how to do comparison with read statement

hi all,

i got 2 internal table with the following data.

i_tab_a

-

matnr budat

mat1 20080608

mat1 20080601

i_tab_b

-

matnr charg budat flag

mat1 a 20080606 X

mat1 b 20080606

mat1 c 20060606

mat1 d 20060605

mat1 e 20060605

loop i_tab_a

read table i_tab_b with key mat1 = i_tab_a-matnr

budat < i_tab_a-budat (??)

flag = ''.

endloop.

after the first read, the 1st record at i_tab_b will be marked as read.

my question is how to get the second record of i_tab_a to match with the 4th record of the i_tab_b, without hte budat < i_tab_a-budat in the read statement? any alternative can do the same thing?

thanks.