PHP mysqli select_db() 函数

示例 - 面向对象风格

更改连接的默认数据库：

<?php
$mysqli = new mysqli("localhost","my_user","my_password","my_db");

if ($mysqli -> connect_errno) {
echo "Failed to connect to MySQL: " . $mysqli -> connect_error;
exit();
}

// Return name of current default database
if ($result = $mysqli -> query("SELECT DATABASE()")) {
$row = $result -> fetch_row();
echo "Default database is " . $row[0];
$result -> close();
}

// Change db to "test" db
$mysqli -> select_db("test");

// Return name of current default database
if ($result = $mysqli -> query("SELECT DATABASE()")) {
$row = $result -> fetch_row();
echo "Default database is " . $row[0];
$result -> close();
}

$mysqli -> close();
?>

查看底部的程序样式示例。

定义和用法

select_db() / mysqli_select_db() 函数用于更改连接的默认数据库。

语法

面向对象风格：

$mysqli -> select_db( name)

程序风格：

mysqli_select_db( connection, name)

参数值

Parameter	Description
connection	Required. Specifies the MySQL connection to use
name	Required. Specifies the database name

技术细节

返回值：	成功则为真。失败时为 FALSE
PHP 版本：	5+

示例 - 程序风格

更改连接的默认数据库：

<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");

if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
exit;
}

// Return name of current default database
if ($result = mysqli_query($con, "SELECT DATABASE()")) {
$row = mysqli_fetch_row($result);
echo "Default database is " . $row[0];
mysqli_free_result($result);
}

// Change db to "test" db
mysqli_select_db($con, "test");

// Return name of current default database
if ($result = mysqli_query($con, "SELECT DATABASE()")) {
$row = mysqli_fetch_row($result);
echo "Default database is " . $row[0];
mysqli_free_result($result);
}

// Close connection
mysqli_close($con);
?>

❮ PHP MySQLi 参考