Re: [binarycloud-dev] metabase & case function?

[John D. <jo...@we...>]

Just to be clear, metabase is a separate project that binarycloud is embedding.
From it's website (http://phpclasses.upperdesign.com/browse.html/package/20):

 Description:
 Package of classes that provide DBMS independent access and management of
 databases.

 Features:
 o Set of functions that call the selected DBMS driver objects functions
   supporting when possible: 
 * Database connection setup
 * Operation error handling
 * Query constant data conversion
 * Direct queries
 * Prepared queries
 * Query result rows random access
 * Retrieve a limit range of rows of a SELECT query.
 * Transactions
 * Database object creation (tables, indexes, sequences)
 * DBMS driver supported feature query
etc..

metabase is not what is responsible for actually generating your queries. The
only place (that I'm familiar with) where queries are generated at run-time are
in the EntityManager (and even then, only when we _can't_ use a compile-time
generated query), which hasn't actually made its way into binarycloud at this
point. But, generating queries requires a context. In the EntityManager, your
context is your entities. A predefined set of queries can be generated (mostly
at compile time, there's no reason to do them at run-time) for adding,
deleting, updating, and fetching, based on the fields which you have designated
as being the fields you want to be exposed to the world. 

You wouldn't in most cases, want to run mysql_fetch_field() at run-time and
just interate over everything you find, as that would run contradictory to
defining your entities at development time, and cause a lot of lost
functionality. 

That's not to say, however, that there shouldn't be something that you could
run on a particular table to generate an entity definition, which you can then
edit/fine-tune. On the other hand, maybe it would be more correct to generate
the SQL to make the tables based on the entity definitions, instead of the
other way around. That could allow for some pretty cool shit, such as automatic
schema migrations, true database independance, etc..

As to your question about the case control structure, see:
www.php.net/switch

John

On Thu, 5 Jul 2001, Alby Lash wrote:

> Whilst waiting for bc2 to be ready for production - I'm doing some
> restructuring of my current project and I'm trying to isolate all of my sql
> commands into a few dynamic functions. For the most part, I'll be doing a
> lot of updating, inserting, and querying - big surprise I know.
> 
> At any rate, I was thinking of building some tables that contain information
> about the _real_ db structure, so that when I do an insert on a variable
> driven table definition, I would be able to cycle through the field titles
> and build my sql call that way. However, I thought, why not just grab the
> table structure from the tables themselves using the mysql_fetch_field
> command. So, when I was thinking about this - bringing the db structure out
> in pieces to a simple dynamic sql query builder - I felt it sounded very
> much like what I thought the BC metabase to be. However, I did some poking
> around in the db "metabase" code and I couldn't find that much that made
> sense from that perspective.
> 
> Anyone want to try to explain to me what the metabase portion on BC is up
> to, and if there is anything like what I am describing in BC2? Also, I came
> across this often used function "case" that I couldn't find in the php
> manual. Anyone know what this does? It seems to have something to do with
> the data type thats in the table field.
> 
> Thanks,
> 
> Albert Lash
> al...@th...
> 
> 
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> 
> 

-- 

John Donagher
Application Engineer
Intacct Corp. - Powerful Accounting on the Web
408-395-0989
720 University Ave.
Los Gatos CA 95032
www.intacct.com

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