rdcount (1) --- count the number of rows in a relation   07/01/82


          | _U_s_a_g_e

          |      rdcount [<selection expr>]


          | _D_e_s_c_r_i_p_t_i_o_n

          |      'Rdcount' is part of the toy relational data base management
          |      system,  'rdb'.   It  lists the number of rows in a relation
          |      satisfying the optional select  expression.   If  no  select
          |      expression  is  given then it lists the total number of rows
          |      in the relation.  Standard input 1 must  be  directed  to  a
          |      file containing an 'rdb' relation.  The result is written to
          |      standard output.

          |      The input relation must be a file containing a relation that
          |      was  created  by 'rdmake' or other 'rdb' programs; the rela-
          |      tion cannot be read from the terminal.  The  select  expres-
          |      sion  is  formed  from  the logical operators "&" (and), "|"
          |      (or), and "~" (not) connecting relational conditions involv-
          |      ing two domains or a domain and a literal.


          | _E_x_a_m_p_l_e_s

          |      p.rel> rdcount
          |      p.rel> rdcount "color='red'"


          | _M_e_s_s_a_g_e_s

          |      "Sorry, a relation can't be read from the terminal"
          |      "relation is corrupted!!"
          |      "Cannot load input relation"
          |      "Invalid expression"
          |      "expected domain name or literal"


          | _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), rddiff (1), rddiv  (1),  rdint  (1),  rdmax  (1),
          |      rdmin (1), rdnat (1), rdsum (1)














            rdcount (1)                   - 1 -                   rdcount (1)