无法从数据库中选择列,已定义常量

Question

当我尝试从数据库中选择数据库时,我遇到了问题.

我正在使用此代码:

include($_SERVER['DOCUMENT_ROOT'].'/central/inc/db.php');
$SQLSelect = $odb -> query("SELECT * FROM `status_testadores` ORDER BY `ID` DESC");
while ($show = $SQLSelect -> fetch(PDO::FETCH_ASSOC))
{ 
    $rowID = $show['ID'];
    $sv1_db = $show['server_1']; 
}

它会返回以下错误:

Notice: Constant DB_HOST already defined in /Applications/MAMP/htdocs/central/inc/db.php on line 2
Notice: Constant DB_NAME already defined in /Applications/MAMP/htdocs/central/inc/db.php on line 3
Notice: Constant DB_USERNAME already defined in /Applications/MAMP/htdocs/central/inc/db.php on line 4
Notice: Constant DB_PASSWORD already defined in /Applications/MAMP/htdocs/central/inc/db.php on line 5

它正在发生,因为我必须在标题上包含db.php(与sql db建立连接的文件),但现在我需要它包含在我的侧边栏上,将数据库数据显示在其中,有没有办法可以连接没有这些错误的数据库？

Answer 1

您应该使用include_once而不是include,因为您的文件定义常量应该只包含一次.

将您的代码更改为:

include_once($_SERVER['DOCUMENT_ROOT'].'/central/inc/db.php');
$SQLSelect = $odb -> query("SELECT * FROM `status_testadores` ORDER BY `ID` DESC");
while ($show = $SQLSelect -> fetch(PDO::FETCH_ASSOC))
{ 
    $rowID = $show['ID'];
    $sv1_db = $show['server_1']; 
}