Php/func mysqli select db

PHP mysqli select_db（）函数

MySQL PHP MySQLi参考

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();

?>

在底部查看程序样式的示例。

定义和用法

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

句法

面向对象的样式：

$mysqli -> 
  select_db(name)

程序风格：

mysqli_select_db(connection, name)

参数值

参数	描述
connection	需要。指定要使用的MySQL连接
name	需要。指定数据库名称

技术细节

返回值：	成功则为真。失败时为假
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);
?>

MySQL PHP MySQLi参考