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.
mysqli::select_db
mysqli_select_db
(PHP 5, PHP 7)
mysqli::select_db -- mysqli_select_db — Selects the default database for database queries
Beschreibung
Objektorientierter Stil
public mysqli::select_db
( string
$database
) : boolProzeduraler Stil
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.
-
database -
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_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");
/* get the name of the current default database */
$result = $mysqli->query("SELECT DATABASE()");
$row = $result->fetch_row();
printf("Default database is %s.\n", $row[0]);
/* change default database to "world" */
$mysqli->select_db("world");
/* get the name of the current default database */
$result = $mysqli->query("SELECT DATABASE()");
$row = $result->fetch_row();
printf("Default database is %s.\n", $row[0]);
Prozeduraler Stil
<?php
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$link = mysqli_connect("localhost", "my_user", "my_password", "test");
/* get the name of the current default database */
$result = mysqli_query($link, "SELECT DATABASE()");
$row = mysqli_fetch_row($result);
printf("Default database is %s.\n", $row[0]);
/* change default database to "world" */
mysqli_select_db($link, "world");
/* get the name of the current default database */
$result = mysqli_query($link, "SELECT DATABASE()");
$row = mysqli_fetch_row($result);
printf("Default database is %s.\n", $row[0]);
Die obigen Bespiele erzeugen folgende Ausgabe:
Default database is test. Default database is world.
Siehe auch
- mysqli_connect() - Alias von mysqli::__construct
- mysqli_real_connect() - Opens a connection to a mysql server
add a note
User Contributed Notes 2 notes
hwalker1 at btopenworld dot com ¶
10 years ago
pjasiulewicz at gmail dot com ¶
13 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.
