選取工作資料庫

1. 連線到 mysql，必須選擇工作資料庫，否則每行指令都必須指明要處理的資料庫，比較麻煩，以文字命令列登入工作後，使用 use 命令選取要工作的資料庫為 dyw。
   

   [root@kvm8 html]# mysql -uroot -p
   Enter password: 
   Welcome to the MySQL monitor.  Commands end with ; or \g.
   Your MySQL connection id is 21
   Server version: 5.5.38 MySQL Community Server (GPL) by Remi
   
   Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
   
   Oracle is a registered trademark of Oracle Corporation and/or its
   affiliates. Other names may be trademarks of their respective
   owners.
   
   Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
   
   mysql> use dyw;
   Database changed
   mysql> show tables;
   Empty set (0.00 sec)
   
   mysql> exit
   Bye
   

2. 使用 php 函數 mysql_select 選取資料庫 dywphp。
   

   [root@kvm8 ~]# cd /var/www/html
   [root@kvm8 html]# vim selectdb.php
   [root@kvm8 html]# cat selectdb.php
   <html>
   <head>
   <title>Selecting MySQL Database</title>
   </head>
   <body>
   <?php
   $dbhost = 'localhost:3306';
   $dbuser = 'dywang';
   $dbpass = '123qwe';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   if(! $conn )
   {
     die('Could not connect: ' . mysql_error());
   }
   echo 'Connected successfully';
   mysql_select_db( 'dywphp' );
   mysql_close($conn);
   ?>
   </body>
   </html>
   

3. 以 php 命令執行 selectdb.php 選取 dywphp 資料庫，使用瀏覽器開啟 selectdb.php 也可以。
   

   [root@kvm8 html]# php selectdb.php
   <html>
   <head>
   <title>Selecting MySQL Database</title>
   </head>
   <body>
   Connected successfully</body>
   </html>