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From:Alex Date:August 21 2008 7:55am
Subject:Re: A way to copy mysqlpp::StoreQueryResult into a std::map?
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I think I should explain exactly what my application is supposed to do.

Basically, it has a CLI where the user could enter "help <command>". This
"help" command is then supposed to grab the name, syntax, and help text from
the command table which has already been loaded, and print it. However, it
will of course have to check if the help data for that specific command
actually *exists* so I was wanting to search through the vector (which I
apparently can with find()?) and see if the command is defined in the
command help table. If not, print nothing, if yes, print the data.

The table definition:

create table `command` (
`name` char(25) comment 'Name of the command.',
`help` longtext comment 'Help text for the command.',
`syntax` char(100) comment 'Syntax of the command.');
So, when querying the database for "SELECT * FROM `command`;" it would load
all the data up in a vector like this:

query_res[x][name]
query_res[x][help]
query_res[x][syntax]

So you can understand that I wouldn't be able to directly refer to the
specific command the user wants help for as the vector is split up in
numbers.

.. Hope I explained myself well enough. >_<

Thanks.
2008/8/21 Warren Young <mysqlpp@stripped>

> On Aug 20, 2008, at 7:11 AM, Alex wrote:
>
>  Can I ask why you wouldn't query the database  SELECT * FROM mytable
>> *WHERE
>> name='test'   *?
>>
>
>
> This can be a valid solution, too.  Whether it is the *best* solution
> depends on your application.
>
> If you already had a vector of records from a previous query and knew your
> target record was among them, you'd want to use the STL find() algorithm on
> it to pick it out instead of going back to the database server to pull it.
>
> If you didn't already have the record you want in memory, asking the
> database server to find it for you is superior, relative to pulling the
> contents of the table and searching it in memory.
>
> So much for simple cases.
>
> Sometimes you can't express your search criteria in SQL.  In that case, you
> need to do the search in C++.  Maybe you want to pull the entire table, or
> maybe you can express *part* of the criteria in SQL, and filter the subset
> down in C++.
>
> Maybe the table is small enough that it fits easily into RAM and your
> application is such that you don't need to worry about the table on disk
> changing out from under your program.  In that case, you might pull a copy
> of the table early in your program's execution time and run all of your
> queries against that using C++ code, because that will be far faster than
> going over an IPC channel to the database server and making it search files
> on disk each time.
>
> Software engineering is all about trading off development time, run time,
> complexity, maintainability, space, and correctness against each other.  You
> can't have everything, so you decide what you want most.  There is no single
> "right answer."  It always depends on the situation.  That's what makes this
> engineering, and not physics or mathematics.
>
>
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>


-- 
GamerzWoW - http://www.gamerzwow.net

Thread
A way to copy mysqlpp::StoreQueryResult into a std::map?Alex13 Aug
  • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young13 Aug
    • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex13 Aug
      • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young13 Aug
        • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex14 Aug
          • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex17 Aug
            • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young17 Aug
              • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex19 Aug
                • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young19 Aug
                  • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex20 Aug
                    • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young21 Aug
                      • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex21 Aug
                        • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young21 Aug
                          • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex21 Aug
                            • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex22 Aug
                              • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young22 Aug
                                • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex22 Aug
                                  • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young22 Aug
                                    • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex22 Aug
                                      • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex22 Aug
                                      • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young22 Aug
                                        • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex22 Aug
                                          • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young22 Aug
                                            • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex25 Aug
                                              • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Joel Fielder26 Aug
                                                • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex26 Aug
                                                  • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Joel Fielder26 Aug
                                                    • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex26 Aug
                                                  • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Warren Young26 Aug
                                                    • Re: A way to copy mysqlpp::StoreQueryResult into a std::map?Alex27 Aug