Re: [gnome-db] Studying the posibility to add parametrized statements

[Jeronimo Albi <amenofisvii yahoo com ar>]

On Mon, 27 Sep 2004 17:43:16 +0200
Vivien Malerba <vmalerba gmail com> wrote:

> 
> I've already done this for Mergeant/libmergeant.
> 
> Basically, any SQL statement can have parameters identified by a value
> of ## and parameter specifications between square brackets. For
> example one can write
> SELECT name FROM table WHERE name='joe' [...]
> or 
> SELECT name FROM table WHERE name=## [...]
> the above statement require one parameter for the "name=" condition.
> In the first statament, the default value for the parameter is 'joe'
> and in the second example, there is no default value for the
> parameter.
> 
> The para specifications between the square brackets are:
> :name="my para name"
> :descr="my para description"
> :type="the DBMS type"
> :nullok="TRUE"
> :isparam="FALSE" (default=TRUE)
> 
  Shouldn't type and nullok be initialized by each provider ? I only have
some experience using Firebird/Interbase, and they initialize each parameter
to ist correct type and null flag, after preparing the statement for execution.
  
  I'd really apreciate if someone can explain me how parameters are handled 
in Postgres and MySQL.

> so the above example can be:
> SELECT name FROM table WHERE name='joe' [:name="User name"
> :descr="Enter the user name to look for" :type="varchar"]
> 
  Its ok, but it seems to be impractical if you use too many parameters,
its kinda long, dont you think ?
  
> The SQL parser in libgda (libsql/*) already supports this syntax.
> 
> Libmergeant also has a small parser to isolate the parameters from any
> text (usefull when the SQL text can't be parsed by libgda's parser for
> various reasons); it's in libmergeant/parser/*
> 
  This would save lot of time, great !

> I think it would be a good idea to start libgda's implementation of
> parameters with the same syntax and the same libgda's parser.
> 
  Yes it might be a good idea, so if you and Rodrigo agree I'll use libmergeant
format.

  Originally I thought about using a parameter format like in PHP, that is, parameter
name between 2 "braces ?", like this:
	SELECT name FROM table WHERE name = {param_name}
but here we only use parameters name.

Regards.

-- 
Jeronimo Albi
Linux User #345522

Jabber ID: gtk_jeronimo jabber org
ICQ UIN:   136196282