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
Opis
Styl obiektowy
mysqli::select_db
( string
$dbname
) : boolStyl proceduralny
Selects the default database to be used when performing queries against the database connection.
Informacja:
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().
Parametry
-
połączenie -
Tylko styl proceduralny: Identyfikator połączenia zwrócony przez mysqli_connect() lub mysqli_init()
-
dbname -
The database name.
Zwracane wartości
Zwraca TRUE w przypadku powodzenia, FALSE w
przypadku błędu.
Przykłady
Przykład #1 mysqli::select_db() example
Styl obiektowy
<?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();
?>
Styl proceduralny
<?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);
?>
Powyższe przykłady wyświetlą:
Default database is test. Default database is world.
Zobacz też:
- mysqli_connect() - Alias dla 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.
