Oracle 5.0 Reference Manual page 2437

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.
Parameters
link
dbname
Return Values
Returns on success or
TRUE
Examples
Example 20.141.
mysqli::select_db
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();
}
MySQL Improved Extension (Mysqli)
Procedural style only: A link identifier returned by
mysqli_connect
The database name.
on failure.
FALSE
example
2417
or
mysqli_init