mysqli::select_db

mysqli_select_db

(PHP 5, PHP 7, PHP 8)

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

Descrizione

Stile orientato agli oggetti

public mysqli::select_db(string $database): bool

Stile procedurale

mysqli_select_db(mysqli $mysql, string $database): bool

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

Nota:

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().

Elenco dei parametri

link

Solo nello stile procedurale: un identificatore restituito da mysqli_connect() o mysqli_init()

database

The database name.

Valori restituiti

Restituisce true in caso di successo, false in caso di fallimento.

Esempi

Example #1 mysqli::select_db() example

Stile orientato agli oggetti

<?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]);

Stile procedurale

<?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]);

I precedenti esempi visualizzeranno:

Default database is test.
Default database is world.

Vedere anche:

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User Contributed Notes 2 notes

up
-9
hwalker1 at btopenworld dot com
8 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
-21
pjasiulewicz at gmail dot com
11 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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