Creating condition specific view

     I want to create one view which will be condition specific. Below are the details.

  I have 2 SQL queries If data is available in  Query 1  then fetch data else fetch data from   Query 2.

 

Query 1.       

select acs.config_setting_name,ccs.config_setting_value from admin_config_settings

 acs , cust_config_settings  ccs where acs.config_settings_id = ccs.config_setting_id

 and acs.config_settings_id = '1000' and ccs.customer_id='1000';

 

If no row selected with this above query then get result from below query else display result from Query 1

 Query 2 . 

select config_setting_name,config_setting_default_value from admin_config_settings