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)
mysqli::select_db -- mysqli_select_db — Selects the default database for database queries
Beskrivelse
Object oriented style
bool mysqli::select_db
( string
$dbname
)Procedural style
Selects the default database to be used when performing queries against the database connection.
Note:
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().
Parametre
-
link -
Procedural style only: A link identifier returned by mysqli_connect() or mysqli_init()
-
dbname -
The database name.
Returnerings Værdier
Returns TRUE on success or FALSE on failure.
Eksempler
Eksempel #1 mysqli::select_db() example
Object oriented style
<?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();
?>
Procedural style
<?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);
?>
The above examples will output:
Default database is test. Default database is world.
Se også
- mysqli_connect() - Alias af 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.
