PHP PDO：SQL查询结束时的常量变量

Question

I can't seem to figure this one out, I'm trying to globalize all of the database credentials across my application , therefore I'm setting the database table name in a global constants file. I have one query that no matter how many ways I try to set the constant variable in the string, it fails miserably. Anyone have any ideas?

Here's the query before the constant variable change, which works:

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

Here's a few different attempts that all fail (the constant variable is 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");

I even tried to set it initially as a variable:

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

How can I fix this? Thanks!

Answer 1

常量后，您不需要“”。

"SELECT MAX(salesPosition) FROM " . TBL_NAVIGATION 

Answer 2

Always check your syntax is the lesson to be learned here:

The correct query was:

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

Thanks to Kaii for waking me up!