How to run queries on-demand instance.. we can't install phpmyadmin or phpminiadmin.php , is there any front end can be installed and use?

Just a thought, and probably overkill, but since you only have access to the DB through the application, and you are only wanting to query the system - not modify it - you could maybe build yourself a custom API

http://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_8.0/Integration/Web_Services/REST_API/Ex… 

that runs the query you need using a

SugarQuery

http://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_7.9/Data_Framework/Database/SugarQuery/i… 

or Prepared Statement

Use of prepared statements in Sugar 7.9 

FrancescaS

Just a thought, and probably overkill, but since you only have access to the DB through the application, and you are only wanting to query the system - not modify it - you could maybe build yourself a custom API

http://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_8.0/Integration/Web_Services/REST_API/Ex… 

that runs the query you need using a

SugarQuery

http://support.sugarcrm.com/Documentation/Sugar_Developer/Sugar_Developer_Guide_7.9/Data_Framework/Database/SugarQuery/i… 

or Prepared Statement

Use of prepared statements in Sugar 7.9 

FrancescaS