I Agree Ivan. It seems the only reason ' * ' is seen as bad is that
people are referencing fields by column position, which IMO is about the
worst thing you can do!


Rob Martin
Software Engineer

phone +64 03 377 0495
fax +64 03 377 0496
web www.chreos.com

Wild Software Ltd



Ivan Prenosil wrote:

>"Ann W. Harrison" wrote:
>
>
>>Joe Martinez wrote:
>>
>>
>>
>>>>Select sales.*, customers.custfname, customers.custlname
>>>>from sales, customers
>>>>where ...
>>>>
>>>>
>>>wow. I really didn't know you could do it! Thanks for the syntax.
>>>
>>>
>>You can, but you really shouldn't. If some one adds a field to sales,
>>or drops one, or changed the field order in the table, your query is
>>going to mess up. One of the sadder parts of the history of relational
>>databases is that a loosey-goosey interactive query language was chosen
>>as the standard for program access. The "*" syntax should never be used
>>outside casual, hand-typed, one time queries.
>>
>>
>
>When application reads selected data, there is a secret (:-) structure
>called xsqlda, that among pointers to data itself contains description of types
>of data and fieldnames! It is used by most (all?) data access components
>(ibx, fib+, etc), so applications access fields by their names.
>If somebody specifies
>fields to be read from "select *" query by position number
>instead of field name, is it really good reason to blame
>the feature and not that developer ?
>
>
>
>>If some one adds a field to sales,
>>or drops one, or changed the field order in the table, your query is
>>going to mess up.
>>
>>
>
>If somebody drops the field, than it is dropped, and you do not retrieve
>its data regardless your using "select deletedfield, ..." or "select *" query.
>In fact, if the application use "select deletedfield, ..." than it is in troubles,
>while correctly written application using "select *" can in many cases
>continue to work (e.g. if the dropped field was just comment shown in grid).
>
>Here is another exampe how using "*" can avoid troubles with inconsitent
>database - I have several views that are used to restrict access
>to just subsets of rows, but that copy the structure of main table, i.e.
> Create View V1 as Select * From Tab Where condition1;
> Create View V2 as Select * From Tab Where condition2; etc
>When I add new field to the table, then I just recreate those views.
>Without "*" I would have to add that field to the table AND to ALL
>that views, so there would be much higher danger that I forget
>to change the definition somewhere.
>
>
>
>>The "*" syntax should never be used
>>outside casual, hand-typed, one time queries.
>>
>>
>
>I do not agree with this crusade :-) against "*".
>The fact that some feature can be misused is not enugh
>to say that it should "never be used ...", if that feature
>can be both safe and useful when used correctly.
>Otherwise, I would recommend to never use pointers
>(you can forget to initialize them, or free the memory, ...),
>never use national characters (text file usually do not contain
>information which charset is used, so there is always
>danger of misinterpretation), and several millions other things.
>
>Strangely, nobody mentioned "Insert Into Table Values (...)",
>i.e. without list of fieldnames, which, unlike "select *", do not pass
>names of fields in xsqlda (why?), so there I would fully agree with
>"should never be used outside casual, hand-typed, one time inserts".
>
>Ivan
>http://www.volny.cz/iprenosil/interbase/
>
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