File 1:123, 234345, 789678, 900File 2123, abc345, dncoutput (all columns in file1 and missing value in file two as NA):123,234,abc345,789,dnc678,900,NAOutput file  add with another file File 3123, 2014/10/20678, 2013/02/30Output file123,234,abc,2014/10/20345,789,dnc,NA678,900,NA,2013/02/30There are such 10 files which I need to add to the 1st file
Need to compare the two files and print all the columns then missing display as NA, then join another file
text processing;awk;scripting;join