PHP PDO : Constant Variable at End of SQL Query

Question

我似乎无法弄清楚这一点，我正在尝试将我的应用程序中的所有数据库凭据全局化，因此我在全局常量文件中设置数据库表名。我有一个疑问，无论我尝试用多少种方法在字符串中设置常量变量，它都会惨败。有人有主意吗？

这是常量变量更改之前的查询，它有效:

$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM crmManager");

这里有几个不同的尝试都失败了(常量变量是 TBL_NAVIGATION):

$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM " . TBL_NAVIGATION . ");    
$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM".TBL_NAVIGATION.");
$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM".TBL_NAVIGATION);
$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM {TBL_NAVIGATION}");
$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM".TBL_NAVIGATION");

我什至试图将它最初设置为一个变量:

$table = TBL_NAVIGATION;
$stmt = $dbh->prepare("SELECT MAX(salesPosition) FROM {table}"); 
 // I've tried every possible way to include the variable

我该如何解决这个问题？谢谢!

Answer 1

常量后不需要 "。

"SELECT MAX(salesPosition) FROM " . TBL_NAVIGATION