PHP Oracle Errors with Double quotes?

I'm new to Oracle and am trying to pull information from Oracle into a web page.

PHP Version 5.2.1
Apache 2.0.55

When I just do a basic query the results return fine but when I use double quotes in my php to I can include a WHERE statment I start getting errors
here are 2 examples of the code i'm using:

Works But can't use a WHERE statment:
$db_conn = ocilogon("xxxxxx", "xxxxxx", "xxxxxx");
$cmdstr = 'select app_user from application$_user';

$parsed = ociparse($db_conn, $cmdstr);
ociexecute($parsed);

Doesn't work with Double Quotes in the query:
$db_conn = ocilogon("xxxxxx", "xxxxxx", "xxxxxxx");
$cmdstr = "select app_user from application$_user where app_user = 'BLAH'";

$parsed = ociparse($db_conn, $cmdstr);
ociexecute($parsed);


Any help would be greatly appreciated.



-

here is a copy of the error

Warning: ociexecute() [function.ociexecute]: ORA-00942: table or view does not exist in C:\Program Files\Apache Group\Apache2\htdocs\opera\myconnectiontest7.php on line 7

$cmdstr = 'select app_user from application$_user where app_user = ''BLAH''';

Thanks for the responce.. I tried the query but php is barking at me for it.
$cmdstr = 'select app_user from application$_user where = "BLAH"';

Error:
Warning: ociexecute() [function.ociexecute]: ORA-00904: "BLAH": invalid identifier in C:\Program Files\Apache Group\Apache2\htdocs\opera\myconnectiontest7.php on line 7

Warning: ocifetchstatement() [function.ocifetchstatement]: ORA-24374: define not done before fetch or execute and fetch in C:\Program Files\Apache Group\Apache2\htdocs\opera\myconnectiontest7.php on line 9

This is so confusing I know I should be able to use double quotes and it works fine with Sql, I wonder if it is maybe a configuration change that needs to be done in php.ini??

problems solved.

I had to change (application$_user)
$blah = 'application$_user';
$cmdstr = "select app_user from $blah where(app_user LIKE '%$search%')";