To be able to debug external application, which uses RFC functions, you have to use external degugging. Sometime, this external breakpoint does not work.
If so, firstly start RSRTRACE transaction, and now the breakpoint will work.
QD uses class CL_RSZA_QUERY and its methods.
Method that loads the query -> LOAD_QUERY (FM that loads the query element or query itself: RSZ_X_COMPONENT_GET )
Method that saves the query -> SAVE_QUERY (FM that saves the query element or query itself RSZ_X_COMPONENT_SET_NEW )
QD – Query designer
BEx – Business Explorer