqlite_fetch_single($res); // 42 } sqlite_close($dbhandle); } ?>

sqlite_fetch_single

jmarbas at hotmail dot com
23-Jul-2005 05:45


It isnt specified in the above description for this function, but yes this function will not only return the first column, but it will also return the first value (ie from the first row in the result set) of that column. Also the result set pointer is involved here in that if you use sqlite_fetch_single in a loop, it will return each value in the first column sequentially and advance the result set pointer each time.



i.e. the first loop iteration it returns the first value in the first column. the second loop iteration it returns the second value in the first column. the third loop iteration the third value and so on.



  $handle = sqlite_open("database_file_name") or die("Could not open database");

  //generate query string

  $query = "select distinct field1 from database_name";

  //execute query

  $result = sqlite_query($handle,$query)

  //if a row exists

  if(sqlite_num_rows($result)>0){

    echo "<table cellpadding=\"10\" border=\"1\">";

    //check for more rows

    while(sqlite_has_more($result)){

      //get first field from each row

      //print values

      $row=sqlite_fetch_single($result);

      echo "<tr>";

      echo "<td>".$row."</td>";

      echo "</tr>";

    }

    echo "</table>";

  }

  //close database file

  sqlite_close($handle);

roga at yoopee dot de
11-Jul-2004 01:02


Be careful with the use of sqlite_fetch_single() in a while-loop:



<?php

$result = sqlite_query($db_handle, 'SELECT foo FROM bar;');



while ($row = sqlite_fetch_single($result)) {

     /*...do s.th. with $row...*/

}

?>



This may not work as expected because the loop will stop if any of the foos has a false value (e.g. zero).



Use sqlite_has_more() instead:



<?php

$result = sqlite_query($db_handle, 'SELECT foo FROM bar;');



while (sqlite_has_more($result)) {

     $row = sqlite_fetch_single($result);

     /*...do s.th. with $row...*/

}

?>

sqlite_fetch_single

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