Geografic-Information-System/db/db.columns/main.c

/****************************************************************************
 *
 * MODULE:       db.columns
 * AUTHOR(S):    Radim Blazek <radim.blazek gmail.com> (original contributor)
 *               Glynn Clements <glynn gclements.plus.com>, Markus Neteler <neteler itc.it>
 * PURPOSE:      list the column names for a table
 * COPYRIGHT:    (C) 2002-2006 by the GRASS Development Team
 *
 *               This program is free software under the GNU General Public
 *               License (>=v2). Read the file COPYING that comes with GRASS
 *               for details.
 *
 *****************************************************************************/

#include <stdlib.h>

#include <grass/gis.h>
#include <grass/dbmi.h>
#include <grass/glocale.h>


struct
{
    char *driver, *database, *table;
} parms;


/* function prototypes */
static void parse_command_line(int, char **);


int main(int argc, char **argv)
{
    dbDriver *driver;
    dbHandle handle;
    dbTable *table;
    dbString table_name;
    int col, ncols;

    parse_command_line(argc, argv);

    if (!db_table_exists(parms.driver, parms.database, parms.table)) {
	G_warning(_("Table <%s> not found in database <%s> using driver <%s>"),
		   parms.table, parms.database, parms.driver);
	exit(EXIT_FAILURE);
    }

    driver = db_start_driver(parms.driver);
    if (driver == NULL)
	G_fatal_error(_("Unable to start driver <%s>"), parms.driver);

    db_init_handle(&handle);
    db_set_handle(&handle, parms.database, NULL);
    if (db_open_database(driver, &handle) != DB_OK)
        G_fatal_error(_("Unable to open database <%s>"), parms.database);
    db_set_error_handler_driver(driver);

    db_init_string(&table_name);
    db_set_string(&table_name, parms.table);
    if (db_describe_table(driver, &table_name, &table) != DB_OK)
	G_fatal_error(_("Unable to describe table <%s>"), parms.table);

    db_close_database(driver);
    db_shutdown_driver(driver);

    ncols = db_get_table_number_of_columns(table);
    for (col = 0; col < ncols; col++)
	fprintf(stdout, "%s\n",
		db_get_column_name(db_get_table_column(table, col)));

    exit(EXIT_SUCCESS);
}


static void parse_command_line(int argc, char **argv)
{
    struct Option *driver, *database, *table;
    struct GModule *module;
    const char *drv, *db;

    /* Initialize the GIS calls */
    G_gisinit(argv[0]);

    table = G_define_standard_option(G_OPT_DB_TABLE);
    table->required = YES;

    driver = G_define_standard_option(G_OPT_DB_DRIVER);
    driver->options = db_list_drivers();
    if ((drv = db_get_default_driver_name()))
	driver->answer = (char *) drv;

    database = G_define_standard_option(G_OPT_DB_DATABASE);
    if ((db = db_get_default_database_name()))
	database->answer = (char *) db;

    /* Set description */
    module = G_define_module();
    G_add_keyword(_("database"));
    G_add_keyword(_("attribute table"));
    module->description = _("List all columns for a given table.");

    if (G_parser(argc, argv))
	exit(EXIT_FAILURE);

    parms.driver = driver->answer;
    parms.database = database->answer;
    parms.table = table->answer;
}