[Vala] fix sqlite example

[Alexey Lubimov <avl l14 ru>]

Sqlite sample source from  http://live.gnome.org/Vala/SqliteSample  
contains some bugs.


Fixed example attached.





using GLib;
using Sqlite;


public class SqliteSample : GLib.Object {

    [NoArrayLength ()]
    public static int callback (void* data, int n_columns, string[] values, string[] column_names) {
        for (int i = 0; i < n_columns; i++) {
            stdout.printf ("%s = %s\n", column_names[i], values[i]);
        }
        stdout.printf ("\n");
        return 0;
    }

    public static int main (string[] args) {
        Database db;
        int rc;

        if (args.length != 3) {
            stderr.printf ("Usage: %s DATABASE SQL-STATEMENT\n", args[0]);
            return 1;
        }

        if (!FileUtils.test (args[1], FileTest.IS_REGULAR)) 
       {
            stderr.printf ("Database %s not exist or is directory\n",args[1]);
            return 1;
       }
             
          rc = Database.open(args[1], out db);

        
        if (rc != Sqlite.OK) {
            stderr.printf ("Can't open database: %d,%s\n", rc,db.errmsg());
            return 1;
        }


        rc = db.exec(args[2], (Sqlite.Callback) callback, null);

        if (rc != Sqlite.OK) { 
            stderr.printf ("SQL error: %d,%s\n", rc,db.errmsg());
            return 1;
        }

        return 0;
    }
}