mysqli::select_db

mysqli_select_db

(PHP 5, PHP 7)

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

Opis

Styl obiektowy

mysqli::select_db ( string $dbname ) : bool

Styl proceduralny

mysqli_select_db ( mysqli $link , string $dbname ) : bool

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:

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User Contributed Notes 2 notes

up
-13
hwalker1 at btopenworld dot com
6 years 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.
up
-15
pjasiulewicz at gmail dot com
9 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.
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