NEWBIE to ORACLE SQL and I have a following situation:
Table X_1 (PRIMARY KEY A_1)
A_1,A_2,A_3,A_4
8998A,01/01/2014,XYXY,REST WELL
BHYXTY,04/20/2015,UUUU,PEACE
99999,02/06/2014,LLLL,FUN
TABLE X_2 (F_1 & F_2 PRIMARY KEY)
F_1,F_2,F_3,F_4,A_2,A_3,A_4
8998A,0,TEST,XXX,NULL,XYXY,NULL...