rdsum (1) --- sum the values of an attribute 07/01/82 | _U_s_a_g_e | rdsum [] | _D_e_s_c_r_i_p_t_i_o_n | 'Rdsum' is part of the toy relational data base management | system, 'rdb'. It computes the sum of the values of a | specified attribute over all rows of the relation that | satisfy the optional select expression. If no select | expression is given then it computes the sum of the values | of an attribute over all rows of 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. The sum cannot | be computed for domains containing strings. | _E_x_a_m_p_l_e_s | p.rel> rdsum length | p.rel> rdsum "length>20" total_quantity | _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" | "Usage; rdsum [] " | "Domain not found" | "Strings can't be averaged" | "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), rdcount (1), rddiff (1), rddiv (1), rdint (1), | rdmax (1), rdmin (1), rdnat (1) rdsum (1) - 1 - rdsum (1)