If you want to export your apex application from database not from application, you can execute the below command
"SELECT APEX_050100.WWV_FLOW_EXPORT_API.GET_APPLICATION (your application id) d FROM DUAL"
some times your application server is not working but your DB server is ok and you need to export your application right now, then you need this function to export your application.
N.B
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this function work on 5.1.4 or later version
"SELECT APEX_050100.WWV_FLOW_EXPORT_API.GET_APPLICATION (your application id) d FROM DUAL"
some times your application server is not working but your DB server is ok and you need to export your application right now, then you need this function to export your application.
N.B
-------
this function work on 5.1.4 or later version