SunshinePHP Developer Conference 2015

mysqli::select_db

mysqli_select_db

(PHP 5)

mysqli::select_db -- mysqli_select_dbSelects the default database for database queries

Beschreibung

Objektorientierter Stil

bool mysqli::select_db ( string $dbname )

Prozeduraler Stil

bool mysqli_select_db ( mysqli $link , string $dbname )

Selects the default database to be used when performing queries against the database connection.

Hinweis:

This function should only be used to change the default database for the connection. You can select the default database with 4th parameter in mysqli_connect().

Parameter-Liste

link

Nur bei prozeduralem Aufruf: Ein von mysqli_connect() oder mysqli_init() zurückgegebenes Verbindungsobjekt.

dbname

The database name.

Rückgabewerte

Gibt bei Erfolg TRUE zurück. Im Fehlerfall wird FALSE zurückgegeben.

Beispiele

Beispiel #1 mysqli::select_db() example

Objektorientierter Stil

<?php
$mysqli 
= new mysqli("localhost""my_user""my_password""test");

/* check connection */
if (mysqli_connect_errno()) {
    
printf("Connect failed: %s\n"mysqli_connect_error());
    exit();
}

/* return name of current default database */
if ($result $mysqli->query("SELECT DATABASE()")) {
    
$row $result->fetch_row();
    
printf("Default database is %s.\n"$row[0]);
    
$result->close();
}

/* change db to world db */
$mysqli->select_db("world");

/* return name of current default database */
if ($result $mysqli->query("SELECT DATABASE()")) {
    
$row $result->fetch_row();
    
printf("Default database is %s.\n"$row[0]);
    
$result->close();
}

$mysqli->close();
?>

Prozeduraler Stil

<?php
$link 
mysqli_connect("localhost""my_user""my_password""test");

/* check connection */
if (mysqli_connect_errno()) {
    
printf("Connect failed: %s\n"mysqli_connect_error());
    exit();
}

/* return name of current default database */
if ($result mysqli_query($link"SELECT DATABASE()")) {
    
$row mysqli_fetch_row($result);
    
printf("Default database is %s.\n"$row[0]);
    
mysqli_free_result($result);
}

/* change db to world db */
mysqli_select_db($link"world");

/* return name of current default database */
if ($result mysqli_query($link"SELECT DATABASE()")) {
    
$row mysqli_fetch_row($result);
    
printf("Default database is %s.\n"$row[0]);
    
mysqli_free_result($result);
}

mysqli_close($link);
?>

Die obigen Bespiele erzeugen folgende Ausgabe:

Default database is test.
Default database is world.

Siehe auch

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User Contributed Notes 2 notes

up
-1
pjasiulewicz at gmail dot com
3 years ago
In some situations its useful to use this function for changing databases in general. We've tested it in production environment and it seams to be faster with switching databases than creating new connections.
up
-1
hwalker1 at btopenworld dot com
9 months ago
Note that in the second example, if the database "world" does not exist, the database selected does not change. You may need to add additional code to ensure that you are connected to the correct database.
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