dbReadTable-methods         package:RSQLite         R Documentation

_C_o_n_v_e_n_i_e_n_c_e _f_u_n_c_t_i_o_n_s _f_o_r _I_m_p_o_r_t_i_n_g/_E_x_p_o_r_t_i_n_g _D_B_M_S _t_a_b_l_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     These functions mimic their R/S-Plus counterpart  'get', 'assign',
     'exists',  'remove', and 'objects', except that they generate code
     that gets remotely executed in a database engine.

_V_a_l_u_e:

     A data.frame in the case of 'dbReadTable'; otherwise a logical 
     indicating whether the operation was successful.

_M_e_t_h_o_d_s:

     _c_o_n_n an 'SQLiteConnection' database connection object.

     _n_a_m_e a character string specifying a table name.

     _v_a_l_u_e a data.frame (or coercible to data.frame) object  or a file
          name (character).  In the first case, the data.frame is
          written to a temporary file and then imported to SQLite; when
          'value' is a character, it is interpreted as a file name and
          its contents imported to SQLite.

     _r_o_w._n_a_m_e_s in the case of 'dbReadTable', this argument can be a
          string or an index specifying the column in the DBMS table to
          be used as  'row.names' in the output data.frame (a 'NULL',
          '""', or 0  specifies that no column should be used as
          'row.names' in the output).

          In the case of 'dbWriteTable', this argument should be a
          logical specifying whether the 'row.names' should be output
          to the output DBMS table; if 'TRUE', an extra field whose
          name will be  whatever the R/S-Plus identifier '"row.names"'
          maps to the DBMS (see 'make.db.names').

     _o_v_e_r_w_r_i_t_e a logical specifying whether to overwrite an existing
          table or not.  Its default is 'FALSE'.  (See the BUGS section
          below).

     _a_p_p_e_n_d a logical specifying whether to append to an existing table
          in the DBMS.  Its default is 'FALSE'.

     ...  When 'dbWriteTable' is used to import data from a file,  you
          may specify  a field separator 'sep=' (defaults to '',''), 
          end-of-line delimiter 'eol' (defaults to ''\n''),  and a
          named list of field types (field types are inferred using
          'dbDataType').

_B_U_G_S:

     These RSQLite methods do not use transactions, thus it is
     dangerous  to specify 'overwrite=TRUE' in 'dbWriteTable' (the
     table is first removed and in case the data exporting fails the
     original table is lost forever).

_N_o_t_e:

     Note that the data.frame returned by 'dbReadTable' only has
     primitive data, e.g., it does not coerce character data to
     factors.

     SQLite table names are _not_ case sensitive, e.g., table names
     'ABC' and 'abc' are considered equal.

_R_e_f_e_r_e_n_c_e_s:

     See the Database Interface definition document 'DBI.pdf' in the
     base directory of this package or <URL:
     http://stat.bell-labs.com/RS-DBI>.

_S_e_e _A_l_s_o:

     'sqliteImportFile', 'SQLite', 'dbDriver', 'dbConnect',
     'dbSendQuery', 'dbGetQuery', 'fetch', 'dbCommit', 'dbGetInfo',
     'dbListTables', 'dbReadTable'.

_E_x_a_m_p_l_e_s:

     ## Not run: 
     conn <- dbConnect("SQLite", dbname = "sqlite.db")
     if(dbExistsTable(con, "fuel_frame")){
        dbRemoveTable(conn, "fuel_frame")
        dbWriteTable(conn, "fuel_frame", fuel.frame)
     }
     if(dbExistsTable(conn, "RESULTS")){
        dbWriteTable(conn, "RESULTS", results2000, append = T)
     else
        dbWriteTable(conn, "RESULTS", results2000)
     }
     ## End(Not run)

