[Zope3-dev] Re: RDB support

[Matthew T. Kromer]

Stephan Richter wrote:

>
>> Insasmuch as I dont have the time to devote to this, I find that 
>> there are some restrictions in HOW SQL methods work, as opposed to 
>> their user-level syntax; in particular, the notion of collapsing all 
>> queries to a single string and then passing that string to a "query" 
>> method on the DA is something I'd like to deprecate in favor of:
>>
>> a query string constructor which takes a type and a value and returns 
>> a tuple of (string, value) which the string portion is to be embedded 
>> into the query string under construction, and the value is to be 
>> appended to an array of values to be passed to the extended query
>
>
> Can you elaborate on that? I am a little lost. Also, an example might 
> be nice. :-)
>

Well, what I'm after is something that will help construct query 
strings, e.g. to build the string

'select * from table where foo=:foo'

the bind string is DA specific -- for instance, DCOracle2 can bind by 
name or by position ':foo' vs ':1'.  Other DA's can use different 
methods.  So what you want is a mechanism to tell the DA "help me build 
the next binding parameter string for this value."

For things like positional binding, its pretty evident you'll need to 
keep some kind of state so you can increment the position.

You probably want some kind of querybuilder object which keeps track of 
its own state, and either knows about all kinds of DBAPI 2.0 parameter 
binding styles, or leverages a DA-specific binding routine.

-- 
Matt Kromer
Zope Corporation  http://www.zope.com/