Salesforce JOIN query issues, How to work JOIN in Salesforce : Salesforce below my JOIN query not work,, so please help me

$query = "SELECT s__c.Id,s__c.mobile_number__c,s__c.student_id__c,s__c.user_id__c,s__c.student_name__c FROM student__c AS s__c INNER JOIN uraan_db__c AS u__c ON u__c.Id=s__c.user_id__c ";


Error:=

Fatal error: Uncaught SoapFault exception: [sf:MALFORMED_QUERY] MALFORMED_QUERY: s__c.student_name__c FROM student__c AS s__c INNER JOIN uraan_db__c AS u__c ON ^ ERROR at Row:1:Column:118 unexpected token: 'INNER' in /opt/lampp/htdocs/ashvin/portal/soapclient/SforceBaseClient.php:799 Stack trace: #0 /opt/lampp/htdocs/ashvin/portal/soapclient/SforceBaseClient.php(799): SoapClient->__call('query', Array) #1 /opt/lampp/htdocs/ashvin/portal/soapclient/SforceBaseClient.php(799): SforceSoapClient->query(Array) #2 /opt/lampp/htdocs/ashvin/portal/student_list.php(24): SforceBaseClient->query('SELECT s__c.Id,...') #3 {main} thrown in /opt/lampp/htdocs/ashvin/portal/soapclient/SforceBaseClient.php on line 799