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From:Chris Frey Date:July 21 2005 10:15pm
Subject:Re: Newbie query use help.
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On Wed, Jul 20, 2005 at 04:10:46PM -0700, Benjamin Liu wrote:
> Hi folks,
> 
> I'm a humble non-programmer who just wants to read a float table value into
> a float variable.
> ----------------------------------------------------------------------------
> -------------
>  Query query = con.query();
>  query << "select kwh from basic120 order by time desc limit"; // Last value
> this column.
>  mysqlpp::ResUse res = query.use();
>  ???
>  float kwh = ???
> ----------------------------------------------------------------------------
> -------------
> I've tried using the method Fields but can't get it to compile.

Check out the usequery.cpp example, or some of the other files in the
examples/ subdirectory.

Here's a snippet:

                // Execute the query, but don't save results in memory
                mysqlpp::ResUse res = query.use();
                if (!res) {
                        std::cerr << "Result set is empty!" << std::endl;
                        return 1;
                }

                // Iterate through result set, printing each row.
                mysqlpp::Row r;
                while (r = res.fetch_row()) {
                        print_stock_row(r);
                }

i.e. you need to use a Row object, and fetch each row, then access the
data from that row.

More docs are here: http://tangentsoft.net/mysql++/doc/

- Chris

Thread
Newbie query use help.Benjamin Liu21 Jul
  • Re: Newbie query use help.Chris Frey22 Jul