select_db

❮ PHP MySQLi 参考手册

示例 - 面向对象的样式

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。

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定义和用法

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

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语法

面向对象的风格:

$mysqli -> select_db(name)

程序风格:

mysqli_select_db(connection, name)

参数值

参数	描述
connection	必需。规定要使用的 MySQL 连接。
name	必需，规定要使用的默认数据库。

技术细节

返回值:	若成功则返回 TRUE，若失败则返回 FALSE。
PHP 版本:	5+

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示例 - 程序样式

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);
?>

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❮ PHP MySQLi 参考手册