PHP Australia Conference 2015

sqlite_fetch_single

SQLiteResult::fetchSingle

SQLiteUnbuffered::fetchSingle

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

sqlite_fetch_single -- SQLiteResult::fetchSingle -- SQLiteUnbuffered::fetchSingleFetches the first column of a result set as a string

Descrierea

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

Stil obiect-orientat (method):

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

sqlite_fetch_single() is identical to sqlite_fetch_array() except that it returns the value of the first column of the rowset.

This is the most optimal way to retrieve data when you are only interested in the values from a single column of data.

Parametri

result

The SQLite result resource. This parameter is not required when using the object-oriented method.

decode_binary

Când parametrul decode_binary este stabilit în TRUE (implicit), PHP va decodifica codificarea binară pe care a aplicat-o asupra datelor, dacă acestea au fost codificate cu sqlite_escape_string (). În mod normal ar trebui să lăsați valoarea implicită, dacă nu interoperați cu baze de date create de alte aplicații capabile să lucreze cu sqlite.

Valorile întoarse

Returns the first column value, as a string.

Exemple

Example #1 A sqlite_fetch_single() example

<?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);
}
?>

Vedeți de asemenea

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User Contributed Notes 3 notes

up
1
jmarbas at hotmail dot com
9 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);
up
0
visavi dot net at mail dot ru (Vantuz)
5 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
10 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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