Projection is used to vertically filter and select columns in a table.The Selection operation can be used to filter rows that satisfy a certain condition in a table.
program learn implicit none integer,dimension(2,3)::a integer,dimension(2,3)::b integer,dimension(24)::c integer,dimension(4,6)::d integer::i,j integer::k a=reshape([1,2,66,89,74,79],[2,3],order=[1,2]) b=reshape([1,2,76,99,84,59],[2,3],order=[1,2]) write (*,120) 'aid','a1','a2','bid','b1','b2' c=[((a(i,:),b(j,:),i=1,2),j=1,2)] d=reshape(c,[4,6],order=[2,1]) write (*,110) c write (*,*) "---------" write (*,110) d(2,:) write (*,*) "---------" write (*,110) d(:,2) write (*,*) "---------" write (*,*) "b1>70 and a2<70" write (*,120) 'aid','a1','a2','bid','b1','b2' !b1>70 and a2<90 Selection k=1 do if (d(k,5)>70 .and. d(k,3)<79) write (*,110) d(k,:) k=k+1 if (k>4) exit end do write (*,120) 'aid','a1','a2','bid','b1','b2' !b1>70 and a2<90 Projection and Selection write (*,*) "b1>70 and a2<70 and aid=bid" write (*,120) 'aid','a1','a2','b1','b2' k=1 do if (d(k,5)>70 .and. d(k,3)<79 .and. d(k,1)==d(k,4)) write (*,110) d(k,1:3),d(k,5:6) k=k+1 if (k>4) exit end do 110 format (6(I3)) 120 format (6(A3)) end program learn 
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