sqlite_fetch_single

SQLiteResult::fetchSingle

SQLiteUnbuffered::fetchSingle

(PHP 5 < 5.4.0, PECL sqlite >= 1.0.1)

sqlite_fetch_single -- SQLiteResult::fetchSingle -- SQLiteUnbuffered::fetchSingleRecupera la primera columna de un conjunto de resultados como cadena

Descripción

string sqlite_fetch_single ( resource $result [, bool $decode_binary = true ] )

Estilo orientado a objetos (método):

string SQLiteResult::fetchSingle ([ bool $decode_binary = true ] )
string SQLiteUnbuffered::fetchSingle ([ bool $decode_binary = true ] )

sqlite_fetch_single() es idéntica a sqlite_fetch_array() excepto que devuelve el valor de la primera columna del conjunto de filas.

Esta es la manera más óptima para recuperar datos cuando sólo interesan los valores de una única columna de datos.

Parámetros

result

El recurso de resultados de SQLite. Este parámetro no es necesario cuando se usa el método orientado a objetos.

decode_binary

Cuando el parámetro decode_binary es seteado a TRUE (el valor por defecto), PHP decodificará la codificación binaria que se aplicó a los datos si éstos fueron codificados usando la función sqlite_escape_string(). Normalmente debería dejar este valor por defecto, a menos que esté interoperando con bases de datos creadas por otras aplicaciones sqlite.

Valores devueltos

Devuelve el valor de la primera columna, como cadena.

Ejemplos

Ejemplo #1 Un ejemplo de 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);
}
?>

Ver también

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User Contributed Notes 3 notes

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1
jmarbas at hotmail dot com
8 years ago
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);
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0
visavi dot net at mail dot ru (Vantuz)
4 years ago
With the help of sqlite_fetch_single, you can quickly and easily calculate the number of elements in the table

<?php

// create new database (OO interface)
$db = new SQLiteDatabase('database.db', 0666);

// create table inbox and paste data
$db->queryExec("
CREATE TABLE inbox (
inbox_id INTEGER NOT NULL PRIMARY KEY,
inbox_send varchar(20) NOT NULL,
inbox_text TEXT NOT NULL,
inbox_time INTEGER UNSIGNED NOT NULL,
inbox_user varchar(20) NOT NULL
);"
);

$ins_query = "
INSERT INTO inbox (inbox_send, inbox_text, inbox_time, inbox_user) VALUES ('Ilia1', 'Message1', '"
.time()."', 'my_name');
INSERT INTO inbox (inbox_send, inbox_text, inbox_time, inbox_user) VALUES ('Ilia2', 'Message2', '"
.time()."', 'user');
INSERT INTO inbox (inbox_send, inbox_text, inbox_time, inbox_user) VALUES ('Ilia2', 'Message3', '"
.time()."', 'my_name');
"
;

$db->queryExec($ins_query);

//view all posts by my_name
$total = $db->singleQuery("SELECT count(*) FROM inbox WHERE inbox_user='my_name';");

echo
$total;
// the result will be the number 2

/* P.S. sorry for my english */
?>
up
0
roga at yoopee dot de
9 years ago
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...*/
}
?>
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