我创建了一个名为“class.admin.php”的类，它进行了一些检查。我有一个调用类的文件，该类在尝试选择数据库时工作正常。
当我运行时，mysql_select_db() or die我收到错误“未选择数据库”。
类.admin.php
class admin {
### Function that check for the connect file (if it exists)
public function checkConnector() {
if(file_exists(CONN)) { return true; } else { return false; }
}
### Check connection to MYSQL
public function checkConnection() {
global $cn; if(mysql_connect()) { return true; } else { return false; }
}
### Check connection to database
public function checkDB() {
global $db; if(mysql_select_db()) { return true; } else { return false; }
}
索引.php
$admin = new admin();
# Check the connect file exists
if($admin->checkConnector() === true) {
# Check connection to MYSQL server
if($admin->checkConnection() === true) {
### Check selection of DB
if($admin->checkDB() === true) {
print 'Selection of database is fine.';
} else {
print 'Selection of database is not working.';
}
} else {
print '<p>I\'m sorry, could not connect to MYSQL.</p>';
};
} else {
print '<p>I\'m sorry the connection file does not exist. Please install accordingly.</p>';
}