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Antw: Re: XmlQuery and GOB

>>> Vivien Malerba <malerba gears linuxave net> 11.10.2000  13.39 Uhr >>>

> Wouldn't that be a bit complex for the user of the library (I mean having to record
> which id was affected to which element,...) Maybe we could create a document head
> (for any kind of query) which references database elements such as tables, views,
> sequences,... used in the query.

> These elements would have IDs assigned in any way (yours or mine),
> and then when in the query we need to talk about a table, we just need to have its
> id (and nothing more because the table information is already in the document head).

> The user would, to build a query:
> use the same functions you thought about, using only element names. The library
> would know if an element is already declared, and otherwise declare it. This
> processus is transparent to the user.
> 
> This also has the advantage that it is easy to scan that head to know which
> elements appear in the query.
> 
>
> Here is an example of document head:
> <head>
>   <table id="001" name="tab_a"/>
>   <table id="002" name="tab_b"/>
>   <sequence id="003" name="a_sequence"/>
> </head>
>
> What do you think?
>

To benefit of the XML id/idref mechanism, we need to use the id attribute to identify 
the table (or view, sequence, ...). To make things easy for the user this means, we should
use the name as the id. This in consequence makes the name attribute unnecessary.

But what do you think of the following change of the API:

example:
{
    XmlQueryItem *insert, *target, *dest;

    insert = xml_query_insert_new();
    target = xml_query_query_add_target_from_text(XML_QUERY_QUERY(insert),
                                         XML_QUERY_TYPE_TABLE,
                                         "tab_a");
    
    dest = xml_query_insert_add_dest_from_text(XML_QUERY_INSERT(insert), 
                                        target,                        
                                        "a");
    
    xml_query_query_add_const_from_text(XML_QUERY_QUERY(insert),
                                         dest,
                                         "1", 
                                         "int",
                                         FALSE);
    
    dest = xml_query_insert_add_dest_from_text(XML_QUERY_INSERT(insert), 
                                        target,
                                        "b");
    
    xml_query_query_add_const_from_text(XML_QUERY_QUERY(insert),
                                         dest, 
                                         "abc", 
                                         "char",
                                         FALSE);
}    

This also has the advantage to explcitely connect the values to the target variables,
which is not necessary for SQL but may be usefull for other situations.

When we render it into XML, we can use whatever id we want, because it's transparent 
to the user.

----------------
Gerhard
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