Reg Internal table modification based on other itab

Hi Folks,

    I have two internal tables, my first internal table as follows(this is final internla table i want to modify this based on other itab)

material  field1 field2   newfield

  mat1    aa     bb     

  mat2   xx     yy

my second internal table has

mat                ref mat

mat1              A1

mat1              A2

mat1              A3

mat2             B2

mat2             B3

my final internal table is 1st one I want my new output as

material  field1 field2   newfield

  mat1    aa     bb         A1

  mat1    aa     bb         A2

  mat1    aa     bb         A3

  mat2   xx     yy         B2

  mat2   xx     yy         B3

Please give me some input how can i achieve the above.

Thanks,

Smriti