

            rdint (1) --- intersect two identical relations          07/01/82


          | _U_s_a_g_e

          |      rdint


          | _D_e_s_c_r_i_p_t_i_o_n

          |      'Rdint'  is  part  of  the  toy relational data base system,
          |      'rdb'.  It creates a new relation by performing  the  inter-
          |      section  of the two relations specified as standard inputs 1
          |      and 2 and writes the new  relation  on  standard  output  1.
          |      Both  relations  must  have  identical  descriptions  -- the
          |      domains must be identical and in the same order.

          |      The intersection creates a new relation containing  all  the
          |      rows which appear in both sets -- all other rows are discar-
          |      ded.   Identical  rows  are  not  removed from the resulting
          |      relation.  These  can  be  removed  by  using  'rdsort'  and
          |      'rduniq'.
          |      
          |           For example:
          |      
          |             p1.rel  --------------  p2.rel --------------
          |                     |code | name |         |code | name |
          |                     --------------         --------------
          |                     | 100 | pens |         | 100 | pens |
          |                     |-----|------|         |-----|------|
          |                     | 101 | ink  |         | 105 | ruler|
          |                     --------------         --------------
          |      
          |             p1.rel> p2.rel> rdint >p.rel
          |      
          |                           p.rel --------------
          |                                 |code | name |
          |                                 --------------
          |                                 | 100 | pens |
          |                                 --------------
          |      

          |      The  input relations must be files containing relations that
          |      were created by 'rdmake' or other 'rdb' programs;  relations
          |      cannot  be  read  from the terminal.  The output relation is
          |      displayed in a readable format if standard output is  direc-
          |      ted to a terminal; otherwise, the output relation is written
          |      in  binary  internal  format  for  processing by other 'rdb'
          |      programs.


          | _E_x_a_m_p_l_e_s

          |      p1.rel> p2.rel> rdint >p.rel
          |      p1.rel> p2.rel> rdint | rdsort | rduniq | rdprint






            rdint (1)                     - 1 -                     rdint (1)




            rdint (1) --- intersect two identical relations          07/01/82


          | _M_e_s_s_a_g_e_s

          |      "Sorry, a relation can't be read from the terminal"
          |      "relation is corrupted!!"
          |      "Can't access input relation 1"
          |      "Can't access input relation 2"
          |      "Relations must have identical descriptions"


          | _S_e_e _A_l_s_o

          |      rdcat (1), rdextr (1), rdjoin (1), rdmake (1), rdprint  (1),
          |      rdproj  (1),  rdsel  (1), rdsort (1), rduniq (1), rdatt (1),
          |      rdavg (1), rdcount (1), rddiff (1), rddiv  (1),  rdmax  (1),
          |      rdmin (1), rdnat (1), rdsum (1)











































            rdint (1)                     - 2 -                     rdint (1)


