Hi Mark,
I've had a busy week. Sorry, I had drafted the beginnings of a reply about
result sets, but it looks like
a) events have over taken that discussion
b) it's a very small part of the overall project anyway.
It is quite incredible what you have achieved in so short a time and I look
forward to downloading it and playing with it.
Jon
On 8 June 2012 17:43, Mark Miesfeld <[email protected]> wrote:
> Result Sets:
> =========
>
> In the latest ooSQLite implementation I have implemented allowing the
> user to specify the format of a result set. Here are the details:
>
> There are 3 new constants that specify the format:
> OO_ARRAY_OF_DIRECTORIES, OO_ARRAY_OF_ARRAYS, and OO_STEM_OF_STEMS.
>
> By default the format is array of directories. The default can be
> changed either on a process-wide, database-wide, or prepared
> statement-wide basis. The default can also be over-ridden on a
> specific method invocation where the method returns a result set.
>
> Each of the 3 main classes has a recordFormat attribute. Setting the
> ooSQLite::recordFormat changes the default process wide. The
> ooSQLiteConnection::recordFormat attribute changes it for that
> database connection. And the ooSQLiteStmt::recordFormat changes it
> for that prepared statement.
>
> In writing the above, I noticed it is not a database-wide default, but
> rather a database connection-wide default. SQLite allows multiple
> concurrent connections to a database. Each ooSQLiteConnection object
> is a single connection to a database. You can have multiple
> ooSQLiteConnection objects all connected to the same database
> concurrently.
>
> SQLite handles the concurrent access to a database so in ooSQLite you
> can use multiple ooSQLiteConnection objects from different threads, or
> a single object from different threads.
>
> Note, in the 'classic Rexx' interface, the default format is a stem of
> stems. The default can be changed either by over-riding the default
> in a specific function call that returns a result set. Or, if the
> programmer is willing to use objects a little bit by using:
> .ooSQLite~recordFormat = .ooSQLite~OO_ARRAY_OF_XXX.
>
> In the testing subdirectory I've added 4 programs, execTest??.rex that
> demonstrate the above.
>
> One thing: the discussion on result sets kind of side-tracked me.
> SQLite doesn't really use the paradigm of result sets. Rather it uses
> a paradigm of stepping through a prepared statement, or it uses
> callback functions. There is only 1 API that can return a result set,
> exec(). This is a convenience API that is a wrapper for using a
> prepared statement.
>
> The exec() API is used through ooSQLiteConnection::exec(), or through
> the oosqlExec() function. SQLite doesn't support the idea of a
> cursor. You can't jump ahead to record 100, or go back to record 15.
> You have to step through each record, in order, one by one. In your
> Rexx program you can of course add your own support for a cursor by
> stepping through all the records and placing them in an array or other
> data structure. Once you have that, you can obviously go to any
> record you want.
>
> In the testing program are these 4 programs:
>
> execTestA.rex ==> result set is an array of arrays
> execTestD.rex ==> result set is an array of directories
> execTestS.rex ==> result set is a stem of stems
>
> and
>
> execNoExecTest.rex ==> implements the exact same task as the above 3
> programs, but steps through the prepared statement.
>
> The execNoExec.rex program is actually easier to write and looks
> cleaner, (IMO,) than the other 3.
>
> Class Names:
> ===========
>
> I made these changes to class names based on what was talked about so far:
>
> ooSQLiteDB ==> ooSQLiteConnection
> ooSQL ==> ooSQLiteConstants
>
> In addition, ooSQLiteConstants is a mixin class now and all the
> ooSQLite classes inherit it. While rewriting the current ooSQLite
> programs I have, I noticed that this seems very convenient and useful
> to me. You can have code like:
>
> do while stmt~step == stmt~ROW
>
> or
>
> -- Set the result set format to an array of arrays:
> .ooSQLite~recordFormat = .ooSQLite~OO_ARRAY_OF_ARRAYS
>
> Documentation
> ===========
>
> I have a oosqlite.pdf reference manual now. It lists every class,
> method of the class, constant, and function. Practically every one of
> these entries is simply a template entry at this point. I'm going to
> try and fill in the arguments and return parts of the template as soon
> as I can.
>
> The prebuilt package has oosqlite.pdf in the doc directory. In
> addition, there is a stand alone oosqlite-r7863.pdf file that can be
> downloaded from the SourceForge directory. My intent is to replace
> oosqlite-r7863.pdf periodically with oosqlite-rNNNN.pdf as I complete
> portions of the reference. (NNNN stands for the svn revision number
> so you can tell if you need the new version or not. The first page of
> the reference has the svn revision number on it.)
>
> Prebuilt Packages on SourceForge:
> ===========================
>
> It is also my intent to update the "preview" package on SourceForge
> fairly regularly as changes are made. The ReleaseNotes file is
> displayed on the SourceForge page. Towards the bottom of the Releases
> notes is a cumulative changes section. You can scroll down to see a
> synopsis of what has changed from one package to the next.
>
> --
> Mark Miesfeld
>
>
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